Marble Chips And Hydrochloric Acid Lab Report

Rates of Reactionsin Marble Chips Investigation

Aim ---

The aim of this experiment is to discover how the rate of reaction between Marble chips and Hydrochloric acid changes as the concentration of the acid is increased or decreased.

Background ----------

This experiment is using Marble chips and Hydrochloric Acid:

[IMAGE]CaCO3 + 2HCl CaCl2 + H2O + CO2

Hydrochloric Acid

[IMAGE]

+ Carbon Dioxide

Calcium Carbonate + Calcium Chloride + Water

The rate of reaction could be measured by a change in the following:

Colour

Formation of precipitate

Change in mass

Volume of gas evolved.

Time taken for given mass to disappear

pH

I will vary the concentration in 0.5 mol intervals ranging from 0.5 mol to 4.0 mol. Mixing different concentrations of acid with distilled water to make new concentrations changed the variable. E.g. To make 2.0 mol: 20ml of 4.0 mol 2HCl and 20ml of H2O are mixed.

Temperature: As the temperature increases, the particles are given more energy making them move faster and react faster. To maintain the same temperature during the experiment the equipment was held in a laboratory at room temperature (approx. 20°C).

Particle size: When one reactant is solid, the reaction takes place on the surface of the solid. If the surface area is increased then the space for the reaction to take place is increased. To keep this variable constant, medium sized chips were used throughout. The chips were also weighed to confirm that they all had identical masses.

Prediction:

I predict that the results from this experiment when plotted on a graph will create a curved best-fit line. The results therefore will not be proportional. I predict the graphs will have the

The acid was warmer than the other older acids and this could have had some effect on the reaction. Little could be done about it and human error had to be accounted for.

The medium marble chips all came from the same bucket, but these were not all the same size. Even though they were weighed to ensure the same mass, different numbers of chips were in these masses and if there were more there was a greater surface area for the reaction to take place.

The measuring of the quantities of acid required was done carefully using the measuring cylinders, but ensuring the meniscus of the liquid were at the identical level each time was impossible and these tiny errors may have accounted for some anomalies.

The readings were all repeated three times in an attempt to increase accuracy and eliminate anomalous results. In places where the lines have crossed each other, I have concluded that these occurred