Question

What mass of sodium chloride is needed to prepare 200 ml of a 0.1 M solution

A. 0.232 grams
B. 292 grams
C. 1.17 grams
D. 117 grams

Answer 1

The right choice is (C) 1.17 grams

Step-by-step explanation:

As we know

c = n/V

n = c * V

n = m/M

m = c* V * M

m = 0.1mol/L * 0.2 L * 58.44 g/mol

m = 1.1688 g ≈ 1.17 g

So the mass of NaCl needed will be 1.17 grams

Answer 2

C. 1.17 grams

Step-by-step explanation:

• The molarity is the no. of moles of solute in a 1.0 L of the solution.

M = (mass/molar mass)solute x (1000/ V)

M = 0.1 M, mass = ??? g, molar mass of NaCl = 58.44 g/mol, V = 200.0 mL.

∴ mass of NaCl = (M)(molar mass)(V)/1000 = (0.1 M)(58.44 g/mol)(200.0 mL)/1000 = 1.168 g ≅ 1.17 g.