What is the concentration of [tex]\[ H_2(g) \][/tex], in parts per million, in a solution that contains [tex]\[ 0.0001 \, \text{g} \][/tex] of [tex]\[ H_2(g) \][/tex] dissolved in [tex]\[ 100. \, \text{g} \][/tex] of [tex]\[ H_2O(l) \][/tex]?

A. [tex]\[ 1 \, \text{ppm} \][/tex]

B. [tex]\[ 1.0 \times 10^2 \, \text{ppm} \][/tex]

C. [tex]\[ 10 \, \text{ppm} \][/tex]

D. [tex]\[ 1.0 \times 10^3 \, \text{ppm} \][/tex]



Answer :

To determine the concentration of [tex]\( H_2(g) \)[/tex] in parts per million (ppm) in a solution that contains [tex]\( 0.0001 \, \text{g} \)[/tex] of [tex]\( H_2(g) \)[/tex] dissolved in [tex]\( 100.0 \, \text{g} \)[/tex] of [tex]\( H_2O(l) \)[/tex], follow these steps:

1. Identify the masses involved:

- Mass of [tex]\( H_2(g) \)[/tex]: [tex]\( 0.0001 \, \text{g} \)[/tex]
- Mass of [tex]\( H_2O(l) \)[/tex]: [tex]\( 100.0 \, \text{g} \)[/tex]

2. Understand the definition of ppm:

Parts per million (ppm) is calculated as the mass of the solute divided by the mass of the solution, multiplied by [tex]\( 1{,}000{,}000 \)[/tex].

3. Set up the concentration formula:

[tex]\[ \text{Concentration (ppm)} = \left( \frac{\text{Mass of } H_2(g)}{\text{Mass of } H_2O(l)} \right) \times 1{,}000{,}000 \][/tex]

4. Plug in the given values:

[tex]\[ \text{Concentration (ppm)} = \left( \frac{0.0001 \, \text{g}}{100.0 \, \text{g}} \right) \times 1{,}000{,}000 \][/tex]

5. Carry out the division:

[tex]\[ \frac{0.0001 \, \text{g}}{100.0 \, \text{g}} = 1 \times 10^{-6} \][/tex]

6. Multiply by [tex]\( 1{,}000{,}000 \)[/tex] to convert to ppm:

[tex]\[ 1 \times 10^{-6} \times 1{,}000{,}000 = 1 \][/tex]

Therefore, the concentration of [tex]\( H_2(g) \)[/tex] in the solution is [tex]\( 1 \)[/tex] ppm.

The correct answer is:
A. [tex]\( 1 \, \text{ppm} \)[/tex]