H202 Decomposition

Hydrogen Peroxide Decomposition Reaction Kinetics Purpose: In this trial, you will decide the rate law and initiation vitality for the iodide-catalyzed disintegration of hydrogen peroxide. Outline: The disintegration of hydrogen peroxide is catalyzed by iodide as per the accompanying response: 2H2O2 (aq) [pic] 2H2O (l) + O2 (g) The speed of the response is resolved from the reactants being devoured or from items that are being framed. This must be resolved tentatively by estimating the pace of progress in the convergence of one of the reactants or one of the products.The change of focus can be estimated by such physical properties, for example, the volume of a gas or shading power of an answer. The rate might be communicated, for instance, as moles per liter of item being shaped every moment, milliliters of gas being delivered every moment, or moles per liter of reactant being devoured every second. During this analysis, you will decide the pace of decay of hydrogen peroxide within t he sight of an impetus, iodide. The objective in this investigation is to conclude a rate law for the response, indicating the reliance of the rate on the convergences of H2O2 and I-.Your rate law will be of the structure: - [pic]= k[H2O2]x[I-]y k is the response rate consistent and relies just upon temperature. x is the response request as for the hydrogen peroxide fixation and y is the response request regarding the iodide particle focus. Your goal is to decide the numerical qualities for the examples x and y and rate steady, k. You will likewise contemplate the impact of temperature on the response. Materials: 0. 25M KI arrangement 3% H2O2 arrangement refined water 125mL or 250mL Erlenmeyer carafe 50mL gas assortment tube ring stand test tube cinch one-opening elastic plug eaker water shower 50mL alumni chamber 5 and 10 mL pipets thermometer Procedure: 1. Fill one measuring utencil about half full with water. Fill the gas assortment tube with water and upset into this container. Cinch the gas assortment cylinder to the ring stand. You will utilize this to gauge the volume of gas produced in the response. 2. Spot the Erlenmeyer carafe into a water shower. Fill the waterbath 66% loaded with water. Record the temperature of the water. Top the Erlenmeyer carafe with a one-opening elastic plug. Supplement a short bit of glass tubing into the one-opening elastic stopper.If vital, cut a bit of glass tubing and fire clean the finishes. Associate one finish of the elastic tubing to the glass tubing and supplement the opposite end into the gas assortment tube. You are currently prepared to begin the response. 3. Expel the elastic plug from the 50 mL carafe. Include 10 mL of the 0. 25 M KI arrangement and 15 mL of refined water to the jar. 4. Include 5 mL of 3% H2O2 to the Erlenmeyer cup. Whirl to blend the arrangements and promptly supplant the elastic plug. Start taking oxygen volume readings right away. 5. Record the time and oxygen volume (mL) like clockwork for 2 40 econds or 30mL (whichever starts things out). Twirl the flagon during the response to forestall the arrangement getting overly soaked with oxygen. 6. Rehash the investigation, utilizing a spotless carafe, with10mL of the 0. 25-M KI arrangement and 10mL of refined water, at that point including 10 mL of the 3% H2O2. 7. Rehash the trial, this time utilizing 20mL of the 0. 25-M KI arrangement and 5mL of refined water, at that point including 5 mL of the 3% H2O2. 8. Supplant the water in the water shower containing the Erlenmeyer cup, with water that is 10-20(C hotter than already used.Repeat the analysis utilizing 10mL of 0. 25M KI, 15mL of refined water and 5mL of the 3% H2O2. 9. For every one of the three preliminaries, plot the volume of oxygen in milliliters versus the time right away. Fit the information with the best-fit bend or straight line for every preliminary, overlooking the initial sixty seconds of information. (Try not to draw a line that interfaces point to point. ) 1 0. Compute the slant (mL/sec) of each line. The slant of each line gives the pace of oxygen creation in mL/seconds. 11. Utilize the inclines and the subtleties from every preliminary to decide the response orders for the I-and H2O2.Note that the KI and H2O2 volume are corresponding to their focuses in the response arrangement. | |Slope (mL/sec) |KI |H2O2 | |Trial 1 | |10mL |5mL | |Trial 2 | |10mL | |Trial 3 | |20mL |5mL | 2. Ascertain the rate consistent, k, for the condition: - [pic]= k[H2O2]x[I-]y Substitute qualities for [H2O2], [I-], x,y and - [pic]/[pic]into the condition and understand for k. Utilize the response orders decided above for x and y. Utilizing information from one of the preliminaries, ascertain the molarity of the H2O2 and I-in the response arrangement and the hydrogen peroxide vanishing rate. Utilize these qualities to substitute into the above condition. You can decide the hydrogen peroxide vanishing rate from the pace of oxygen production.Convert the pace of o xygen creation to moles every second utilizing PV=nRT. Make sure to diminish the weight of the oxygen by the water fume pressure. Use stoichiometry to change over moles of oxygen to moles of hydrogen peroxide. Utilize the arrangement volume to change over the moles every second to molarity every second. Figure the rate steady, k, to two huge digits. Make certain to incorporate units. 