Q. 7.11 - An Introduction to General, Organic, and Biological Chemistry

Question

Calculate the molar mass for each of the following : 

a. ${\mathrm{Cl}}_2$      b. ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_3$     c. ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$

Step-by-Step Solution

Answer

a. The molar mass of ${\mathrm{Cl}}_2$ is $70.90 \mathrm{g}$

b. The molar mass of ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_3$ is $90.00 \mathrm{g}$

c. The molar mass of ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$ is $262.76 \mathrm{g}$

Part (a) Step 1 : Given information

We have to calculate the molar mass of ${\mathrm{Cl}}_2$.

Part (a) Step 2 : Simplification

We know that,

Molar mass of one $\mathrm{Cl}$ atom = $35.45 \mathrm{g}$

So, molar mass of ${\mathrm{Cl}}_2$( two $\mathrm{Cl}$ atoms ) = $2\times \left(35.45\right)$=$70.90 \mathrm{g}$

Part (b) Step 1 : Given information

We have to calculate the molar mass of  ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_3$.

Part (b) Step 2 : Simplification

We know that,

The molar mass of one $\mathrm{C}$ atom = $12.01 \mathrm{g}$

The molar mass of one $\mathrm{H}$ atom = $1.00 \mathrm{g}$

The molar mass of one $\mathrm{O}$ atom = $15.99 \mathrm{g}$

So, the molar mass of ${\mathrm{C}}_3{\mathrm{H}}_6{\mathrm{O}}_3$ = $3\left(12.01\right) + 6\left(1.00\right) + 3\left(15.99\right)$ = $90 \mathrm{g}$

Part (c) Step 1 : Given information

We have to calculate the molar mass of  ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$.

Part (c) Step 2 : Simplification

We know that,

The molar mass of one $\mathrm{Mg}$ atom = $24.30 \mathrm{g}$

The molar mass of one $\mathrm{P}$ atom = $30.97 \mathrm{g}$

The molar mass of one $\mathrm{O}$ atom = $15.99 \mathrm{g}$

So, the molar mass of ${\mathrm{Mg}}_3{\left({\mathrm{PO}}_4\right)}_2$ = $3\left(24.30\right) + 2\left(30.97\right) + 8\left(15.99\right)$ = $262.76 \mathrm{g}$