Question

the equation representing the chemical change used to produce W is shown below. what mass of W is produced from 2.0g H2 and 50g of WO3?

WO3 + 3H2 ---> W + 3 H2O

Answer 1

Molar mass of WO3,

MM = 1*MM(W) + 3*MM(O)

= 1*183.8 + 3*16.0

= 231.8 g/mol

mass(WO3)= 50.0 g

number of mol of WO3,

n = mass of WO3/molar mass of WO3

=(50.0 g)/(231.8 g/mol)

= 0.2157 mol

Molar mass of H2 = 2.016 g/mol

mass(H2)= 2.0 g

number of mol of H2,

n = mass of H2/molar mass of H2

=(2.0 g)/(2.016 g/mol)

= 0.9921 mol

Balanced chemical equation is:

WO3 + 3 H2 ---> W + 3 H2O

1 mol of WO3 reacts with 3 mol of H2

for 0.2157 mol of WO3, 0.6471 mol of H2 is required

But we have 0.9921 mol of H2

so, WO3 is limiting reagent

we will use WO3 in further calculation

Molar mass of W = 183.8 g/mol

According to balanced equation

mol of W formed = (1/1)* moles of WO3

= (1/1)*0.2157

= 0.2157 mol

mass of W = number of mol * molar mass

= 0.2157*1.838*10^2

= 39.7 g

Answer: 39.7 g