Question

1) According to the following reaction, how many grams of water are needed to form 22.2 grams of oxygen gas? water (l) hydrogen (g) + oxygen (g) _____ grams water

Answer 1

The chemical reaction to the transformation is

2H2O---> 2H2+O2

for every two moles of H2, one mole of O2 will be formed. The stoichiometric ratio for the formation of O2 will be 1/2, with respect to water which is the limiting reagents.

molar mass of H2O = 18 g

molar mass of O2 = 32 g

moles of H2O used = 22.2/18 moles = 1.23 moles

The number of moles of O2 formed = 1.23/2 =0.616 moles

grams of O2 formed will be determined by using formula

number of moles formed = grams of O2 formed / Molar mass

so , Mass of O2 formed = 0.616*32 = 19.712 g