Question

A sample of $90.0$ g of glucose is dissolved in enough water to yield $200$ millilitres of solution. What is the molar concentration of glucose ?

(Molecular weight $=180$ g/mole)

• A. $0.500M$
• B. $1.00M$
• C. $2.00M$
• D. $2.50M$
• E. $10.0M$

Answer 1

Answer: (D)

$2.50M$

Molarity is defined as moles of solute per liter of solution.

$\text{Molarity}=\frac{\text{moles of solute}}{\text{volume of solution (in L)}}=\frac{\text{mass of solute}}{\text{molecular weight of solute}\times \text{volume of solution (in L)}}$

The volume of solution is 200 ml or 0.200 L.
$\text{Molarity}=\frac{90.0g}{180g/mol\times 0.200L}=2.50$ $M$.