Answer:
see explanation
Explanation:
Solutions are prepared from one of three solute sources ...
- solid solute from manufacturer,
-liquid solute from manufacturer,
-stock concentrate of solute for dilution to lower concentrations.
In this problem, sucrose is a stock solid with a formula mass of 342.3 grams/mol. The amount of solid needed can be determined using the formula:
mass of solute needed (grams) = (Molarity needed x Volume needed in Liters x formula weight) / (decimal fraction purity of stock solid)
Molarity needed = 0.3M
Volume needed = 500 ml = 0.500 liters
Formula weight = 342.3 grams/mole
Purity factor (assumed) = 100% = 1.00 (should be posted on stock bottle label) For example, a 95% pure stock solid => purity factor of 0.95.
∴ grams of sucrose needed = (0.3M*)(0.500L)(342.3g/mole)/(1.00) =51.345 grams sucrose.
Measure 51.345 grams of sucrose into mixing vessel and add solvent water up to, but not to exceed 500 ml total volume. Mix until homogeneous.
