CP13a

Question 1

Why do both the propanone and acid have to be in large excess to determine the order of reaction with respect to iodine

Answer 1

so that changes in the concentrations of the propanone and acid are negligible and don’t affect the rate

Question 2

What is the role of sodium hydrogen carbonate in this reaction

Answer 2

used to quench the reaction mixture - stops reaction by neutralising acid to be able to determine concentration at a specific time

Question 3

What is the role of hydrogen ions in this experiment and why do they feature in the rate equation

Answer 3

catalyst
catalysts affect rate so therefore appear in the equation

Question 4

What type of rates method is used for this practical

Answer 4

continuous monitoring

Question 5

What graph is plotted for this reaction

Answer 5

concentration against time

Question 6

At what point in the reaction is the indicator added

Answer 6

after the solution turns pale yellow

Question 7

Why is sodium hydroxide not used to quench the solution

Answer 7

the iodoform reaction would take place

Question 8

What is the colour change for this reaction

Answer 8

blue/black to colourless

Question 9

Why is starch not added at the start of the titration

Answer 9

starch and iodine react to form a solid complex which would remove iodine from the solution