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pH of Solutions: Strong Acids, pH of Solutions: Weak Acids, pH of solution/mixture are considered the most difficult concepts.
39 Questions around this concept.
Which one of the following statements is not true?
Among the following acids which has the lowest value?
When the hydrogen ion concentration changes by a factor of 1000 , the value of
of the solution
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The pH of 0.1 M aqueous solutions of NaCl, CH3COONa and NH4Cl will follow the order
The $p H_{\text {values of }}(i) 0.1 \mathrm{MHCl}_{a q}(i i) 0.1 \mathrm{MKOH},(i i i)_{\text {tomato juice and }}(i v)_{\text {pure water }}$ follow the order
pH is also referred to as potential or power of hydrogen. Mathematically, it can be represented as follows:
If solution is neutral, then:
Kw = [H3O+][OH-]
From the ionic product of water, we know:
Kw = 10-14
[H3O+] = [OH-] = x (since solution is neutral)
Thus, 10-14 = Kw = x2
x = 10-7
Now, [H3O+] = 10-7
Thus, pH = - log10(H3O+) = - log10(10-7) = 7
For Acidic solutions: For Basic solutions:
For acidic solutions, we must have [H3O+] > [OH-] For basic solutions, we must have [H3O+] < [OH-]
Thus, [H3O+] > 10-7 Thus, [H3O+] < 10-7
Thus, [H3O+] for acids can be 10-6, 10-5, 10-4, etc. Thus, [H3O+] for basics can be 10-8, 10-9, 10-10, etc.
Thus, pH of acids can be 6, 5, 4, etc. Thus, pH of basics can be 8, 9, 10, 11, etc.
Hence, pH of acidic solutions is less than 7 Hence, pH of basic solutions is greater than 7
pH depends upon temperature
We know from ionic product of water that at 630C, the value of Kw = 10-13.
For neutral solution we know:
Hence, pH depends upon temperature
pH of Strong Acids
Strong acids are those acids which dissociate completely in solutions. For example:
NOTE: If molarity(N) of solution is not given but normality(N) is given, then molarity can be calculated using the following formula:
N = M x n
where, n is the number of moles
pH of Weak Acids
Weak acids are those acids which dissociate partially in solutions. For example:
Strong bases
Strong bases are those bases that dissociate completely in solution. For example:
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