rate of reaction between marble chips and hydrochloric acid

Marble Chips / Hydrochloric Acid
Rates of Reaction: Marble Chips and Hydrochloric Acid
Rates of Reaction
PLANNING
AIM
To find if changing the concentration of an acid will increase or decrease the rate of the reaction when marble is dissolved in hydrochloric acid.
PREDICTION
When the concentration of acid increases, more gas will be given off faster. I know this from my trial experiments.
METHOD
Since I will be working with strong acid, I will wear safety goggles while conducting the experiment.
I will use Marble chips all of a small size. I can use a sieve to make sure they are all roughly similar size- about 7mm diameter.
The amount of acid I have decided on is 10ml. And so the amount of marble must be in excess - 3g.
I can measure the speed of the reaction by how much gas is given off. I can measure this in cm3 in a gas syringe. When the experiment takes place, I will take the reading every 10 sec...