Problem: Find the pH of each of the following solutions of mixtures of acids.5.5×10−2 M in acetic acid and 5.5×10−2 M in hydrocyanic acid

FREE Expert Solution

We’re being asked to calculate the pH of a mixture of weak acids containing 5.5×10−2 M in acetic acid and 5.5×10−2 M in hydrocyanic acid.


Remember that weak acids partially dissociate in water and that acids donate H+ to the base (water in this case). 


The dissociation of each weak acid is as follows:


  • HC2H3O2(aq) + H2O(l)  H3O+(aq) + C2H3O2(aq)
  • HCN(aq) + H2O(l)  H3O+(aq) + CN(aq)

**chemical formula of each weak acid can be found in textbooks/online


To solve for the pH of the mixture, we need to do these steps:


Step 1. Determine the weak acid with a higher acid dissociation constant, K

Step 2. Construct an ICE table for each weak acid to solve for the concentration of H3Ofrom each weak acid

Step 3. Solve for the pH of the mixture


Recall that pH is given by:


pH=-log[H3O+]

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Problem Details

Find the pH of each of the following solutions of mixtures of acids.

5.5×10−2 M in acetic acid and 5.5×10−2 M in hydrocyanic acid