Question

Calculate the molarity of a solution that has 18.0 g of glucose, C6H12O6, dissolved in 80.0 g of water.

Answer 1

1.25 M

Step-by-step explanation:

In this case, the solute is C₆H₁₂O₆ and the solvent is H₂O.To find the molarity, you need to (1) convert the mass C₆H₁₂O₆ to moles (via molar mass), then (2) convert grams H₂O to liters H₂O, and then (3) calculate the molarity.

(Step 1)

Molar Mass (C₆H₁₂O₆): 6(12.011 g/mol) + 12(1.008 g/mol) + 6(15.998 g/mol)

Molar Mass (C₆H₁₂O₆): 180.15 g/mol

18.0 g C₆H₁₂O₆ 1 mole
------------------------ x ----------------- = 0.0999 moles C₆H₁₂O₆
180.15 g

(Step 2)

1,000 grams = 1 L

80.0 g H₂O 1 L
-------------------- x ------------------- = 0.0800 L H₂O
1,000 g

(Step 3)

Molarity = moles solute / volume solvent (L)

Molarity = 0.0999 moles / 0.0800 L

Molarity = 1.25 M