Investigating Factors Which Affect The Reaction Between Chalk and An Acid

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Investigating Factors Which Affect The Reaction Between Chalk and An Acid

Introduction:

Chalk is just one of many forms that calcium carbonate can take. It is

made of the mineral remains of sea creatures from millions of years

ago. It is quite soft, but solid. It reacts with hydrochloric acid

like this

2 CaCO3 + 2 HCl → CO2 + CaCl2 + H2O

producing Carbon Dioxide, which is what we measure in the experiment.

There are different factors affecting the rate of this reaction, such

as:

* Temperature

* Concentration of acid

* Surface area of chalk

* Pressure

* Light intensity (this is a very small affect so it doesn't really

count and I won't take it into account)

* Whether a catalyst is present (in this experiment there isn't one

anyway)

(Note these factors affect the rate of the reaction, but not the final

amount of carbon dioxide produced.)

Why these factors affect it: higher temperature makes atoms move more

so they are more likely to bump into each other and react. The more

concentration or more volume there is of an acid, the more acid

molecules there are that can react with the chalk. The larger the

surface area of a solid, the more surface there is for acid to collide

with and react with. Higher pressure pushes the molecules closer

together, so it's quicker for them to collide with each other and

therefore react (so raising the pressure is like raising the

concentration). Every reaction needs a little "activation energy" to

make it happen, and when catalysts are added they reduce the amount of

activation energy needed.

I have chosen to do concentration of acid because surface area is

difficult to measure, pressure is hard to do in a school lab, and

temperature could be dangerous e.g. if acid boils it could spit.

Prediction:

I predict that as I strengthen the acid (increase molarity) the

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