Investigating how concentration affects rate of reaction Essay Example for Free

Investigating how concentration affects rate of reaction Essay This means that you would need to use 200ml of the original 0. 01M solution with 50ml of distilled water to make 250ml of 0. 008M solution. Remember to keep all other solutions at a constant concentration throughout. Investigat  the same range of concentrations as was used for potassium bromide, to ensure that a rate equation can easily be found. Making Required Solutions 0. 01M potassium bromate(V): KBrO3: K = 1 x 39. 1 = 39. 1 Br = 1 x 79. 9 = 79. 9 O3 = 3 x 16. 0 = 48. 0 RFM = 167 grams needed = (0. 01 x 167 x 250) 1000 = 0. 4175g dissolved in enough distilled water to make 250ml of solution. 1M Sulphuric acid: H2SO4: H2 = 2 x 1. 0 = 2 S = 1 x 32. 1 = 32. 1 O4 = 4 x 16. 0 = 64. 0 = 98. 1 grams needed = (1 x 98. 1 x 250) 1000 = 24. 525g dissolved in enough distilled water to make 250ml of solution. 0. 0001M phenol: C6H5OH: C = 6 x 12. 0 = 72. 0 H = 6 x 1. 0 = 6. 0 O = 1 x 16. 0 = 16. 0 = 94. 0 grams needed = (0. 0001 x 94 x 250) 1000 = 0. 00235g dissolved in enough distilled water to make 250ml of solution. 0. 01M potassium bromide: KBr: K = 1 x 39. 1 = 39. 1 Br = 1 x 79. 9 = 79. 9 = 119. 0 grams needed = (0. 01 x 119 x 250) 1000 = 0. 2975g dissolved in enough distilled water to make 250ml of solution. Risk Assessment (6) The following risk assessments are based on concentrated solutions of each substance. The concentrations I will be using are much more diluted that the solutions mentioned below to ensure that my experiment is safer. Although some of the acute hazards and symptoms associated with the concentrations I am using will not be as severe as those shown below, the risks are still very serious. For this reason I will still take appropriate precautions and will handle each substance with care. Potassium bromate(V): Type of Hazard Acute Hazards/Symptoms Prevention of Hazard Solving Hazard Fire. Not combustible but enhances combustion of other substances. Gives off irritating or toxic fumes (or gases) in a fire. No contact with combustibles and reducing agents. Water in large amounts. Explosion Risk of fire and explosion on contact with combustible substances and reducing agents. n/a In case of fire: keep drums etc. cool by spraying with water. Inhalation Cough. Sore throat. Breathing protection. Fresh air, rest. Refer for medical attention. Contact with skin Redness. Protective gloves. First rinse with plenty of water, then remove contaminated clothes and rinse again. Refer for medical attention. Contact with eyes Redness. Pain. Safety goggles, or eye protection in combination with breathing protection if powder. First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then take to a doctor. Ingestion Abdominal pain. Diarrhoea. Nausea. Vomiting. Do not eat, drink, or smoke during work. Wash hands before eating. Rinse mouth. Give a mixture of activated charcoal in water to drink. Induce vomiting if person is conscious. Refer for medical attention. Spillage n/a n/a Sweep spilled substance into sealable containers; if appropriate, moisten first to prevent dusting. Carefully collect remainder then remove to safe place. Do not absorb in sawdust or other combustible absorbents. Storage n/a Separated from combustible and reducing substances, powdered metals and incompatible materials. See Chemical Dangers. n/a Sulphuric acid: Type of Hazard Acute Hazards/Symptoms Prevention of Hazard Solving Hazard Fire Not combustible. Many reactions may cause fire or explosion. Gives off irritating or toxic gases in a fire. No contact with flammable substances. No contact with combustibles. No water. In case of fire in the surroundings: powder, foam, carbon dioxide. Explosion Risk of fire and explosion on contact with bases, combustible substances, oxidants. n/a In case of fire: keep drums etc. cool by spraying with water but no direct contact with water. Inhalation Corrosive. Burning sensation. Sore throat. Cough. Struggling to breathe. Shortness of breath. Ventilation or breathing protection. Fresh air, rest. Half-upright position. Artificial respiration may be needed. Refer for medical attention. Contact with skin Corrosive. Redness. Pain. Blisters. Serious skin burns. Protective gloves. Protective clothing. Remove contaminated clothes. Rinse skin with plenty of water or shower. Refer for medical attention. Contact with eyes Corrosive. Redness. Pain. Severe deep burns. Face shield or eye protection in combination with breathing protection. First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then take to a doctor. Ingestion Corrosive. Abdominal pain. Burning sensation. Shock or collapse. Do not eat, drink, or smoke during work. Rinse mouth. Do not induce vomiting. Refer for medical attention. Spillage n/a n/a Do not absorb in saw-dust or other combustible absorbents. Personal protection: complete protective clothing including self-contained breathing apparatus. Do not let this chemical enter the environment. Storage n/a Separated from combustible and reducing substances, strong oxidants, strong bases, food and feedstuffs, incompatible materials. May be stored in stainless steel containers. Store in an area having corrosion resistant concrete floor. n/a Phenol: Type of Hazard Acute Hazards/Symptoms Prevention of Hazard Solving Hazard Fire Combustible. No open flames. No contact with strong oxidants. Alcohol-resistant foam, powder, water spray, carbon dioxide. Explosion Above 79i C explosive vapour/air mixtures may be formed. Above 79i C use a closed system, ventilation. In case of fire: keep drums etc. cool by spraying with water. Inhalation Sore throat. Burning sensation. Cough. Dizziness. Headache. Nausea. Vomiting. Shortness of breath. Laboured breathing. Unconsciousness. Avoid inhalation of fine dust and mist. Ventilation or breathing protection. Fresh air, rest. Half-upright position. Refer for medical