Q. 7.80 - An Introduction to General, Organic, and Biological Chemistry

Question

Using the models of the molecules (black = C, white = H, yellow = S, red = O), determine each of the following for models of compounds $1 and 2$:

(a). Molecular formula.

(b). Molar mass.

(c). No. of moles in $10 g$.

Step-by-Step Solution

Answer

(a) Molecular formula of given compounds are $S{O}_3 and C_{10}{H}_8$

(b) Molar mass of given compounds are $80 and 128$

(c) No of moles of given compounds are $0.125 and 0.078$

Part (a) Step 1: Given Information

We need to find the molecular formula of given molecules. 

Part (a) Step 2: Explanation

If we see the figures then we simply identify that 

Molecular formula of  $\left(1\right)$is $S{O}_3$

Molecular formula of  $\left(2\right)$ is $C_{10}{H}_8$

Part (b) Step 1: Given Information

We need to find the molar mass of given molecules.

Part (b) Step 2: Explanation

We know that the formula of 

1. $S{O}_3$
   
2. $C_{10}{H}_8$
   

So the molar mass are $m_1$and $m_2$:                                                                    

$$\begin{gathered} {\mathrm{m}}_1 = 32+16\times 3 \\ {\mathrm{m}}_1 = 80 \mathrm{amu} \\ {\mathrm{m}}_2 = 12\times 10+8 \\ {\mathrm{m}}_2 =128 \mathrm{amu} \end{gathered}$$

Part (c) Step 1: Given Information

We need to find no of moles present in$10 g$.

Part (c) Step 2: Explanation

We are know that $m_{1 }=80 ,m_2 = 128$

So let there are $n_1$and $n_2$moles are present in $10g$:

$$\begin{gathered} \mathrm{moles} = \frac{\mathrm{weight} \mathrm{in} \mathrm{g}}{\mathrm{molar} \mathrm{mass}} \\ {\mathrm{n}}_1 = \frac{10 \mathrm{g}}{80 \mathrm{amu}} \\ {\mathrm{n}}_1 = 0.125 \mathrm{mole} \\ {\mathrm{n}}_2 = \frac{10 \mathrm{g}}{128 \mathrm{amu}} \\ {\mathrm{n}}_2 = 0.078 \mathrm{mole} \end{gathered}$$