Respuesta :
Answer:
-4
Explanation:
It went from a 7 to a 2 and 7-2 is 4, so it changed by 4 and it went down by 4.
One drop of HNO3 will cause the pH of water to change from 7 to 3
What is effect of addition of acid to pH of a water?
The pH of a solution is the negative logarithm of the hydrogen ion concentration of the solution.
- pH = - log[H⁺]
At equilibrium, the pH of water = 7
The concentration of hydrogen ions is 10⁻⁷ M
If 0.1 mL (about one drop) of 1.0 M HNO3 is added to 100 mL of water: the volume of solution is 100.1 mL and the concentration of solution is calculated thus:
C₁V₁ = C₂V₂
C₂ = C₁V₁/V₂
C₂ = 0.1 * 1/100.1
C₂ = 9.99 * 10⁻⁴ M
Hydrogen ion concentration, [H⁺] = 9.99 * 10⁻⁴ M
pH = - log(9.99 * 10⁻⁴)
pH = 3
Therefore, one drop of HNO3 will cause the pH of water to change from 7 to 3
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