attention. Contact with skin Easily absorbed. Serious skin burns. Numbness. Convulsion. Collapse. Coma. Death. Protective gloves. Protective clothing. Remove contaminated clothes. Rinse skin with plenty of water or shower. To remove substance use polyethylene glycol 300 or vegetable oil. Refer for medical attention. Wear protective gloves when administering first aid. Contact with eyes Pain. Redness. Permanent loss of vision. Severe deep burns. Face shield, or eye protection in combination with breathing protection. First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then take to a doctor. Ingestion Corrosive. Abdominal pain. Convulsions. Diarrhoea. Shock or collapse. Sore throat. Smoky, greenish-dark urine. Do not eat, drink, or smoke during work. Wash hands before eating. Rinse mouth. Give plenty of water to drink. Do not induce vomiting. Refer for medical attention. Spillage n/a n/a Sweep spilled substance into sealable containers; if appropriate, moisten first to prevent dusting. Carefully collect remainder then remove to safe place. Personal protection: complete protective clothing including self-contained breathing apparatus. Do not let this chemical enter the environment. Storage n/a Separated from strong oxidants, food and feedstuffs. Keep in a well-ventilated room. n/a Potassium bromide: The hazards for this substance are almost negligible, especially for the low concentrations that I will be using. However, protective goggles will still be worn to avoid contact with eyes, as this could cause irritation. This substance could also cause some discomfort if ingested, so I will take be very careful to ensure that this doesnt happen. Method for Investigating Temperature Change Extra Apparatus Reason For Use Size/Concentration Heating plate Used to heat the mixture to different temperatures during the reaction.n/a Beakers Used as a water bath to heat the mixtures evenly. 500ml Boiling tubes Used to hold reacting mixture whilst it is heated or cooled to the desired temperature. n/a Ice cubes Used to cool the water bath to temperatures below room temperature. n/a Thermometer Used to measure the temperature of the mixture so that it can be kept constant throughout the reaction. n/a Method 1. Set the apparatus up as was done in the experiment investigating concentration change. However, this time use a heating plate rather than a magnetic stirrer so that temperature can be adjusted. 2. Mix 5cm3 of potassium bromate(V) solution, 5cm3 of sulphuric acid solution and 5cm3 of phenol solution in a boiling tube and add 4 drops of methyl orange indicator. 3. Add 5cm3 of potassium bromide to a separate boiling tube. 4. Fill a large beaker with water and place it on top of the heating plate and set it to the required temperature. To achieve cooler temperatures put ice cubes into the beaker and monitor the temperature using a thermometer. Place the boiling tubes containing the correct solutions in the water bath so that they are also heated or cooled to this temperature. 5. Mix the two solutions and start the stopwatch. Record the time taken for the solution to go colourless. Ensure that the temperature of the water is kept constant. This can be done by having a thermometer in the beaker. Although the higher temperatures should be easily maintained by the heating apparatus, lower temperatures must be kept constant by adding more ice cubes if required. 6. Repeat 5 times with each temperature to ensure accurate and fair results. Results With Respect to Potassium Bromate(V) The table below shows my results when varying the concentration of potassium bromate(V): Concentration of Potassium Bromate(V) (mol/dm-3). Time Take For the Mixture to Turn Colourless (seconds) Repeat 1 Repeat 2 Repeat 3 Repeat 4 Repeat 5 Average Reaction Rate (seconds-1) Graph 1 on the next page shows the concentration of potassium bromate(V) plotted against the average time taken for the solution to turn colourless. From this graph I can see that there is a negative correlation because as concentration is increased, the time taken for the solution to turn colourless decreases. However, this graph does not provide enough information to work out the rate equation data for potassium bromate(V). For this, I had to draw up a graph of concentration against reaction rate. Reaction rate is worked out using the following equation: Reaction Rate = 1 Time This is presented in Graph 2. Graph 2 has a line of best fit which is a straight diagonal line, rather than a curve. It also shows that there is a positive correlation between concentration and reaction rate, as when concentration of potassium bromate(V) is increased, reaction rate increases. I could draw the line of best through the origin at point (0,0) as I know that if the concentration is 0M then the reaction will not occur the reaction rate will be 0seconds-1 (this can be applied to all other graphs of concentration against reaction rate that I have drawn). I decided to draw the majority of my graphs using a computer to plot the axes and points, and drawing the line or curve of best fit by hand. The computer can provide better accuracy than I can as far as drawing the axes and plotting the points is concerned. However, I believe that I can provide more accuracy when drawing the line or curve of best fit. My line of best fit suggests that the reaction, with respect to potassium bromate(V), is first order. This means that that rate equation so far is as follows: Rate = k[BrO3] Results With Respect to Potassium Bromide The table below shows my results when varying the concentration of potassium bromide: Concentration of Potassium Bromide (mol/dm-3) Time Take For the Mixture to Turn Colourless (seconds) Repeat 1 Repeat 2. Repeat 3 Repeat 4 Repeat 5 Average Reaction Rate (seconds-1) The line of best fit is once again a straight diagonal one. This shows that there is again a positive correlation between concentration and reaction rate.