Question

Calculate the mass and express your answer with the appropriate units.

A. 66.4 mmol SO3

B. 1.38 mol xenon dioxide

3. How many moles (of molecules or formula units) are in each sample?

131 kg CaO

Express your answer to three significant figures and include the appropriate units.

Answer 1

A.)

66.4 mmol SO3

Calculation of mass :

We know mass in g = moles x molar mass

Molar mass of SO3 = 80.063 g per mol

Lets convert mmol to mol

Mols of SO3 = 66.4 mmol x 1 mol / 1000 mmol

= 0.0664 mol

Mass of SO3 in g = 0.0664 mol x 80.063 g /mol

= 5.32 g

B).

1.38 mol Xenon dioxide

XeO2

Molar mass of XeO2 = 163.288 g/mol

Mass of 1.38 mol XeO2 = 1.38 mol x 163.288 g /mol

= 225. g

3).

Number of moles in 131 kg CaO

Conversion of moles mass to g

Mass of CaO in g = 131 kg x 1000 g / 1kg

= 131000 g CaO

Calculation of moles of CaO

= Mass in g / molar mass

Molar mass of CaO = 56.077 g /mol

Number of moles of CaO = 131000 g / 56.077 g per mol

= 2340

Number of moles of CaO = 2340 mol