Concentration chemistry

Question

Explain the steps you would follow to make 500 mL of a 0.3 M solution of sucrose

(C ₁₂H₂₂O₁₁) in the lab.

Answer 1

Calculations

The molar mass of sucrose is 342.3 g / mol

0.3 M means 0.3 mols sucrose in 1 liter of solution.

Since you want to make 500 ml, which is equal to 0.5 liters, we need only 0.15 mols of sucrose

0.3 mols / L x 0.5 L = 0.15 mols

Converting this to grams of sucrose, we have ...

0.15 mols sucrose x 342.3 g / mol = 51.35 g sucrose needed = 50 g sucrose (1 sig. fig. based on 0.3 M)

Procedure

Weigh out 50 g sucrose

Transfer to a 500 ml volumetric flask

Add d. H2O to the final volume of 500 mls