How does diluting a 0.1 M solution of lactic acid, H\(C_3H_6O_3\), change its pH and percentage ionisation?
A - VCE - SSCE Chemistry - Question 20 - 2016 - Paper 1
Question 20
How does diluting a 0.1 M solution of lactic acid, H\(C_3H_6O_3\), change its pH and percentage ionisation?
A.
increase
decrease
B.
increase
increase
C.
decr... show full transcript
Worked Solution & Example Answer:How does diluting a 0.1 M solution of lactic acid, H\(C_3H_6O_3\), change its pH and percentage ionisation?
A - VCE - SSCE Chemistry - Question 20 - 2016 - Paper 1
Step 1
pH
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Answer
When diluting a solution of lactic acid, the concentration of lactic acid decreases. Since lactic acid is a weak acid, this results in an increase in pH as the solution becomes less acidic.
Step 2
Percentage ionisation
99%
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Answer
As the concentration of the acid decreases due to dilution, the percentage of lactic acid that ionises increases. This is because the equilibrium shifts towards the products in a dissociation reaction when the concentration of reactants is lowered, leading to a higher percentage ionisation.