13. Analyze your outcomes to decide the impact that temperature had on the response rate. 14.Calculate k for the higher temperature, and, utilizing both k esteems decide the actuation vitality for this reaction[1]. Questions: 1. How might your determined response rate constants and determined enactment vitality have been influenced if the ostensibly 3% hydrogen peroxide had a convergence of just 2%? 2. How might your outcomes have been influenced if additional water had incidentally been added to the response blend? 3. In the event that you don't disturb the response arrangement, it can get supersaturat ed with oxygen. How might this influence your outcomes? . On the off chance that you had the option to straightforwardly decide the centralization of hydrogen peroxide in the response arrangement, you would have had the option to diagram the fixation versus time. What might that chart resemble? 5. In the event that you had the option to legitimately decide the grouping of iodide in the response arrangement you would have had the option to diagram its fixation versus time. What might that chart resemble? 6. What might you diagram versus time to decide the response rate steady? How might you ascertain k from the chart? dapted from a lab at Occidental College http://divisions. oxy. edu/tops/Kinetics/energy. pdf â€â€â€â€â€â€â€â€ [1] Activation vitality, Ea, is identified with the response rate steady, k, by the Arrhenius condition: k=Ae-Ea/RT. R is the perfect gas steady, 8. 314510 J/(K†¢mol). An is the recurrence factor with units of L/mol†¢s, and is i dentified with the portion of crashes that have the right geometry. The actuation vitality can be resolved utilizing response rate constants from two distinct temperatures utilizing the Arrhenius Equation reworked as: ln k2 †ln k1 = †[pic]

Employee Motivation and Incentives Coursework Example | Topics and Well Written Essays - 1000 words

Representative Motivation and Incentives - Coursework Example Duty involves doing one’s individual obligation all the while with different specialists so every unit or division supplements each other in the whole work process; making a smooth progression of facilitated steps that will prompt the achievement of a specific objective (Dess et al, 2010: 24-25). Acknowledging objectives in like manner needs great representative execution. It is noteworthy that the objectives imagined are sufficiently rousing to spur laborers to carry out their responsibility well and to give their best grinding away. Thusly, all objectives or goals must be reasonable and reachable inside a given time period so that even the basic agent comprehends the exertion in question (Dess et al, 2010: 24). 2. Are on the whole local states of mind equivalent? If not, clarify why. Not every single local mind-set are equivalent in light of the fact that an individual has an alternate discernment and response to specific issues and circumstances all through the workplace. A n association has frequently been seen between an employee’s state of mind and the various angles that the individual in question needs to manage in the work environment. This incorporates making an agreeable showing yield, being inventive and persuaded; and reacting emphatically to the assignment forced of being a cooperative person (MT, 2008: n.p.). While singular temperaments of representatives change, it is basic to consider that the aggregate state of mind or the disposition of most of the laborers at a given time and spot will have an increasingly huge effect for producing accomplishment for the organization or association. Moderately, states of mind are infectious particularly in the event that it originates from the big shots of the administration, similar to the administrators and directors who can either make the employees’ working condition a pleasant or a hopeless one since it influences the whole team’s soul; along these lines deciding the general d isposition representatives display inside the working environment (MT, 2008: n.p.). Giving representatives positive criticism sometimes decreases the contact of passing on terrible temperaments consequently upgrading work quality and reducing frailties. 3. Talk about the significance of support and its impact in expanding work viability. Ongoing financial changes have opened the eyes of most entrepreneurs about how an organization or association must be overseen. This incorporates the way that the typical workers should in like manner be allowed the chance to take an interest in the board choices about the prosperity of the whole association. In generally huge and medium associations or partnerships, the aggregate voice of the laborers is regularly heard through the association. While littler organization representatives will in general haggle legitimately with their separate organization proprietors in regards to advantages and working hours. The quintessence of laborers or worker support typically relies upon the financial and social advantages they will get. A few firms offer their laborers a stake in the organization, which in a monetary outlook urges laborers to work better since they include some money related venture inside the substance. Then again, associations that take into account the social needs of their workers by giving them better employer stability or residency similarly give fulfillment in realizing that they despite everything have an occupation tomorrow with a consistent salary to pay for their costs. Thus representatives are moved to accomplish their function admirably so the organization or association can accomplish its target in having better money related solidness (Summers et al, 2005.: p. 2). 4. Distinguish an association and study the discipline rehearses

