If 5.0 g of salt is dissolved in 100 mL of water, what is the concentration in g/L?

• A. 50 g/L
• B. 0.5 g/L
• C. 500 g/L
• D. 5 g/L

Answer: (A)

Concentration in g/L is mass of solute per liter of solution. Here, 5.0 g of salt is in 100 mL of solution. Convert volume to liters: 100 mL = 0.100 L. Then 5.0 g ÷ 0.100 L = 50 g/L. So the solution's concentration is 50 g per liter. (A quick reminder: small amounts like this often assume the volume change from dissolving is negligible.)