Question

Elemental S reacts with O2 to form SO3 according to the reaction

2S+3O2→2SO3

Part A:
How many O2 molecules are needed to react with 8.03 g of S?

Express your answer numerically in units of molecules

Part B:

What is the theoretical yield of SO3 produced by the quantities described in Part A?

Express your answer numerically in grams.

Answer 1

A)

Molar mass of S = 32.07 g/mol

mass of S = 8.03 g

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

= 8.03/32.07

= 0.2504 mol

According to balanced equation

mol of O2 reacted = (3/2)* moles of S

= (3/2)*0.2504

= 0.3756 mol

use:

number of molecules = number of mol * Avogadro’s number

number of molecules = 0.3756 * 6.022*10^23 molecules

number of molecules = 2.262*10^23 molecules

Answer: 2.26*10^23 molecules

B)

Molar mass of S = 32.07 g/mol

mass of S = 8.03 g

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

= 8.03/32.07

= 0.2504 mol

According to balanced equation

mol of SO3 formed = moles of S

= 0.2504 mol

Molar mass of SO3,

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

= 1*32.07 + 3*16.0

= 80.07 g/mol

mass of SO3 = number of mol * molar mass

= 0.2504*80.07

= 20.05 g

Answer: 20.0 g