Essay Examples For Job Applications

Essay Examples For Job ApplicationsWhen it comes to essay samples for job applications, there are many different ways that you can take to get the information that you need. You can take this information and use it in your resume. Or, you can go into the hiring process knowing that you are going to have an advantage.There are a lot of job application essays that you can write yourself or find on websites that do this for you. However, they may not be exactly what you want. They may be too generic, or they may not even make sense. To get your job application essays to be the best that they can be, you will need to learn how to find the sample essays that are going to give you the edge you need.You should always read the resume of the person that you are applying to. You should be able to see whether or not they were able to use a typical resume. If so, then you know that they were able to write an essay with just the resume.Many people use other forms of writing when they are trying t o get a job that they like, but there are some different things that they can do. They can begin with a resume that is similar to theirs, or they can write a unique one that will be unique to them. The end result is that they will stand out from other resumes and they will be much more likely to get the job that they want.Another place that you can find essay samples for job applications is on-line. In this case, you will be able to find several different kinds of materials that you can use. The advantage to these types of essays is that they have been thought out and can easily be written from scratch.There are also many different kinds of techniques that people use to write the resume. They might have used a different kind of software and they will not have a way to go back and add content to it. This is why you can find such a wide variety of essay samples for job applications on the Internet.A good essay for any situation has to be one that tells a story. The person who is writi ng it is having to tell their story from beginning to end, so that they can convey something about themselves and their past. A good essay is one that will have a strong storyline and good facts to support it.Keep this in mind when you are thinking about writing good quality work for the essay samples for job applications. Make sure that you start out with a good story that will stick with the reader, so that they can see your point of view, and will be interested in what you have to say in the future.

Lears Relinquishment of Power in Shakespeares King Lear

Lears Relinquishment of Power in Shakespeares King Lear King Lear is an actor who can only play the king. Thus, after he has abdicated his throne, passing the authority to his posterity, he still demands respect and power, which he is unable to claim from any of his former subjects, even his daughters. And as a king with no kingdom, he is an actor with no role to play, the most loathsome of all conditions. Lear himself realizes this, and in scene 4, he cries: Why, this is not Lear (4.204). And later in the same speech, he says: Who is it that can tell me who I am? (4.209). Lear is stuck in his role as king, unable to act in any other manner and powerless to provide for himself, causing the ultimate downfall of he and his†¦show more content†¦(1.124-8) Lear cannot deny his ultimate role as the king. He desires to maintain his name and his rights as king, but to give control of the kingdom to his daughters and their husbands. However, this cannot work: We know immediately that he is doomed to painful disillusionment by his assumption that his identity as king, father, and man, being fixed in the macrocosmic scheme of things, must remain unshaken without its worldly supports (Egan 32). So, King Lears exercising of this nonexistent power establishes his tragic flaw and the problem of the play: the power of the kingdom must reside in Lear only. The consequences of this problem appear very early in King Lear. Near the end of the initial scene, Cordelia has already deciphered the evil designs of her sisters. As she is leaving them to live with her new husband, Cordelia says: Use well our father. / To your professed bosoms I commit him (1.258-9). She realizes that her sisters are using their pseudo love for their father to garner the power of the throne and to misuse the authority that Lear has given them. Cordelia also points out in this statement that she realizes that her father is stuck in his role as king, unable to provide for himself, thus needing the support of the evil sisters to care for him. And they have little use for him: Nothing will come of nothing, and since he hasShow MoreRelated Essay on Facing the Consequences in King Lear999 Words   |  4 PagesKing Lear:   Facing the Consequences      Ã‚  Ã‚  Ã‚   Shakespeares tragedy King Lear is a detailed description of the consequences of one mans decisions.   This fictitious man is Lear, King of England, whose decisions greatly alter his life and the lives of those around him.   As Lear bears the status of King, he is, as one expects, a man of great power.   But, sinfully, he surrenders all of this power to two of his daughters, as a reward for their demonstration of love towards him.   This untimely

