Question

Calculate the molarity of a solution containing 20.7 g of potassium carbonate dissolved in 500 mL of solution (assume density of solution = 1 g mL${}^{-1}$).

• A. 0.113 M
  
• B. 0.213 M
  
• C. 0.300 M
  
• D. 0.413 M
  

Answer 1

Answer: (C)

0.300 M

molar mass of $K_{2}C{O}_3$ = 138

moles of $K_{2}C{O}_3=\frac{20.7}{138}$ $=0.15$ moles

Molarity = $\frac{No.ofmoles}{Volume}\times 1000$$=\frac{0.15}{500}\times 1000$$=0.30M$