Measuring Reaction Rates

How do you calculate the rate of reaction?

Rate of Reaction= amount of reactant used or product formed/ time

When would you measure the rate of reaction by finding the time taken for a precipitate to form?

When the product is a precipitate that clouds a solution. (you can use the cross method and time how long it takes for the solution to go opaque)

How do you measure the rate of reaction by finding a change in mass?

• When the product is a gas, the rate of formation can be measured using a mass balance

• When the reaction starts, start a stop clock and read off the mass at regular time intervals.

• When the mass stops decreasing, you know the reaction stopped

How do you measure the rate of reaction by using gas volume?

• If a gas is given off during a reaction, you can measure reaction rate by collecting it in a gas syringe and recording how much you’ve got at regular time intervals

• Start a stop clock when the reaction starts and read off the volume of gas in the syringe at regular time intervals. When the volume stop increasing, the reaction has stopped.

• No gas escaped so this method can be used for reactions that produce toxic or flammable gases