Essay about Alternatives to Human-embryo Stem-cell Research

Alternatives to Human-embryo Stem-cell Research This essay counters the media and many scientists claims that there are no viable alternatives to human-embryo stem-cell research (ESCR). The media restate the claim (made repeatedly in NIH documents) that adult stem cells do not have the same potential as embryonic stem cells, which in theory can form any tissue. But studies done with adult stem cells (studies which mirror the ones done with embryonic stem cells) show that adult stem cells do have the capacity to form essentially any tissue. The most misleading term which continues to be used is pluripotent. Literally, this means able to form most (but not all) tissues. This term continues to be used†¦show more content†¦The best sources are from our own organs termed adult stem cells or tissue stem cells. Another excellent source is cord blood; the small amount of blood left in an umbilical cord after it is detached from a newborn is rich in stem cells. In the last two years, weve gone from thinking that we had very few stem cells in our bodies, to recognizing that many (perhaps most) organs maintain a reservoir of these cells. Weve known for some time that bone-marrow stem cells can make more blood, but now we know that these adult stem cells can also make bone, muscle, cartilage, heart tissue, liver, and even brain. Interestingly enough, we now know that our brain contains stem cells which can be stimulated to make more neurons, or to take up different job descriptions as muscle or blood. Bone marrow and cord blood are already successfully being used clinically, while clinical use of embryonic stem cells is years away. Current clinical applications of adult stem cells include treatments for cancer, arthritis, lupus, and making new corneas, to name a few. One distinct advantage of using our own adult stem cells is that there will be no transplant rejection, since it is our own tissue. Use of human embryonic stem cells will require lifelong use of drugs to prevent rejection of the tissue. Or, the patient will have to beShow MoreRelatedThe Debate Over Stem Cell Research1685 Words   |  7 PagesWhile the use of stem cells can offer a lot to the scientific community, the derivation of stem cells from embryos is ethically unacceptable; and the use of stem cells in humans should be completely prohibited. Since the first research on embryo stem cells in 1998 on mice the controversy has been relentless (Timeline), and even now, scientists have made great strides in waning off of embryonic stem cells and instead using induced pluripotent stem cells from adults, however these have their issuesRead MoreEmbryonic Stem Cell Research Essay710 Words   |  3 PagesResearch on stem embryonic stem cells We live in a world where genetic sciences have gone beyond laws, and past the imagination. We have come to a point where we don’t know anymore what is right, and what is wrong. 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Though this new science may be very beneficial, not everyone can agree on the ethics ofRead MoreThe Heated Debate Concerning Stem Cell Research Essay1043 Words   |  5 PagesStates, research has become a viable tool for sustaining and prolonging human life. As rese arch evolves, it brings along with it much controversy, especially where stem cell research is involved. Stem cell research can bring new insight to today’s medical field. This may be the way of finding solutions concerning many health injuries and diseases which would diversely be thought of as implausible. Thoughts can be influenced by Deborah White, in Pros Cons of Embryonic Stem Cell Research, â€Å"Embryonic

The Hunters Moonsong Chapter Twenty-Six Free Essays

â€Å"Are you sure you don’t want us to cal your parents, miss?† The campus security officer’s voice was gruff but kind, and his eyes were worried. For a second, Meredith let herself picture having the kind of parents he must be imagining: ones who would swoop in to rescue their daughter, wrap her up and take her home until the horrible images of her friend’s death faded. Her parents would just tel her to get on with the job. We will write a custom essay sample on The Hunters: Moonsong Chapter Twenty-Six or any similar topic only for you Order Now Tel her that any other reaction was a failure. If she let herself be weak, more people would die. More so because Samantha had been a hunter, from a family of hunters, like Meredith. Meredith knew exactly what her father would have said if she had cal ed him. â€Å"Let this be a lesson to you. You are never safe.