Question

solve the stoichiometry problems. show your work and use significant figures. round atomic mass numbers to two decimal places.

1. what is the molar mass of $c_2h_6$?
2. what is the molar mass of $al_2(co_3)_3$?

Explanation:

Step1: List atomic masses (C, H)

Atomic mass of C = $12.01\ \text{g/mol}$, Atomic mass of H = $1.01\ \text{g/mol}$

Step2: Calculate molar mass of $\text{C}_2\text{H}_8$

$$2\times12.01 + 8\times1.01 = 24.02 + 8.08 = 32.10\ \text{g/mol}$$

Step3: List atomic masses (Al, C, O)

Atomic mass of Al = $26.98\ \text{g/mol}$, Atomic mass of C = $12.01\ \text{g/mol}$, Atomic mass of O = $16.00\ \text{g/mol}$

Step4: Calculate molar mass of $\text{Al}_2(\text{CO}_3)_3$

$$2\times26.98 + 3\times(12.01 + 3\times16.00) = 53.96 + 3\times(60.01) = 53.96 + 180.03 = 233.99\ \text{g/mol}$$

Answer:

1. $32.10\ \text{g/mol}$
2. $233.99\ \text{g/mol}$