Question

50mL of potassium hydroxide (KOH) solution contains 7 grams of potassium hydroxide.

What is the molarity (mol/L) of the potassium hydroxide solution?
Given the atomic masses:
K= 39,0 = 16 and H= 1​

Answer 1

2.5 mol/L

Step-by-step explanation:

We'll begin by calculating the number of mole in 7 g of KOH. This can be obtained as follow:

Mass of KOH = 7 g

Molar mass of KOH = 39 + 16 + 1

= 56 g/mol

Mole of KOH =?

Mole = mass /molar mass

Mole of KOH = 7 / 56

Mole of KOH = 0.125 mole

Next, we shall convert 50 mL to L. This can be obtained as follow:

1000 mL = 1 L

Therefore,

50 mL = 50 mL × 1 L / 1000 mL

50 mL = 0.05 L

Finally, we shall determine the molarity of the KOH solution. This can be obtained as follow:

Mole of KOH = 0.125 mole

Volume = 0.05 L

Molarity of KOH =?

Molarity = mole / Volume

Molarity of KOH = 0.125 / 0.05

Molarity of KOH = 2.5 mol/L

Thus, the molarity of the KOH solution is 2.5 mol/L