Problem: What is the pH of a solution in which 0.250 mol of NH3 (Kb = 1.8 × 10-5) is dissolved in sufficient water to make 1.00 L of solution?a. 2.67b. 11.33c. 4.93d. 13.4e. 9.07

FREE Expert Solution

We are being asked to calculate the pH for a 0.250 mol NH3 in 1 L solution

NH3 is a neutral amine, therefore we know that it is a weak base.

NH3(aq) + H2O(aq)  OH(aq) + NH4+(aq)Kb = 1.8 × 10-5


Calculate the molarity:

Molarity = moles soluteL solutionMolarity = 0.250 mol1 L

Molarity =  0.250 M


From this, we can construct an ICE table. Remember that liquids are ignored in the ICE table.




The Kb expression for NH3 is:


Kb = productsreactants = [OH-][NH4+][NH3]


Note that each concentration is raised by the stoichiometric coefficient: [NH3], [OH] and [NH4+] are raised to 1.


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Problem Details

What is the pH of a solution in which 0.250 mol of NH3 (Kb = 1.8 × 10-5) is dissolved in sufficient water to make 1.00 L of solution?

a. 2.67

b. 11.33

c. 4.93

d. 13.4

e. 9.07

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Weak Bases concept. If you need more Weak Bases practice, you can also practice Weak Bases practice problems.