Two acids A and B have pH values 1 and 5 respectively. Which is the stronger acid, A or B?

Answer

To determine which acid, A or B, is stronger based on their pH values, we can follow these steps:

### Step 1: Understand the pH scale
The pH scale ranges from 0 to 14, where:
- A pH of 7 is neutral.
- A pH less than 7 indicates acidity.
- A pH greater than 7 indicates basicity.

### Step 2: Identify the pH values of the acids
- Acid A has a pH of 1.
- Acid B has a pH of 5.

### Step 3: Determine the concentration of H⁺ ions
The pH is defined as:
\[ \text{pH} = -\log_{10}[\text{H}^+] \]
Where \([\text{H}^+]\) is the concentration of hydrogen ions.

#### For Acid A:
Given that the pH of A is 1:
\[ 1 = -\log_{10}[\text{H}^+] \]
To find \([\text{H}^+]\), we rearrange the equation:
\[ [\text{H}^+] = 10^{-1} \]
So, \([\text{H}^+] = 0.1 \, \text{mol/L}\).

#### For Acid B:
Given that the pH of B is 5:
\[ 5 = -\log_{10}[\text{H}^+] \]
Rearranging gives:
\[ [\text{H}^+] = 10^{-5} \]
So, \([\text{H}^+] = 0.00001 \, \text{mol/L}\).

### Step 4: Compare the concentrations of H⁺ ions
Now we compare the concentrations of H⁺ ions:
- For Acid A: \([\text{H}^+] = 0.1 \, \text{mol/L}\)
- For Acid B: \([\text{H}^+] = 0.00001 \, \text{mol/L}\)

Since \(0.1 \, \text{mol/L} > 0.00001 \, \text{mol/L}\), it is clear that:
\[ [\text{H}^+]_A > [\text{H}^+]_B \]

### Step 5: Conclusion
Since Acid A has a higher concentration of H⁺ ions compared to Acid B, we conclude that Acid A is the stronger acid.

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