Question

What is the concentration of ammonia in a solution made by dissolving 3.75 g of ammonia in 120.0 l of water?

Answer 1

Below are the choices that can be found elsewhere:

a) 7.05 M 
b) 3.78×10^−2 M 
c)1.84×10^−3 M 
d)0.0313 M 
e)1.84 M

Below is the answer:

mol = mass/m.wt = 3.75/17.03 = 0.22 mol 
Molarity = mol / Volume(L) = 0.22/120.0 = 1.84 * 10^-3 
c)1.84×10^−3 M

Answer 2

Answer: The concentration of ammonia is 0.00184 M

Explanation:

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}}{\text{Molar mass of solute}\times \text{Volume of solution (in L)}}$

We are given:

Mass of solute (ammonia) = 3.75 g

Molar mass of ammonia = 17 g/mol

Volume of solution = 120.0 L

Putting values in above equation, we get:

$\text{Concentration of ammonia}=\frac{3.75g}{17g/mol\times 120.0L}\\\\\text{Concentration of ammonia}=0.00184M$

Hence, the concentration of ammonia is 0.00184 M