This apparatus is placed on a balance and the mass of the flask and its contents is read.
To start the reaction, the flask is gently lent to one side, causing the card to fall and the marble chips and acid to mix.
Students answer questions about the variables and calculate the averages before drawing a graph.
They then explain what the graph shows and use collision theory to explain it.
You can continue in a broader context by introducing some background theory and descriptions of the factors or VARIABLES which may have an effect on the rate of the reaction you are studying (include briefly factors which might not apply). Is there any other factor for the reaction you are studying?
In your 'method' description use the correct units or descriptors. will any of the reactants or products be affected by change in temperature or pressure? there are several reasons why the same acid should be used if its a reactant in the investigation, e.g.
A piece of cotton wool is placed in the neck of the flask to allow carbon dioxide gas to escape. Take readings of mass loss over a time interval, e.g. To find the actual rate we plot the loss in mass (grams) against time (seconds) As with the previous experiment, the steepest part of the curve is at the start, hence the fastest part of the reaction is at the start.
Gradually the curve becomes less and less steep as the reaction slows down.
Hence, these results show that an increase in concentration increases the rate of a reaction.
As you can see, the greater the concentration of the acid used in a reaction the steeper the curve and the shorter the reaction time.