Question

The water company in Lexington, KY reported sodium levels of 16 ppm sodium. How many moles of sodium will be in 500.0 mL of water? (Assume a density of 1 g/mL)(MM Na: 23 g/mol)

a) 0.348 moles
b) 0.696 moles
c) 1.392 moles
d) 2.784 moles

Answer 1

To calculate the moles of sodium in the water, you can use the formula: moles =
`\frac{\text{mass}}{\text{molar mass}}` . The moles of sodium will be in 500.0 mL of water is 0.348 moles. Therefore, the correct answer is a) 0.348 moles.

Step-by-step explanation:

To calculate the moles of sodium in the water, you can use the formula:

moles =
`\frac{\text{mass}}{\text{molar mass}}`

Given that the density of water is 1 g/mL, the mass of sodium in 500.0 mL of water is 16 ppm × 500.0 mL. We then convert this mass to moles using the molar mass of sodium.

Mass of sodium =
`16 \, \text{ppm} * 500.0 \, \text{mL} * \frac{1 \, \text{g}}{1 \, \text{mL}}`

Moles of sodium =
`\frac{\text{Mass of sodium}}{\text{Molar mass of sodium}}`

Now, plug in the values:

Moles of sodium =
`\frac{16 \, \text{ppm} * 500.0 \, \text{mL} * \frac{1 \, \text{g}}{1 \, \text{mL}}}{23 \, \text{g/mol}}`

Calculate this expression to find the moles of sodium.

Moles of sodium ≈
`(16 * 500)/(23)` mol

Moles of sodium ≈ 0.348 moles

Therefore, the correct answer is a) 0.348 moles.