effect of surface area on a rate of reaction

Hydrochloric acid and marble (CaCO3) react to form carbon dioxide gas. The gas can be captured and measured using a gas syringe. A position sensor can be attached to the syringe to record the rate of the reaction. This experiment shows the effect of surface area on the reaction. The effect of acid concentration could also be explored.

What you need

Clamps, bosses and stands, marble pieces (large, medium and small sizes), 1M hydrochloric acid HCl, flask, bung, delivery tube, a good gas syringe, interface, position sensor. alt

Setting up
Set up the flask, position sensor, the gas syringe and 1g of large marble pieces.
Connect the sensor to the interface. When you start your sensing software it should recognise the sensor – otherwise you will have to do this yourself.
You may want to calibrate the sensor so that the computer displays the volume of the syringe directly. If so, find the calibration feature in the software and enter the volumes for the upper and lower limits of the position sensor movement – like a two-point calibration.
Set up the software to record for 90 seconds. Start recording and immediately add 5cm3 acid to the marble in the flask.
Repeat using different sized marble pieces.

Questions
How does the graph show the progress of the reaction?
When was the reaction at its fastest? How can you tell?
Which part of each graph best shows how fast the reaction was working?
Calculate the average gradient of each of your graphs to compare them.

It might help to overlay (merge together) the results of several experiments on one set of axes.