How do you determine the initial mass of substance to use?

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

Reply 1

Dstbgre

In my experience as long as its a sensible mass you will be fine i.e. not mg or kg of the stuff.
Also find out what you will be using to collect the gas. Then use the max volume which that can measure to calculate the max number of moles of gas which can be collected then use this to work backwards to find the max mass of copper carbonate to use. Once you have found the max to use then take some off so you have a margin of error.