Measuring Rates of Reaction Flashcards
What are the 3 ways of measuring rate of reaction?
1) Precipitation
2) Change in mass
3) The volume of gas given off
What is the formula for rate of reaction?
= (Amount of reactant used OR Amount of product formed) / time
When would you use precipitation to work out the rate of reaction?
When the product of the reaction is a precipitate which clouds thee solution
And if the initial solution is rather translucent
Describe the process of ‘precipitation’ for calculating the rate of reaction
Observe a mark through the solution and measure how long it takes for it to disappear.
The quicker it disappears the quicker the reaction
What is the issue with precipitation?
The result is subjective - different people might not agree over the exact point when the mark ‘disappears’
Describe how the method ‘change in mass’ works
1) Measuring the speed of a reaction that produces a gas can be carried out on a mass balance
2) As the gas is released the mass disappearing is easily measured
3) The quicker the reading on the balance drops, the faster the rate of reaction
How would you present the data from a ‘change in mass’ experiment?
A Rate of Reaction graph
Name 1 advantage and 1 disadvantage of the ‘change in mass’ method
advantage: Most accurate of the 3 methods because the mass balance is very accurate
disadvantage: It release gas straight into the room
Describe how the method ‘The volume of gas given off’ works
1) Involves the use of a gas syringe to measure the gas give off
2) The more as given off during a time interval, the faster the reaction
How would you present the data from a ‘The volume of gas given offs’ experiment?
A graph of gas volume against time elapsed could be plotted to give a rate of reaction graph
Name 1 advantage and 1 disadvantage of the ‘The volume of gas given offs’ method
Advantage: accurate to the nearest ml - pretty accurate
Disadvantage: If the reaction is vigorous, you can easily blow the plunger out the end of the syringe - take care
