Question

The densities of crystalline co2 and nh3 at 160 k are 1.56 and 0.84 g/cm3, respectively. calculate their molar volumes.

Answer 1

Answer: The molar volume of carbon dioxide is
`28.21cm^3` and that of ammonia is
`20.275cm^3`

Step-by-step explanation:

To calculate the molar volume for the given densities, we use the mass to be molar mass.

To calculate volume of a substance, we use the equation:

`\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}` ......(1)

• For carbon dioxide:

Density of carbon dioxide =
`1.56g/cm^3`

Molar mass of carbon dioxide = 44.01 g

Putting values in equation 1, we get:

`1.56g/cm^3=\frac{44.01g}{\text{Volume of carbon dioxide}}\\\\\text{Volume of carbon dioxide}=28.21cm^3`

Hence, the molar volume of carbon dioxide is
`28.21cm^3`

• For ammonia:

Density of ammonia =
`0.84g/cm^3`

Molar mass of ammonia = 17.031 g

Putting values in equation 1, we get:

`0.84g/cm^3=\frac{17.031g}{\text{Volume of ammonia}}\\\\\text{Volume of ammonia}=20.275cm^3`

Hence, the molar volume of ammonia is
`20.275cm^3`

Answer 2

The molar volume, symbol Vm, is the volume occupied by one mole of a substance at a given temperature and pressure. It is equal to the molar mass divided by the mass density. Therefore, we calculate as follows:

Vm(CO2) = 44.01 / 1.56 = 28.21 cm^3 / mol
Vm(NH3) = 17.03 / 0.84 = 20.27 cm^3 / mol