Question

The molarity of solution containing 2.8% mass volume solution of KOH is
(1)M/10
(2)M/2
(3)M/5
(4)1M

Answer 1

Question #49296, Chemistry, Physical Chemistry

The molarity of solution containing 2.8% mass volume solution of KOH is

(1) M/10

(2) M/2

(3) M/5

(4) 1M

Answer:

M(KOH) = 56 g/ml

w = $\frac{m_{\text{KOH}}}{m_{\text{solution}}}$ 100% = 2.8%

c-?

c = n/V

n = m/M

assume that the density of the solution approximately equal to the density of water: ρ = 1 g/mL.

Suppose, that m_solution = 100 g then

m_KOH = w · m_solution / 100% = 2.8 * 100 / 100% = 2.8 g

n_KOH = 2.8 / 56 = 0.05 mol

c = 0.05 mol / 0.1 L = 0.5 mol/L = M/5

Answer: (3) M/5

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