Question

Given that the molar mass of NaCl is 58.44 g/mol, Solve for the molarity of a solution that contains 87.75 g of NaCl in 500 mL of solution.

A.) 0.333 M
B.) 0.751 M
C.) 1.50 M
D.) 3.00 M

Answer 1

Most of the information's required for solving this question is already given. Let us now focus on the problem in hand.

Grams/Molar Mass = Moles 

Molarity = Moles/Liters

The above formulas are important for solving this problem.

Number of moles of Nacl = 87.75/58.44

                                         = 1.50

Molarity = Number of moles of solute (here NaCl) / Volume of solution in Liters

Then

Volume of solution in Liters = Number of moles of solute (here NaCl)/Molarity

Volume of solution in Liters = 500/1500

                                            = 0.333 M

The correct option among all the options that are given in the question is the first option or option "A".

Answer 2

Molarity is defined as the number of moles of solute per 1 L of solvent.

the mass of NaCl in the solution is 87.75 g

number of moles of NaCl is calculated by dividing mass present by molar mass

number of NaCl moles = 87.75 g / 58.44 g/mol = 1.502 mol

the number of NaCl moles in 500 mL is - 1.502 mol

therefore number of NaCl moles in 1000 mL is - 1.502 mol/ 500 mL x 1000 mL/L = 3.004 mol

molarity of NaCl is - 3.004 M

answer is D. 3.00 M