Question

What is the mass of 9.50 x 1022 molecules of NH3?

Answer 1

The mass of NH3 is 2.682 grams

Explanation

Given data

The number of NH3 molecules = 9.50 x 10^22 molecules

Let x represents the mass of NH3

Firstly, we need to find the number of moles of NH3 using the below formula

`\text{Number of moles = }\frac{no\text{ of particles}}{\text{Avogadro's constant}}`

Recall that, Avogadro's constant = 6.02 x 10^23

`\begin{gathered} \text{ number of moles = }(9.50\cdot10^(22))/(6.02\cdot10^(23)) \\ \text{Number of moles = }(9.50)/(6.02)\cdot10^{22\text{ - 23}} \\ \text{Number of moles = 1.578 }\cdot10^(-1) \\ \text{Number of moles =0.158 mole} \end{gathered}`

From the above calculation, you will see that the number of moles of NH3 is 0.158 mole

The next process is to find the mass of NH3 using the below formula

`\text{mole = }\frac{\text{ reacting mass}}{\text{ molar mass}}`

According to the periodic table, the molar mass of NH3 = 17 g/mol

`\begin{gathered} 0.158\text{ = }\frac{\text{ x}}{17} \\ \text{Cross multiply} \\ x\text{ = 0.158 }\cdot\text{ 17} \\ x\text{ = 2.682 grams} \end{gathered}`

Therefore, the mass of NH3 is 2.682 grams