Question

18) Calculate the molarity

of a solution if 42 grams
of NaCl is dissolved in
780 mL of water.
a .56 M
b 92 M
c 1.1 M
d 54M

Answer 1

B. 0.92 M

Step-by-step explanation:

Molarity of a solution = number of moles (n) ÷ volume (V)

According to the information provided in this question;

mass of NaCl = 42g

Volume of water = 780mL

Using mole = mass/molar mass

Molar mass of NaCl = 23 + 35.5 = 58.5g/mol

mole = 42/58.5

mole (n) = 0.72mol

Volume (V) = 780 mL = 780/1000 = 0.780 L

Hence, molarity = n/V

Molarity = 0.72/0.780

Molarity = 0.923 M