Measuring the rate of a reaction by continuous monitoring method

Question 1

How do you meausre rate when the product is gaseous

Answer 1

• volume of gas produced
• or loss in mass

Question 2

How do you measure rate when the product is coloured

Answer 2

colrimetry

Question 3

How is the volume of a insoluble gas measured?

Answer 3

• gas collected under water in an inverted measuring cylinder or burette

Question 4

How is the volume of a soluble gas measured?

Answer 4

• e.g. CO2
• gas syringe attached to a sealed reaction vessel to measure the volume of the gas

Question 5

When dropping a solid reactant into solution then putting the bung on, what errors may occur? how are they minimised?

Answer 5

• gas escape due to tuime to put bung on
• magnesium could be suspended by a string above the acid and the stopper loosened just enogh to release the thread, dropping the magnesium into the acid

Question 6

What is a clock reaction?

Answer 6

measures from start of reaction to the end where a visible (preferably sudden) change occurs

Question 7

What happens in the iodine clock reaction?

Answer 7

• hydrogen peroxide with iodie ions
• small, known amount of thisulfate ions, which contains a starch indicator
• thisolsulfate react with iodine, turning it back to iodide ions, so there is no colour change
• at the instant when all the thisosulfate molecules are used up, free idine is product and the reaction gives a deep blue-black colour with the statch