chem ques

乖学生

On heating, 0.02 mol of the element M reacts with 0.025 mol of oxygen gas. What is the empirical formula of the oxide of M?
A. M2O           B.MO2             C. M2O5             D. MO5

四月一日的小皮

let assume the equation should be

M(s) + O2 (g) --> MxOy(s) ---->(havent balance)

0.025 mol of O2 react with 0.02 mol of M
then, 1 mol of M react with how many mole of O2?
mole of O2 will b (1/0.02)x0.025 = 1.25mol
since we don't put mole in fraction form.
so,4 mole of M will react with (4x1.25)=5 mole of O2
So,putting into equation:
4M(s) + 5O2(g) --> MxOy (s)
balancing the equation will b the key to solve the problem.
in left hand side, M=4, O=10
so,on right hand side, x=4,y=10; OR x=2,y=5 (since we can balancing the equation by putting 2 at the oxide of M.)
So,what's the answer?
4M(s) + 5O2(g) --> 2M2O5 (s)