When copper (II) nitrate is heated, it decomposes according to the following equation:
2Cu(NO3)2(s) --> 2CuO(s) + 4NO2(g) + O2(g)
When 20.0g of copper (II) nitrate is heated, what mass of copper (II) oxide would be produced? What mass of NO2 would be produced?
I take it this is the question you're stuck with. I do it like this
1.) Write out the equation with any info you know underneath:
2Cu(NO3)2 --> 2CuO + 4NO2 + O2
20g
2.) Work out molar amounts of any substances with known masses
mol Cu(NO3)2 = mass/Mr = 20.0/187.5 =0.1066666....
3.) Deduce the reacting ratio between the substance you have info for and the one you want info for
2Cu(NO3)2 : 2CuO
1 : 1
Therefore the moles are equal and moles of CuO is 0.1066666
4.) Calculate the mass of what you want
mass= moles x Mr = 0.10666 x 79.5 = 8.48g of CuO
You can do the same for NO2 but multiply your original moles (0.106666) by 2 as the ratio is 2:4