Rates of reaction Essay Example for Free

Rates of reaction Essay The two equations can then put together to give an overall rate equation: R[Na2S2O3]x[HCl]Y Experimentally I will be changing the concentrations of each the reactants independently and then calculating the rate for each concentration. From these rates I will be able to draw a log graph of rate against concentrations and from my calculation I can find the orders for each of the reactants. Variables The independent variable in the experiment is the initial concentrations of Sodium Thiosulphate and Hydrochloric Acid. I will be changing this variable and seeing how it affect the time taken for the reaction to take place and therefore how the concentration affects the rate of the reaction. However as only one variable can be changed I will keep one reactant constant whilst changing the other to get a fair set of results. This will show me the affect of each reactant on the rate independently. The dependent variable is the one that will be monitored in the reaction. The dependent variable is the time taken for the reaction to take place which can be used to calculate the rate of the reaction. The method I will be using is by seeing how long it takes for a black cross underneath the conical flask to disappear which will be the point in all the reactions where the concentration of the sulphur precipitate is equal and so will the rate can be fairly calculated. To reduce errors I will need to use my preliminary results to find a volume that will give a long enough time to measure accurately, but not too long to affect the rate which is calculated by dividing initial concentration by time. These graphs show how if the time taken for the reaction to reach a specific concentration is too long it will not be a true reflection on the actual initial rate of the reaction. The first variable that must be controlled is the temperature of the reactions. This is because temperature will affect the rate of the reaction as a higher temperature will cause an increase in the rate. If the temperature varies between reactions it will have an affect on the results. To try and insure the same temperature is used I will have all reactants at room temperature and carry out all the reactions in one lesson. Another control is the the volume of reactants used and the depth of the solution. If this is changed the amount of precipitate that will need to be observed through will change and therefore the concentration at which the cross disappears will be different. To control this the same volumes will be used and the same conical flask will be used and therefore the depth will be the same. Similarly the cross used will need to be the same as a thicker cross would mean it will disappear at a different concentration of sulphur and the results will not be fair. Finally I will not shake or move the conical flask once the reactants have been put together as this again might affect the rate of the reaction. Equipment 1. 200cm3 of Na2S2O3 1. 200cm3 of HCl 2. 10 x 50cm3 beakers 3. 2 x Graduated Pipettes 4. Conical Flask 5. Stopwatch Method 1. Start by making the concentrations, using a graduated pipette measure out the correct volumes of Sodium Thiosulphate and put into 5 small 50cm3 beakers. Then add the corresponding amounts of distilled water and label with the correct concentration. 2. Secondly draw a black cross onto a piece of paper which is no bigger than the base of the conical flask, place the conical flask on top of the flask. 3. Using another graduated pipette, place 25cm3 of 2M hydrochloric acid into the bottom of the conical flask. 4. Whilst standing above the conical flask, looking directly down, simultaneously pour the first concentration of Na2S2O3 into the conical flash and start the stopwatch. 5. Keep observing and when the yellow precipitate causes the cross to completely disappear stop the stopwatch. 6. Record the time taken, wash out the conical flask thoroughly and repeat from step 3 but using the next dilution until all the concentrations have been reacted and recorded. 7. Repeat all results and average times. 8. Secondly replace the Sodium Thiosulphate with the HCl and copy above steps by measuring out correct concentrations and place into 5 more 50cm3 beakers. 9. This time add 25cm3 of Na2S2O3 into the bottom of the conical flask before recording the time taken for the cross to disappear again, for all the concentrations. 10. Repeat all results again for HCl concentrations. Initial Rates can then be calculated. Dilution Tables Na2S2O3 Concentration / moldm-3 Na2S2O3 (1M) / cm3 Distilled Water / cm3 1 HCl Concentration / moldm-3 HCl (2M) / cm3 Distilled Water / cm3 Safety Points As concentrated Hydrochloric acid will be used make sure eye and hand protection is worn. In case of contact, immediately flush skin with plenty of water for at least 15 minutes and with eye contact get medical attention immediately. Sulphur is also present so make sure the room is well ventilated to allow fumes to escape. Take care with glass wear, such as pipettes as they are fragile and may break easily. If broken clear up all glass immediately. Time Taken for Cross to Disappear / s Concentration of Na2S2O3 / moldm-3 1 2 Average Rate / moldm -3 s -1 logRate / log moldm -3 s -1 logconc. / log moldm-Time Taken for Cross to Disappear / s Concentration of HCl / moldm-3 1 2. Average Rate / moldm Analysis After drawing a graph of logRate against logConcentration and using the calculations in my plan, the gradient of the line gave me a value of 0. 