Question

Ammonia, NH3, is a weak base that is often used in household cleaning solutions. what is the pH of a solution of ammonia that contains 5.0 g of ammonia in 709 mL

Answer 1

11.44

Step-by-step explanation:

`K_b` = Base ionization constant of ammonia =
`1.8* 10^(-5)`

m = Mass of ammonia = 5 g

V = Volume of ammonia = 709 mL =
`709* 10^(-3)\ \text{L}`

M = Molar mass of ammonia = 17.03 g/mol

Molaritiy of ammonia

`C=(n)/(V)\\\Rightarrow C=((m)/(M))/(V)\\\Rightarrow C=((5)/(17.03))/(709* 10^(-3))\\\Rightarrow C=0.414`

We have the relation

`pOH=(1)/(2)(pK_b-\log C)\\\Rightarrow pOH=(1)/(2)(-\log (1.8* 10^(-5))-\log 0.414)\\\Rightarrow pOH=2.56`

`pH+pOH=14\\\Rightarrow pH=14-pOH\\\Rightarrow pH=14-2.56\\\Rightarrow pH=11.44`

The pH of the solution is 11.44.