Question

What is the mass of H2O produced when 10.0 grams of H2 reacts completely with 80.0 grams of O2?

A(70.0 grams)
B(90.0 grams)
C(180.0 grams)
C(800.0 grams)

Answer 1

H₂:

M=2g/mol
m=10g

n = m/M = 10g/2g/mol = 5mol

O₂:

M = 32g/mol
m = 80g

n = m/M = 80g/32g/mol = 2,5mol

2H₂ + O₂ ⇒ 2H₂O
2mol : 1mol : 2mol
5mol : 2,5mol : 5mol
10g : 80g : 10g+80g=90g

B