Admission Hack: No Calculator pH
In Dhaka University or Medical admission tests, calculators are banned. How do you find the pH of 0.005 M H₂SO₄? Here is the shortcut.
The Golden Formula
If [H+] = m × 10⁻ⁿ
Then pH = n - log(m)
Then pH = n - log(m)
Memorize These Logs
log 2 = 0.3
log 3 = 0.48
log 4 = 0.6
log 5 = 0.7
Example: 0.005 M H₂SO₄
1. H₂SO₄ is diprotic, so [H+] = 0.005 × 2 = 0.01
2. Convert to Scientific: 1 × 10⁻²
3. Apply Formula: pH = 2 - log(1)
4. pH = 2 - 0 = 2.0
Need more formulas?
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