Question

A student weighs out 8.21 g of (NH4)2S, transfers it to a 500. mL volumetric flask, adds enough water to dissolve the solid and then adds water to the 500 mL mark on the neck of the flask. Calculate the concentration (in molarity units) of ammonium sulfide in the resulting solution?

Answer 1

Answer: 0.24 M

Step-by-step explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

`Molarity=(n* 1000)/(V_s)`

where,

n= moles of solute

`Moles=\frac{\text{Given mass}}{\text{Molar mass}}=(8.21g)/(68.154g/mol)=0.12mole`

`V_s` = volume of solution in ml = 500 ml

Putting in the values:-

`Molarity=(0.12* 1000)/(500)=0.24M`

Thus the molarity of
`(NH_4)_2S` is 0.24 M.