Question

The tungsten metal used for filaments in light bulbs is made by reaction of tungsten(VI) oxide with hydrogen:
WO3(s)+3H2(g)→W(s)+3H2O(g)
The above reaction was performed and produced 5.78 g of tungsten.

(c) How many moles of hydrogen were required to produce the 5.78 g of tungsten?

(d) How many grams of tungsten(VI) oxide must you start with to prepare 5.78 g of tungsten? (For WO3, MW=231.8amu.)

(e) How many grams of hydrogen must you start with to prepare 5.78 g of tungsten?

Answer 1

C)

Molar mass of W = 183.8 g/mol

mass of W = 5.78 g

molar mass of W = 183.8 g/mol

mol of W = (mass)/(molar mass)

= 5.78/183.8

= 0.0314 mol

According to balanced equation

mol of H2 formed = (3/1)* moles of W

= (3/1)*0.0314

= 0.0943 mol

Answer: 0.0943 mol

d)

According to balanced equation

mol of WO3 formed = moles of W

= 0.0314 mol

mass of WO3 = number of mol * molar mass

= 0.0314*231.8

= 7.29 g

Answer: 7.29 g

e)

mass of H2 = number of mol * molar mass

= 0.0943*2.016

= 0.190 g

Answer: 0.190 g