In my coursework I will be mainly concentrating on the reaction between dilute hydrochloric acid with marble chips (calcium carbonate). Calcium carbonate (marble chips) + hydrochloric acid ==> calcium chloride + water + carbon dioxide CaCO3(s) + 2HCl (aq) ==> CaCl2 (aq) + H2O (l) + CO2 (g)
The aim of the experiment is to investigate how the concentration of hydrochloric acid affects the rate of reaction with marble chips, i.e. how quickly/how much hydrogen is produced.
Firstly I would like to establish the term rate of reaction', the term means how fast a reaction occurs it could also mean in other aspects how slow the reaction occurring takes place. There are a number of factors that determine the rates of reaction, listed below are the factors affecting the rate of reaction: (a) the solution concentration,
(b) the temperature of the reactants,
(c) the size of the solid particles (surface area effect),
(d) a catalyst
A chemical reaction can only occur between particles if only they collide he reactant particles must collide therefore this only occurs in the collision theroy, the collision theory is the process in which reactant particles collide with each other, the collision must have enough energy for the particles to react. The minimum energy needed for particles to react is called the activation energy, however not all particles bring about a chemical change. More collision increases the rate of reaction.
Temperature increases the number of collisions, as the temperature is increased the particles move quicker. Reactions get faster as the temperature is increased in this case the same mass of gas would be given off because you still have the same quantities of everything in the mixture.
As a catalyst is placed in a chemical it speeds up a reaction without changing the original solution in a chemical., therefore in practical it looks like the diagram below:
The size of the particle also has an affect on the rate of reaction, in this case if a solid particle is broken down into smaller pieces the rate of reaction increases, hence if the particles are large the rate of reaction decreases, The speed increase happens because smaller pieces of the same mass of solid have a greater surface area compared to larger pieces of the solid. Therefore the greater the surface area the faster the rate if reaction.
Safety: During the practical a number of measures have to be taken, to determine that the experiment is carried out safely and precisely, these are: Safety goggles to be worn at all times to ensure no chemicals make contact with eyes. Wear a lab coat, so no corrosive chemicals come into contact with skin and clothes, as well as spillages. Avoid contact with any chemicals, as they can be harmful in a number of ways. Tie long hair back.
Make sure you have no loose fitting clothes, jewellery etc hanging around Place bags and overcoats in suitable place.
Not to eat or drink in the lab.
If using Bunsen burner make sure not near flammable gases. If using Bunsen burner must use a safety mat, make sure that its nowhere near the apparatus. Hypothesis: If you increase the concentration of the reactants, the reaction becomes faster, increasing the concentration increases the chances of particles hitting each other, increasing the number of collisions, hence increases the rate of reaction therefore, I predict that if I increase the concentration of the hydrochloric acid the rate of reaction will also increase.
Dilute Hydrochloric acid