The pH of rain water, is approximately:

Engineering

Chemistry

Auto Ionization of Water

Environmental chemistry

Chemistry in everyday life

Question

The pH of rain water, is approximately:

5.6

6.5

7.0

7.5

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The pH of rainwater is naturally slightly acidic due to the dissolution of atmospheric carbon dioxide (CO₂) forming carbonic acid (H₂CO₃). The reaction is:

${CO}_{2} (g) + H_{2} O (l) ⇌ H_{2} {CO}_{3} (a q)$

This equilibrium gives clean, unpolluted rainwater a pH of approximately 5.6. A pH of 7.0 is neutral, and values above 7.0 are basic, which is not typical for natural rainwater without other influences.

Final Answer: $5.6$