Methods of Measuring the Rate of Reactions

What are the three methods of measuring rate of reaction?

1. Precipitation and colour change

2. change in mass

3. volume of gas

How to find rate of reaction by observing colour change/precipitation?

1. Place a black cross under the conical flask

2. Add reactants and start timer and look into the flask from above

3. Stop timer when color stops changing or precipitate stops forming and you can no longer see the cross

What are the disadvantages of observing colour change/precipitation?

results are subjective

cannot plot rate of reaction graph

How to find rate of reaction by change in mass?

1. Place a conical flask on a mass balance

2. Add reactants and place a cotton wool to prevent acids spitting out and start timer

3. stop the timer when the reading on the mass balance stays the same

What are the disadvantages of finding rate of reaction by change in mass?

releases gas into room

What are the advantages of finding rate of reaction by change in mass?

most accurate since mass balance accurate

How to find rate of reaction by volume of gas given off?

1. Mix reactants in a conical flask and attach a cork stopper and delivering tube to a gas syringe

2. Start timer and stop when the syringe has stopped moving

What are the advantages of finding rate of reaction by volume of gas given off?

accurate gas syringe

take measurements at regular intervals to plot graph

What are the disadvantages of finding rate of reaction by volume of gas given off?

if reaction is too vigorous, it can blow plunger out of syringe

What does the reaction between magnesium and HCl produce?

hydrogen gas

How to find the rate of reaction of magnesium and HCL?

volume of gas method

What does the reaction between Sodium Thiosulfate and HCl produce?

cloudy yellow precipitate