† â€Å"I’l be okay,† she told the security guard. â€Å"My roommates are upstairs.† He let her go, watching her climb the stairs with a distressed expression. â€Å"Don’t worry, miss,† he cal ed. â€Å"The police wil get this guy.† Meredith bit back her first reply, which was that he seemed to be putting a lot of faith in a police force that had yet to find any clues as to the whereabouts of the missing people or to solve Christopher’s murder. He was only trying to comfort her. She nodded to him and gave a little wave. She hadn’t been any more successful than the police, not even with Samantha’s help. She hadn’t been trying hard enough, had been too distracted by the new place, the new people. Why now? Meredith wondered suddenly. It hadn’t occurred to her before, but this was the first death, attack, or disappearance that took place in a dorm room instead of out on the quad or paths of the campus. Whatever this was, it came after Samantha specifical y. Meredith remembered the dark figure she chased away after it attacked a girl, a girl who said she didn’t remember anything. Meredith recal ed the flash of pale hair as the figure turned away. Did Samantha die because they got too close to the kil er? Her parents were right. No one was ever safe. She needed to work harder, needed to get on with the job and fol ow up on every lead. Upstairs, Bonnie’s bed was empty. Elena looked up from where she was lying, curled up on her bed. Part of Meredith noted that Elena’s face was wet with tears and knew that usual y she would have dropped everything to comfort her friend, but now she had to focus on finding Samantha’s kil er. Meredith crossed to her own closet, opened it, and pul ed out a heavy black satchel and the case for her hunter’s stave. â€Å"Where’s Bonnie?† she asked, tossing the satchel onto her bed and unbuckling it. â€Å"She left before I got up,† Elena answered, her voice shaky. â€Å"I think she had a study group this morning. Meredith, what’s going on?† Meredith flipped the satchel open and began to pul out her knives and throwing stars. â€Å"What’s going on?† Elena asked again, more insistently, her eyes wide. â€Å"Samantha’s dead,† Meredith said, testing the edge of a knife against her thumb. â€Å"She was murdered in her bed by whatever’s been stalking this campus, and we need to stop it.† The knife could be sharper – Meredith had been letting her weapons maintenance slide – and she dug in the bag for a whetstone. â€Å"What?† Elena said. â€Å"Oh, no, oh, Meredith, I’m so sorry.† Tears began to run down her face again, and Meredith looked over at her, holding out the bag with the stave in it. â€Å"There’s a smal black box in my desk with little bottles of different poison extracts inside it,† she said. â€Å"Wolfsbane, vervain, snake venoms. We don’t know what we’re dealing with exactly, so you’d better fil the hypodermics with a variety of things. Be careful,† she added. Elena’s mouth dropped open, and then, after a few seconds, she closed it firmly and nodded, wiping her cheeks with the backs of her hands. Meredith knew that her message – mourn later, act now – had been received and that Elena, as always, would work with her. Elena put the stave on her bed and found the box of poisons in Meredith’s desk. Meredith watched as Elena figured out how to fil the tiny hypodermics inset in the ironwood of the stave, her steady fingers pul ing them out and working them cautiously open. Once she was sure Elena knew what she was doing, Meredith went back to sharpening her knife. â€Å"They must have come after Samantha on purpose. She wasn’t a chance victim,† Meredith said, her eyes on the knife as she drew it rhythmical y against the whetstone. â€Å"I think we need to assume that whoever this is knows we’re hunting him, and that therefore we’re in danger.† She shuddered, remembering her friend’s body. â€Å"Samantha’s death was brutal.† â€Å"A car tried to run me and Damon down last night,† Elena said. â€Å"We had been trying to investigate something weird in the library, but I don’t know if that’s why. I couldn’t get a look at the driver.† Meredith paused in her knife sharpening. â€Å"I told you that Samantha and I chased away someone attacking a girl on campus,† she said thoughtful y, â€Å"but I didn’t tel you one thing, because I wasn’t sure. I’m stil not sure.† She told Elena about her impressions of the black-clad figure, including the momentary impression of paleness below the hoodie, of almost white hair. Elena frowned, her fingers faltering on the staff. â€Å"Zander?† she asked. They both looked at Bonnie’s unmade bed. â€Å"She real y likes him,† Meredith said slowly. â€Å"Wouldn’t she know if there was something wrong with him? You know†¦Ã¢â‚¬  She made a vague gesture around her head, trying to indicate Bonnie’s history of visions. â€Å"We can’t count on that,† Elena said, frowning. â€Å"And she doesn’t remember the things she sees. I don’t think he’s right for Bonnie,† she continued. â€Å"He’s so – I mean, he’s good-looking, and friendly, but he seems off somehow, doesn’t he? And his friends are jerks. I know it’s a long way from having terrible friends to being dangerous enough to do something like this, but I don’t trust him.† â€Å"Can you ask Stefan to watch him?