We’re being asked to calculate the pH of a solution 0.201 mol NH4CN and enough water to make 1.00 L of solution.
NH4CN dissociates in water in the following manner:
NH4CN(s) ⇌ NH4+ (aq) + CN- (aq)
NH4+ is the conjugate acid of a weak base, NH3:
NH3 + H2O ⇌ NH4+ + OH-; Kb=1.76x10-5
CN- is the conjugate base of a weak acid, HCN:
HCN + H2O ⇌ CN- + H3O+ ; Ka= 4.9x10-10
The pH of the salt of a weak acid and a weak base can be calculated using the following equation:
We will do the following steps to solve this problem:
Step 1: Calculate pKa of the weak acid
Step 2: Calculate the pKb of the weak base
Step 3: Determine pKw
Step 4: Calculate the pH of the salt
Calculate the pH of a solution prepared from 0.201 mol of NH4CN and enough water to make 1.00 L of solution.
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 Acids concept. If you need more Weak Acids practice, you can also practice Weak Acids practice problems.
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Based on our data, we think this problem is relevant for Professor Vasquez's class at OKSTATE.