Question

There are two different solutions, A and B. The pH of solution A is 4. Find the pH of solution B having \([\text{H}^+]\) three times that of solution A.

• A. \(3.5229\)
• B. \(4.229\)
• C. \(3.229\)
• D. \(3.5223\)

Hint:

Use pH = -log[H+] and note that tripling [H+] subtracts log 3 from the pH.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
The pH is defined as \(\text{pH}=-\log[\text{H}^+]\). A higher hydrogen ion concentration gives a lower pH.

Step 2: Solution A
\[ \text{pH}_A=4\Rightarrow[\text{H}^+]_A=10^{-4}\ \text{M} \]

Step 3: Solution B
\[ [\text{H}^+]_B=3\times10^{-4}\ \text{M} \]
\[ \text{pH}_B=-\log(3\times10^{-4})=4-\log3 \]
Using \(\log3=0.4771\):
\[ \text{pH}_B=4-0.4771=3.5229 \]

Step 4: Check the options
The pH must be less than 4 because B is more acidic. That removes (B) 4.229. Option (C) 3.229 would need a larger rise in acidity than threefold. Option (D) 3.5223 has the wrong last digits. The correct value is 3.5229, option (A).

Final Answer:
The pH of solution B is 3.5229, option (A). \[ \boxed{3.5229} \]