Ammonia gas is passed into water, yielding a solution of density `0.93 g//cm^(3)` and containing `18.6% NH_(3)` by weight. The mass of NH3 per cc of the solution is :

Options

A. 0.17 g / `cm^(3)`
B. 0.34 g / `cm^(3)`
C. 0.51 g / `cm^(3)`
D. 0.68 g / `cm^(3)`

Answer

To find the mass of NH3 per cc of the solution, we can follow these steps:

### Step 1: Understand the Given Information
We are given:
- Density of the solution = 0.93 g/cm³
- Percentage of NH3 by weight = 18.6%

### Step 2: Calculate the Mass of NH3 in 100 g of Solution
Since the percentage by weight is given, we can calculate the mass of NH3 in 100 g of the solution:
\[ \text{Mass of NH3} = \frac{18.6}{100} \times 100 \text{ g} = 18.6 \text{ g} \]

### Step 3: Calculate the Volume of 100 g of Solution
Using the density formula, we can find the volume of 100 g of the solution:
\[ \text{Density} = \frac{\text{Mass}}{\text{Volume}} \implies \text{Volume} = \frac{\text{Mass}}{\text{Density}} = \frac{100 \text{ g}}{0.93 \text{ g/cm}^3} \approx 107.53 \text{ cm}^3 \]

### Step 4: Calculate the Mass of NH3 per cc of the Solution
Now, we can find the mass of NH3 per cc of the solution:
\[ \text{Mass of NH3 per cc} = \frac{\text{Mass of NH3}}{\text{Volume of solution}} = \frac{18.6 \text{ g}}{107.53 \text{ cm}^3} \approx 0.173 \text{ g/cm}^3 \]

### Step 5: Round to the Appropriate Significant Figures
Rounding 0.173 g/cm³ to two decimal places gives us:
\[ \text{Mass of NH3 per cc} \approx 0.17 \text{ g/cm}^3 \]

### Final Answer
Thus, the mass of NH3 per cc of the solution is approximately **0.17 g/cm³**.

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