957 which taking into account experimental error shows the order of the reaction of Sodium Thiosulphate is 1. Also when carrying out the investigation for how the rate changes with the concentration of HCl there is no noticeable change in rate when the concentration varies. Therefore I didnt draw a graph, as the table shows HCl concentration doesnt affect the rate of the reaction and must be zero order. I can therefore deduce that the rate equation for this reaction is: Rate ? [Na2S2O3]1 and Rate ? [HCL]0 Rate = C x [Na2S2O3] where C is a constant which is proportional to the rate constant. The reason why the actual rate constant, k, can be calculated is because in the experiments the change in concentration cannot be calculated. However this always the same value as it is the concentration at which the cross disappeared and therefore the rate was proportional to 1/time. The intercept of the graph is equal to logC, -1. 02, therefore C = 10-1. 02 = 0. 095s -1. To conclude the results show that the rate of the reaction between Sodium Thiosulphate and Hydrochloric Acid is directly proportional to the concentration of Sodium Thiosulphate. This gives evidence to the mechanism of the reaction. In a most reactions the mechanism is not made up of one step but a series of intermediate stages where molecules form and break down. Each of these steps will have a rate which is due to how many molecules are colliding. For example if 2 molecules must collide to for one product the reaction will be 2nd order. However the overall order for the reaction cannot be calculated using the stoichiometry in the overall equation. This is because the rate is determined by the rate of the slowest step of the mechanism, known as the rate determining step. In this reaction although 2HCl molecules are needed for the reaction to take place; however from the kinetics that I found HCl has no effect on the rate and is zero order. Therefore the slowest step in this reaction is the breakdown of 1 Sodium Thiosulphate molecules as the reaction is 1st order. Evaluation. I feel the results I obtained allowed me to draw a graph and come to valid conclusions and be confident about calculating the order and rate equation for this reaction. I didnt have any obvious anomalies from my graph however there are some variations that meant I couldnt calculate a rate of exactly 1. Also from my table of results for changing the concentration of HCl, where all the rates must be the same for difference concentrations, there is a anomaly with the 2. 0moldm-3 concentration. A limitation of my procedure was the way in which the rate was calculated using the disappearing cross method. This involves human judgement rather than a qualitative value that can be used to calculated the rate. There will also be an accuracy issue as there is a reaction time in realising the cross has disappeared and stopping the stopwatch. Another limitation of the procedure at the start of the timing and I had to add the chemicals together and start the stopwatch. This again causes an error in the actual time period taken for the cross to disappear. Another error is in the variation of temperature. As well as environmental variations in temperature the reaction was exothermic and heat is produced. When the temperature increases the k constant will increase, this is because the molecules have more kinetic energy and there is a higher probability that they will collide and react. This means its is hard to control this factor which is affecting the rate of the reaction. There are also many accuracy errors caused by percentage error in measuring. There is a time error in the time taken when the cross disappears and the delay in stopping the time. When using the graduated there was an error of 0. 05/20 = 0. 25% error, human reaction time is about 0. 2/9. 34 = 2. 1%. To reduce this error I would choose another method of measuring the rate. Instead of using the cross method I would use a light intensity machine that could measure the change in colour over a period of time and stop and start timing when it had reach a certain value. This quantitative method of measuring should make the results more accurate. To control the temperature I could use a large water bath which could control the temperature throughout the reaction. Another method that could be used is to measure the products formed. The easiest would be using a gas syringe to measure the amount of SO2 formed. This again would give a more quantitative results and increase the accuracy and reliability.

