Questions: How many molecules of ammonia are present in 3.0 g of ammonia (Formula = NH3)? 1.1 x 10^23 1.8 x 10^1 3.6 x 10^23 1.2 x 10^24 2.9 x 10^-25

Transcript text: 6. How many molecules of ammonia are present in 3.0 g of ammonia (Formula $=\mathrm{NH}_{3}$ )? $1.1 \times 10^{23}$ $1.8 \times 10^{1}$ $3.6 \times 10^{23}$ $1.2 \times 10^{24}$ $2.9 \times 10^{-25}$

Solution

Solution Steps

Step 1: Calculate the Molar Mass of Ammonia

The chemical formula for ammonia is $\mathrm{NH}_3$. To find the molar mass, we sum the atomic masses of nitrogen and hydrogen:

Nitrogen (N): $14.01 \, \text{g/mol}$
Hydrogen (H): $1.008 \, \text{g/mol}$

The molar mass of $\mathrm{NH}_3$ is: \[ 14.01 + 3 \times 1.008 = 17.034 \, \text{g/mol} \]

Step 2: Calculate the Number of Moles of Ammonia

To find the number of moles in 3.0 g of ammonia, use the formula: \[ \text{moles of } \mathrm{NH}_3 = \frac{\text{mass}}{\text{molar mass}} = \frac{3.0 \, \text{g}}{17.034 \, \text{g/mol}} \]

Calculating this gives: \[ \text{moles of } \mathrm{NH}_3 = 0.1761 \, \text{mol} \]

Step 3: Calculate the Number of Molecules

Using Avogadro's number ($6.022 \times 10^{23} \, \text{molecules/mol}$), calculate the number of molecules: \[ \text{molecules of } \mathrm{NH}_3 = 0.1761 \, \text{mol} \times 6.022 \times 10^{23} \, \text{molecules/mol} \]

Calculating this gives: \[ \text{molecules of } \mathrm{NH}_3 = 1.060 \times 10^{23} \]