Question

1. which of the following compounds has a molar mass of 44.0 g/mol

a) co2
b) h2o
c) nacl
d) o2

Explanation:

Step1: Get atomic masses (periodic table)

Atomic masses: $C=12.0\ \text{g/mol}$, $O=16.0\ \text{g/mol}$, $H=1.0\ \text{g/mol}$, $Na=23.0\ \text{g/mol}$, $Cl=35.5\ \text{g/mol}$

Step2: Calculate molar mass of a) $\text{CO}_2$

$M(\text{CO}_2) = 12.0 + 2\times16.0 = 44.0\ \text{g/mol}$

Step3: Calculate molar mass of b) $\text{H}_2\text{O}$

$M(\text{H}_2\text{O}) = 2\times1.0 + 16.0 = 18.0\ \text{g/mol}$

Step4: Calculate molar mass of c) $\text{NaCl}$

$M(\text{NaCl}) = 23.0 + 35.5 = 58.5\ \text{g/mol}$

Step5: Calculate molar mass of d) $\text{O}_2$

$M(\text{O}_2) = 2\times16.0 = 32.0\ \text{g/mol}$

Answer:

a) CO2