Quick Moles Q

I'm having a total mental block and I can't see how to work out the answer to this question:

For which of the following substances will 0.125mol of oxygen be enough for complete combustion?

1. 0.21mol of magnesium
2. 0.19 mol of aluminium
3. 0.12 mol of carbon
4. 0.075 mol of methane

Reply 1

charco

Study Forum Helper

write out the equation for the reaction for each then look at the moles equivalents

Reply 2

BCHL85

Write the equations to see how it works
1) Mg + 1/2O2 = MgO
-> need 0.21/2 mol of Oxygen -> enough.
2) 2Al + 3/2O2 = Al2O3
-> need (3/2)*(0.19/2) mole of oxygen -> not enough
3) C + O2 = CO2
-> enough
4) CH4 + 2O2 = CO2 + 2H2O
-> need 0.075*2 = 0.15 mole of oxygen -> not enough