I have done some more questions but these are about what mass is needed, not what mass is formed. I think I have done them correct, can you check whether my answers are okay please? I'd appreciate it very much.
What mass of oxygen is needed to react with 8.5g of hydrogen sulphide?
2H2S+3O2->2SO2+2H2O
2 moles of hydrogen sulphide and 3 moles of oxygen, therefore the ratio is 2:3
8.5/34=0.25moles
(0.25/2)x3=0.375 (because of the ratio)
0.375x32=12g
What mass of hydrogen is needed to react with 32g of copper oxide?
CuO+H2->Cu+H2O
1 mole of copper oxide and 1 mole of hydrogen, therefore there is a 1:1 ratio
32/(63.5+16.0)=0.4moles
0.4x2=0.8g
What mass of oxygen reacts with 192g of magnesium?
2Mg+O2->2MgO
2 moles of magnesium and 1 mole of oxygen, therefore ratio is 2:1
192/(2x24.3)=3.9moles
3.9x32=124.8g
Do I still have to divide 3.9 by 2 because of the ratio?
What mass of carbon monoxide is needed to react with 1kg of iron oxide?
Fe2O3+3CO->2Fe+3CO2
1 mole of iron oxide and 3 moles of oxygen, therefore the ratio is 1:3
1000/((2x55.8)+(48))=6.27moles
6.27x(3x(12+16))=526.68g
What mass of oxygen is needed to react with 184g of sodium?
4Na+O2->2Na2O
4 moles of sodium and 1 mole of oxygen, therefore the ratio is 4:1
184/(4x23)=2
2/4=0.5
0.5x32=16g
What mass of oxygen is needed to react with 4.5g of ethane?
2C2H6+7O2->4CO2+6H2O
2 moles of C2H6 and 7 moles of oxygen, therefore the ratio is 2:7
4.5/2x((12x2)+(2x6))=0.0625moles
(0.0625/2)x7=0.21875
0.21875x32=7g
Please can you check that my working is correct and if not, tell me where I am going wrong.
Thanks in advance.