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Preparing for Heat from burning alcohol IAA

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Preparing for Heat from burning alcohol IAA

  1. 1. Heat from burning alcohols <ul><li>Ethanol: C 2 H 6 O </li></ul><ul><li>Propan-1-ol: C 3 H 8 O </li></ul><ul><li>Propan-2-ol: C 3 H 8 O </li></ul><ul><li>Butan-1-ol: C 4 H 10 O </li></ul>
  2. 2. 1. What are you trying to find out in this investigation? <ul><li>The masses of different alcohols needed to burn to raise the temperature of 100 cm 3 by about 10 o C </li></ul>
  3. 3. 2. What measurement did you make? <ul><li>Measured mass of alcohol, splint burner and cap before burning </li></ul><ul><li>Measured mass of alcohol, splint burner and cap after burning </li></ul><ul><li>To find mass of alcohol burned to raise temperature of water 10 o C </li></ul><ul><li>Measure the initial and final temperature of the water </li></ul>
  4. 4. 3. How did you make sure that you collected valid data and reliable data? <ul><li>Valid </li></ul><ul><li>For each alcohol, volume of water kept constant at 100cm 3 </li></ul><ul><li>For each alcohol, temperature rise was 10 o C </li></ul><ul><li>For each alcohol, the splint was lit below the flask to minimize heat loss to surroundings </li></ul><ul><li> For each alcohol, we ensured that the flame was touching the conical flask to minimize heat loss to surroundings </li></ul>
  5. 5. <ul><li>Reliable </li></ul><ul><li>Repeat for each alcohol the experiment twice and then take an average of mass burnt from each alcohol to raise the temperature of water by 10 o C </li></ul><ul><li>Repeat until agreeing values are obtained </li></ul>
  6. 6. 4. Describe the pattern shown on the graph <ul><li>- As number of carbon atoms in the molecules increase then the mass of alcohol used decreases </li></ul><ul><li>- Negative correlation between them </li></ul>
  7. 7. 5 . It is thought that a better way to represent this data is by joining the points with straight lines or by drawing a bar chart. Explain why <ul><li>Usually: </li></ul><ul><li>Bar charts: used to present discrete data </li></ul><ul><li>Line of beft fit: Used to represent continuous data in order to reveal the relationship between variables </li></ul><ul><li>For our practical data the number of carbon atom is discrete and the mass used is a continuous variable. Thus, a bar chart might be appropriate. </li></ul>
  8. 8. 6. How could the validity and reliability of your results be improved? <ul><li>Reliability: </li></ul><ul><li>-By repeating practical for each alcohol to see if mass readings in each case are about the same. </li></ul><ul><li>Valid: </li></ul><ul><li>Test a wider range of alcohols to see if pattern shown on the graph holds. </li></ul><ul><li>Use insulation to reduce heat energy lost to the surroundings </li></ul><ul><li>Record masses on a balance weighing to 3 decimal places </li></ul>
  9. 9. 7. Which one of the alcohols you used is the best fuel? Use the results from your investigation to explain your answer <ul><li>Butanol </li></ul><ul><li>Gives out greatest amount of heat for a given mass of alcohol burned </li></ul><ul><li>Mass of alcohol burned is the smallest out of these investigated </li></ul>
  10. 10. 8. What other information is needed before recommending this alcohol to be used a fuel? <ul><li>Flammability </li></ul><ul><li>Toxicity/pollution </li></ul><ul><li>Performance in a car engine </li></ul>