† Meredith asked. â€Å"I know you’re taking a break from dating, but this is important, and a vampire would be the best one to keep an eye on him.† Stefan looked so sad the other night, she thought distantly. Why shouldn’t Elena cal him? Life was short. She felt the blade of the knife against her thumb again. Better. Putting the sharpened knife down, she reached for another. Elena wasn’t answering, and Meredith looked up to see her staring hard at the stave, her mouth trembling. â€Å"I – Stefan isn’t talking to me,† she said in a little burst. â€Å"I don’t think – I don’t know if he’d help us.† She closed her mouth firmly, clearly not wanting to talk about it. â€Å"Oh,† Meredith said. It was hard to imagine Stefan not doing what Elena wanted, but it was also clear that Elena didn’t want to ask him. â€Å"Should I cal Damon?† she suggested reluctantly. The older vampire was a pain, and she didn’t real y trust him, but he was certainly good at being sneaky. Elena sucked in a breath and then nodded briskly, her mouth set. â€Å"No, I’l cal him,† she said. â€Å"I’l ask Damon to investigate Zander.† Meredith sighed and leaned back against the wal , letting the knife drop onto her bed. Suddenly, she was terribly tired. Waiting for Samantha in the gym that morning seemed like a mil ion years ago, but it stil wasn’t even lunchtime. She and Elena both looked at Bonnie’s bed again. â€Å"We have to talk to her about Zander, don’t we?† Elena asked quietly. â€Å"We have to ask her whether he was with her al last night. And we have to warn her.† Meredith nodded and closed her eyes, letting her head rest against the coolness of the wal , then opened them again. Tired as she was, she knew the images of Samantha’s death would come back to her if she let herself pause for even a moment. She didn’t have time to rest, not while the kil er was out there. â€Å"She’s not going to be happy about it.† How to cite The Hunters: Moonsong Chapter Twenty-Six, Essay examples

The Effect of Temperature and Concentration on the Rate of the Briggs-Rauscher Reaction free essay sample

Like any experiment, there were a number of potential errors during the procedure of the experiment. Errors could have arisen as a result of the uncertainties associated with the instruments I used to take measurements, and also as a result of errors associated with the actual method. Of course, due to the limitations of the procedure, they could not be eliminated completely, so I will explain what I did to reduce them to an acceptable level and how I could have improved my method to reduce them even further. Equipment justification The following table shows the reasons for my choice of equipment in carrying out my method. Equipment| Justification| 100 cm3 burette| I needed to accurately measure out large quantities of hydrogen peroxide (90 cm3 and 150 cm3). The 100 cm3 burette is a precise instrument and would allow me to measure out the hydrogen peroxide by filling it fewer times than I would need to with 50 cm3 burette. We will write a custom essay sample on The Effect of Temperature and Concentration on the Rate of the Briggs-Rauscher Reaction or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page | 50 cm3 burette| I needed to repeatedly measure out small volumes of solutions A–I. The burette made the task convenient, and it is a precise instrument. 250 cm3 volumetric flask| I needed to make up a specific volume of a standard solution. The volumetric flask has a low error. | 100 cm3 volumetric flask| I needed to make up a specific volume of a standard solution. The volumetric flask has a low error. | Top pan balance| I needed to accurately weigh out small amounts of solid when making up my solutions. | 25 cm3 Mohr pipette| I used the pipette to accurately transfer sulfuric acid when making up solutions. I could not do this with a volumetric pipette, as the volume I transferred was 20 cm3. Distilled water| I used the distilled water to wash out any glassware and storage jars before using them to avoid contamination. | Crushed ice| I used the ice to cool my reactants down to 10  °C. | Water bath| I used the water bath to heat my reactants up to 30  °C, 40  °C and 5 0  °C. It kept the temperature constant—it does not cool down like hot water in a beaker. | Thermometer| I needed to measure the temperature of the reactants before pouring them into the beaker and stirring them. | Magnetic stirrer| I used the stirrer to ensure the reaction mixture was uniformly mixed. This was necessary to produce sharp colour changes. | Stopwatch| I used the stopwatch to record the times of the colour changes. These are the values I needed to investigate the effect of temperature and concentration on rate. | Measurement errors These are the errors associated with the equipment I used when weighing out solids, measuring volumes of liquid, recording the temperature of my reactants, and recording the times of the colour changes. Equipment| Error| 100 cm3 burette|  ±0. 2 cm3| 50 cm3 burette|  ±0. 1 cm3| 250 cm3 volumetric flask|  ±0. 3 cm3| 00 cm3 volumetric flask|  ±0. 2 cm3| 25 cm3 Mohr pipette|  ±0. 1 cm3| Top pan balance|  ±0. 005 g| Thermometer|  ±0. 5  °C| Stopwatch|  ±0. 005 s (for instrument),  ±0. 5 s (for measurements),  ±0. 