Legalization of Marijuana Essay -- social issues

Legalization of Marijuana Take A Closer Look Those who oppose legalizing marijuana tell us that legalizing it would be seriously detrimental. Are they looking at the facts? Or do they just believe the same myths that our parents created when they were trying to stop us from becoming drug addicts? Let&rsquos take a closer look at the facts. Violence surrounding drug dealing would be lessened by legalizing marijuana because small time drug dealers would essentially be forced out of business. Larger companies who could produce high quality marijuana at lower cost would prevail. Most people would buy from these companies because they would know the product was free of adulterants and would contain no poisons. Wars between dealers of marijuana would end, and the sale of marijuana could be monitored by government the same way as essentially any other legitimate business. Sellers would be made accountable and a culture of responsibility would be formed. Desperate acts of theft and violence associated with its distribution would disappear as the black market disappears. Additionally, marijuana abusers who are currently being forced to live a life of shame and secrecy could openly seek help. Dangerous drugs such as crack cocaine and LSD are consistently placed in the same category as marijuana. These drugs are admittedly dangerous, but research has never been able to identify a link between crime and marijuana. Countless Americans have been branded as criminals and thrown into prison for merely possessing or smoking marijuana. Truly violent criminals are often paroled early for sheer lack of prison space because users of marijuana occupy the space. Why not leave the rapists and murderers in prison and let marijuana users engage in a relatively mild form of personal stimulation? Marijuana is safe and effective for medical use. Studies have proven that it is effective in reducing nausea and vomiting and that it can stimulate the appetite. This could help cancer and AIDS patients who face emaciation. Marijuana reduces tremors, restores balance, stops muscle spasms, restores bladder control, and restores speech and eyesight for multiple sclerosis patients. It can even prevent epileptic seizures. It can also alleviate pain and sometimes stop the progression of glaucoma because it reduces intraocular pressure. Marijuana is relatively harmless. Re... ... the time of purchase (as well as any retailers in between). The companies making the cigarettes would also have to pay income taxes. As marijuana has many medical uses and is fairly expensive ($160 to $400 per ounce), pharmaceutical companies also stand to make a profit. Drug paraphernalia could be openly sold and profits could be made there as well. The court system would profit as well. Courts would not be burdened by all of the marijuana cases that come before it. The cost of imprisoning marijuana users is enormous. If they were not convicted to begin with, we wouldn&rsquot need a place to put them. The war on drugs is accomplishing as much by chasing marijuana users as a fire fighter would by trying to put out a forest fire with one fire truck. If it is fought back in one place, it pops up in another. Drug enforcement officials are wasting their time and money trying to fight marijuana use. If marijuana were legalized, the money could be better concentrated on keeping minors off drugs. Achievable objectives could be set for law enforcement. Illogical patterns of law enforcement could end and a more responsible approach to controlling marijuana could be developed.

