Chemistry – Rate of Reaction Coursework
Section 1: Planning
Aim
To find out and analyse what factors affect the rate of reaction between limestone and acid rain.
Background Information
Most materials that are exposed to outdoor conditions are likely to eventually erode due to a natural weathering process. Limestone and marble are two rocks that are often used in the construction of buildings, and this has been so since the 19th century. Both rock types contain a large amount of calcium carbonate. All carbonate materials are likely to erode due to rain. Pure water has a pH of 7, however rain is slightly acidic, with a pH of approximately 5.6. Rain water in some areas has known to be even more acidic, with a pH of 3 or less.
The chemical equation for this reaction is:
Calcium Carbonate + Hydrochloric Acid → Calcium Hydroxide + Carbon Dioxide
CaCo3 + H2SO4 → CaOH2 + CO2`
I know that these three main factors could affect the rate of reaction between limestone and acid rain:
- Temperature
- Surface Area
- Concentration (of solution)
- Pressure (of gas)
However in my experiment I am only going to investigate one of these factors. I have decided that surface area isn’t the best one to choose because I only have 3 different sized marble chips so I wouldn’t get a very large range of results to plot onto my graphs. I have decided to use concentration as my factor to investigate as I believe it will give me a better range of results and more interesting graphs to plot.
This is a preview of the whole essay
Peer Reviews
Here's what a star student thought of this essay
Quality of writing
The punctuation, grammar and spelling are all to a very high level. Format of the text is good with key points being highlighted in bold.
Level of analysis
The candidate begins with a good summary of what the aim of the investigation is and some background knowledge of the subject. They state what factors they could investigate which is good, but they also need to state how they will keep the other factors constant so that they do not affect the experiment negatively. The candidate made some good improvements from noting the effects with the preliminary experiment on the results and takes steps to prevent any errors that may occur which is good. The candidate makes a prediction based with scientific theory which is accurate. The candidate does not provide us with the results, and the method should really be laid out with a bullet pointed system to make it easier to read and a diagram so any other person could easily set up the experiment.
Response to question
Overall a good starting essay, the only problem is that no results are provided and it just outlines how to do the experiment so we cannot get an overall picture of the students grasp of evaluating the experiment in light of their results. A very good pre-liminary experiment is carried out by the candidate which allows errors to be accounted for and to predict how the experiment will go which should be done in all circumstances to make the results more reliable.