05 s (for measurements at 50  °C)| The stopwatch could record to 2 d. p. but the times I recorded were affected by my reaction time. Recording to 2 d. p. would be pointless, as I could not record that precisely. I decided to record the times to the nearest second, except for my results at 50  °C, where I recorded them to 1 d. p. because of the short duration of time between the colour changes. Percentage uncertainties Using the measurement errors, I can work out the percentage uncertainties for my measurements. I can do this using the formula: percentage uncertainty = error / value of measurement x 100% I made multiple measurements with many of the instruments I used. For these measurements, I will find the uncertainties for three of the values (the highest, the lowest and one close to the average) to give an indication of how the uncertainty changed across the range of measurements I made. Equipment| Error| Measurement| Percentage uncertainty / %| 100 cm3 burette|  ±0. cm3| 150 cm3| (I used the burette twice, so 0. 4 / 150 =) 0. 27| | | 90 cm3| 0. 22| 50 cm3 burette|  ±0. 1 cm3| 10. 00 cm3| 1. 0| | | 5. 00 cm3| 2. 0| | | 1. 00 cm3| 10| 250 cm3 volumetric flask|  ±0. 3 cm3| 250 cm3| 0. 12| 100 cm3 volumetric flask|  ±0. 2 cm3| 100 cm3| 0. 20| 25 cm3 Mohr pipette|  ±0. 1 cm3| 20 cm3| 0. 50| Top pan balance|  ±0. 005 g| 26. 75 g| 0. 02| | | 10. 7 g| 0. 05| | | 0. 85 g| 0. 59| Thermometer|  ±0. 5  °C| 50  °C| 1. 0| | | 30  °C| 1. 7| | | 10  °C| 5. 0| Stopwatch|  ±0. 5 s| 437 s| 0. 11| | | 95 s| 0. 53| | | 1 s| 50| |  ±0. 05 s (at 50  °C)| 31. 8 s| 0. 57| | | 12. 9 s| 0. 388| | | 1. 5 s| 3. 3| The percentage uncertainties varied wildly depending on the error of the instrument and the value of the measurement. The largest uncertainty (50%) came from the stopwatch when I used it to record a time of 1 s. However, this would not have affected my calculations to a great extent, as I only used the time to calculate the blue cycle for the first oscillation. It would not have affected the value I calculated for the average oscillation period by a significant amount, and would not have noticeably affected the trends in my graphs. This applies to all uncertainties from the stopwatch. I could have recorded all my times to 1 d. p. to improve the accuracy of my calculations and draw graphs that showed a trend closer to the true one. The second most significant uncertainty (10%) was for the burette when I used it to add 1 cm3 of solution to different test tubes in order to test the effect of changing the concentration of propanedioic acid, manganese(II) sulfate(VI) and sulfuric acid. This is a very significant error that could have definitely weakened the accuracy of my results. It might explain, for instance, the wildly varying number of oscillations I observed for tests at 0. 01 M manganese(II) sulfate(VI), as well as the increased appearance of anomalous results at lower concentrations. Even the uncertainty for a measurement of 10 cm3 using the burette was 1%, which is significant. In order to reduce the instrumental error, I could have used a 1 cm3 pipette or syringe to measure very small volumes of solution. I could not have done much more to conveniently transfer larger volumes of solution (i. e. p to 10 cm3) while reducing the error, as even a 10 cm3 pipette has the same error as a 50 cm3 burette, and it would have been extremely time-consuming to transfer my solutions to test tubes using a 1 cm3 pipette. Still, a 1% uncertainty would not have dramatically affected my results. Another source of significant percentage uncertainties was the thermometer—at every temperature the uncertainty was above 1%. At 10  °C, it was 5%, which is particularl y significant. This means that I could have started stirring the reactants at a temperature between 9. 5  °C and 10. 5  °C. However, there were no thermometers more precise than  ±0. 5  °C, so there is not much I could have done to reduce this error. Anyway, looking back at my raw results, the times I recorded for tests at 10  °C were not particularly discordant in comparison with the results I obtained for the other temperatures. All other errors were below 1%, so were insignificant. I used the volumetric flasks correctly, using a Pasteur pipette to add the distilled water for the last centimetre below the graduation mark, checking the mark at eye level in order to make sure I stopped at the correct point. I took readings from the bottom of the meniscus at eye level when using the Mohr pipette and burettes to reduce parallax error. I had to round up the mass of manganese(II) sulfate(VI)-1-water I weighed on the top pan balance from 0. 845 g to 0. 