Question

What is the molarity (M) of the following solutions?

a. 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution

b. A 2.6 L solution made with 235.9 g of KBr​

Answer 1

The molarity (M) of the following solutions are :

A. M = 0.88 M

B. M = 0.76 M

Step-by-step explanation:

A. Molarity (M) of 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution.

Molar mass of Al(OH)3 = Mass of Al + 3(mass of O + mass of H)

= 27 + 3(16 + 1)

= 27 + 3(17) = 27 + 51

= 78 g/mole

`Al(OH)_3` = 78 g/mole

Given mass= 19.2 g/mole

`Mole = (Given\ mass)/(Molar\ mass)`

`Mole = (19.2)/(78)`

Moles = 0.246

`Molarity = (Moles\ of\ solute)/(Volume\ of\ solution(L))`

Volume = 280 mL = 0.280 L

`Molarity = (0.246)/(0.280))`

Molarity = 0.879 M

Molarity = 0.88 M

B .The molarity (M) of a 2.6 L solution made with 235.9 g of KBr​

Molar mass of KBr = 119 g/mole

Given mass = 235.9 g

`Mole = (235.9)/(119)`

Moles = 1.98

Volume = 2.6 L

`Molarity = (Moles\ of\ solute)/(Volume\ of\ solution(L))`

`Molarity = (1.98)/(2.6))`

Molarity = 0.762 M

Molarity = 0.76 M