Understanding the Concept and Process of Marketing

Personal Development Plan |Column 1 |Column 2 |Column 3 |Column 4 |Column 5 |Column 6 |Column 7 | | | | | | | | | | | |SKILL |CURRENT |TARGET |DEVELOPMENT |CRITERIA FOR |TIME SCALE |EVIDENCE | | | |PROFICIENCY |PROFICIENCY |OPPORTUNITY |JUDGING SUCCESS | | | | | | | | | | | | |PRIORITY No 1. |Presentation skills |Competent enough for classroom but |Confident classroom |Make a presentation in Dr |Achieve at least a B Grade for my end |By the end of the |See â€Å"Self Assessment Template – | | | |nervous. Not professional standard. presenter |Smith’s tutorial group |of project presentation for Dr Patel |academic year |Presentation Skills† | | | | | | | | | | |PRIORITY No 2. |Written Skills |Technical descriptions ok but lack |Good descriptive writing|Show some of my work to |Achieve a 2. 1 in the Humanities |During my second year |See â€Å"Self Assessment Template – | | | |flair in presenting my â€Å"critical |and satisfactory |College Writing Fellow; | Programme assessments.Writing | |Communication Skills† | | | |thinking† |critical writing |prepare better essays for my |Fellow's opinion. My improved level of| | | | | | | |Humanities class. |confidence as writer. | | | | | | | | | | | | |PRIORITY No 3. Commercial Awareness |Interested in commercial issues, but |Practical knowledge |Participate in an industry |Find ; complete internship programme; |During the Summer |See â€Å"Self Assessment Template – | | | |do not have practical awareness | |summer internship programme |be able to talk † real business† with |Vacation period |Placement† | | | | | | |my tutor | | | | | | | | | | | | |PRIORITY No 4. Team working Skills |Poor – dislike working in teams, hate |Reliable and positive |Become a Student Union |Help organise a Society event; note |During my third year |See â€Å"Self Assessment Template – | | | |trusting my marks to others; hate |team member; competent |Society member; read about |how many of the skills I read about | |Teamwork† | | | |having to compromise my ideas |teamplayer |teamwork |were applied by me. Enjoy the | | | | | | | | |experience. | | | | | | | | | | | |PRIORITY No 5. |Leadership Skills |Lacking in confidence; not good at |Confident leader who can|Volunteer to lead on Spring |Group's satisfaction with me; project |During the Spring Term |See â€Å"Self Assessment Template – | | | |delegating and monitoring. |delegate |term group project. |mark; lecturer's feedback; my level of| |Tutorial† | | | | | | |confidence. | | |

1776 Essay - 605 Words

Abraham Wu Jeremy Chandruc/ Randolph Fodali US History I 9 September 2013 Booker T. Washington once said, â€Å"Success is to be measured not so much by the position that one has reached in life as by the obstacles which he has overcome.† In 1776, by David McCullough, this quote truly resonates the fact that it is the little things that count, as not necessarily the big picture. Although there are many pitfalls the Americans go through during the course of this story, the outcome of the war would be a positive success to the Americans. As a result, good leadership is a very important factor in accomplishing a goal. Also, encouragement is a big help when it comes to boosting a soldier’s morale. Furthermore, endurance is vital to an army†¦show more content†¦This statement by the wounded soldier fueled John’s spirit and drove fear out of his mind. He can fight bravely without worrying about being scared and not becoming distracted by war. Moreover, as encouragement starts the fighting spirit in soldiers, endur ance and perseverance keeps it going. Encouragement and endurance go hand in hand because each benefits the other, and both will fail if one does not help the other. People such as George Washington showed great perseverance during the course of the war. As a result, the author wrote that, â€Å"Without Washington’s leadership and unrelenting perseverance, the revolution almost certainly would have failed† (294). This shows that Washington’s importance as a leader is crucial that pushes people on to do better than before. Because of this, endurance is vital to a war’s progress. In conclusion, a person with good leadership, encouragement, and a lot of perseverance helps soldiers and others achieve many goals. Washington is the perfect man to become a leader of the Continental Army because of his personality. Also, something little could make a big impact on someone’s life, such as the wounded soldier. Further, endurance keeps everyone on the right t rack and it makes the problem seem easier for every person fighting in the war. Because of the little victories, the war isShow MoreRelatedEssay on A.P.U.S.H. 1776626 Words   |  3 PagesEssential Questions 1. Why did Americans choose not only to break from Britain, but adopt a republican form of government in 1776? What Republican ideas did they share, and what did they disagree about? The Americans chose to break from Britain for a lot of different reasons. But the main reason was they wanted freedom from parliament; they did not want to be governed from overseas, they got sick and tired of the taxation and laws. 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Also the book gives a very detailed and informativeRead MoreEssay on Development of the American Identity Between 1750 and 1776919 Words   |  4 PagesKeum Yong (Andrew) Lee DBQ – Score 8/9 (95) In what ways and to what extent did the â€Å"American identity† develop between 1750 and 1776? Though the American colonists had not achieved a true, uniform sense of identity or unity by 1776, on the eve of Revolution, the progress towards unity and the inchoate idea of an â€Å"American† between 1750 and 1776 is inevitable in both existence and significance. Previous to the French and Indian War, America as a whole had been, more or less, loyal mercantile-based