85, so an 4 d. p. analytical balance would have been better for this, but I did not have access to one. Procedural errors These are the errors that could have arisen from the method and improper technique. When making up solutions, it is important to rinse out the glassware and other equipment with distilled water before use. This was particularly vital for the BR reaction, due to its high sensitivity to chloride ions. As mentioned in my method, I did wash out all equipment with some distilled water before putting them in contact with any reactants to minimise the risk of contamination. It would have been impossible to prevent a small amount of solution from being lost when transferring them. When transferring from a beaker through a funnel to volumetric flask, the small amount left would have led to a lower final concentration then planned. I minimised this error by washing out the beaker with distilled water three times. When pouring solution from the test tubes into the reaction beaker, a small amount is also lost. However, the amount left would have little effect on the results because it is a systematic error, i. e. it is repeated every time the solution is poured. I always inverted the volumetric flasks when making up solutions in order to ensure homogeneity. Before pouring them into the burettes, I gave the storage bottles a swirl in case the uniformity of the solution had been affected during storage. This would prevent the trials from being tested at different concentrations, which would have compromised the accuracy of my results. In addition, I used a magnetic stirrer to make sure the consistency of the solution remained even within the reaction beaker. This also meant that the colour changes were sharper. It was especially important that the blue colour change was sharp, as this is the value I used to calculate the oscillation period, and therefore, rate of reaction. However, because human reaction time is not perfect, there was always some delay between the colour change and the pressing of the stopwatch. This is why I could not record times accurate to 2 d. p. At higher temperatures, i. e. 40  °C and 50  °C, the water from the solutions in the test tubes evaporated a lot faster than at room temperature while being heated in water bath, which would have increased the concentrations of the reactants and overstated the effect of the temperature increase. I minimised this error by removing the test tubes from the water bath as soon as possible after the temperature of the reactants reached the appropriate level. Next time, I would seal the test tubes using stoppers to prevent any water vapour from escaping. Unfortunately, the reactants could not remain at their starting temperature while being stirred, as they had to be poured into a beaker and set on a magnetic stirrer. This means that during tests at 30  °C, 40  °C and 50  °C, the reactants cooled down; at 10  °C, the reactants warmed up. This would have understated the effect of temperature on rate. There was a problem with the hydrogen peroxide in the burette. Because it was stored in the fridge, it was cold when I took it out. As it warmed up, there were noticeable increases in the level of solution in the burette. Trials that were run near the start of the session may have used colder, more concentrated hydrogen peroxide, which would have affected the rate of reaction. I only took the temperature of reactants when I tested the effect of temperature. In order to resolve this problem next time, I would take out the hydrogen peroxide at the very start of the lesson and wait for it to warm up while setting up the other burettes, magnetic stirrer etc. and also take the temperature of the reactants when testing concentration to see if it might have had a secondary effect on the rate. The potassium iodate(V) was not soluble enough to make Solution F (potassium iodate(V), 0. 5 M). Although I did manage to fully dissolve it with the aid of heat, a small amount crystallised out of solution after it cooled down, which would have decreased the solution’s concentration and affected the results I obtained for the tests where I changed the concentration of potassium iodate(V) and sulfuric acid. Next time, I would change the experiment and run the tests at lower concentrations. Reliability My results were quite reliable, as I ran the reaction three times at each temperature and concentration. The number of oscillations was usually the same at each temperature/concentration and the times were concordant to an acceptable degree. There were a few anomalous runs, which I mentioned in my analysis section, and gave a possible explanation for above. I could have repeated the experiment a further time when I got inconsistent results, e. g. 0. 01 M manganese(II) sulfate(VI), to increase reliability. Extending the investigation The observations I made about the colours during particular runs were solely qualitative. I could broaden the scope of my investigation by using colourimetry to obtain a quantitative measurement of the colour intensity when the reaction was especially faint or dark. I could then compare it to values from the standard reaction to reinforce my observations. I could also use the data logger to measure the times of the colour changes. I could then compare the results from this technique to those from the stopwatch and evaluate the advantages and disadvantages to both methods, and decide which one would be better at producing accurate results. Conclusion Overall, I am satisfied that I have made valid conclusions about the effect of temperature and concentration on the rate of the Briggs–Rauscher reaction. Although I did not fully meet my aim of finding the order of reaction for every reactant, I did discover that the reaction was not typical in this sense, and that the orders of reaction could not easily be found. I did manage to justify parts of the mechanism through the qualitative observations I made.