AS Chemistry Coursework help needed!

Hi guys,

I am currently doing OCR chemistry AS, and am doing my coursework.

I am planning an experiment to decompose copper carbonate by heating, and collecting the gas released.

The thing I don't understand, that I have seen in previous coursework, is that you have to specify an initial mass of the substance you are decomposing to use and it is usually in a specific range on the mark scheme. How do you determine this mass? I am so confused!!

Thanks for the help,
Dave

bump

Personally I haven't done this experiment, but I have an idea of what you mean. Firstly, you need to write down the balanced symbol equation for the reaction. Then you decide how much gas, on average, you'd want to produce-ie 10cm3, or 25cm3, and work out how many moles of gas that is. Then you work out how many moles of the solid you'd want for that number of moles of gas to be produced, from the balanced equation, and using mass=n x Mr work out the mass of the solid that contains that number of moles.

Hopefully that's what you mean, and that helps. If not, then I don't know what to do =).