(5 marks)

We set out to investigate if by increasing the size of the pieces of calcium carbonate, did it react faster with dilute hydrochloric acid.

In my investigation, I found useful information in the book
"Nature Study in Ireland" by Mary Lillaloo, or,
the website "http://www.bbc.co.uk/schools/gcsebitesize/energy.html",
or, "my aunt who is a marine biologist"

You should identify at least four variables/controls. A variable would be something like volume or time that is changing and being recorded during the investigation.  A control is something that needs to be kept fixed in order to make the investigation a fair one. An example of a control would be keeping the temperature fixed for each trial, using the same thermometer for each temperature reading, etc.

You need to have a minimum of three pieces of equipment used in the investigations.  Where chemicals are used, a chemical is usually accepted as an item of equipment.

Generally a minimum of four tasks are required here. These are not the same as the more detailed steps needed for your procedure. Examples of tasks would include:

Any two safety precautions are to be given here. For example:

Give at least five steps taken in conducting the investigation. "Set up the apparatus as shown in the diagram" would probably not be acceptable. More detailed and instructions are required. Number the steps you give. For example:

1. The seeds were soaked in water at room temperature for 24 hours.
2. The quadrat was thrown randomly.
3. The current was measured using the ammeter.
4. The length of wire was measured using a metre-stick.
5. The volume of gas was measured at thirty second intervals.
6. The pH paper was placed into the solution, etc.

Include a table of data where possible. Make two comments about the results obtained. For example:

Here they require one relevant statement on either your data, your calculations or your graph.  A poor statement will obtain four marks. A slightly better statement will obtain seven marks, while a good statement will merit ten marks. For example:

Now you are required to give one relevant conclusion based on either your data, your calculations or your graph.  A poor conclusion will obtain four marks. A slightly better conclusion will obtain seven marks, while a good conclusion will merit ten marks. For example:
"The resistance of the wire depends upon its temperature", "The speed at which a chemical reaction takes place will depend upon the size of the particles" will earn you 10 marks if this is true.

For example:

1. What did you learn from this investigation (Do not repeat anything that you have written down already)
2. How reliable was your data (give a reason)
3. How could you improve this investigation if you were to do it again
4. What sources of error were there (give a reason)

A poor comment will obtain four marks. A slightly better comment will obtain seven marks, while a good comment will merit ten marks. For example:
"The investigation could be repeated at different temperatures", "The reaction could be repeated with different masses/concentrations/volumes of reactants".