For an acid solution the `[OH^(-)]` is

Options

A. `gt 10^(-7)`
B. `B lt 10^(-7)`
C. `10^(-14)`
D. `10^(-7)`

Answer

To determine the concentration of hydroxide ions \([OH^-]\) in an acidic solution, we can follow these steps:

### Step 1: Understand the relationship between \([H^+]\) and \([OH^-]\)
In any aqueous solution, the product of the concentrations of hydrogen ions \([H^+]\) and hydroxide ions \([OH^-]\) is constant at a given temperature. This relationship is described by the ionic product of water (\(K_w\)):
\[ K_w = [H^+][OH^-] \]
At 25°C, \(K_w\) is \(1.0 \times 10^{-14}\).

### Step 2: Analyze the nature of the solution
In an acidic solution, the concentration of hydrogen ions \([H^+]\) is greater than that of hydroxide ions \([OH^-]\). This means:
\[ [H^+] > [OH^-] \]

### Step 3: Determine the concentration of \([OH^-]\)
For a neutral solution at 25°C, both \([H^+]\) and \([OH^-]\) are equal to \(1.0 \times 10^{-7} \, M\). In an acidic solution, since \([H^+]\) is more than \(10^{-7} \, M\), it follows that \([OH^-]\) must be less than \(10^{-7} \, M\).

Using the equation for \(K_w\):
\[ [OH^-] = \frac{K_w}{[H^+]} \]
If \([H^+]\) is greater than \(10^{-7} \, M\), then \([OH^-]\) will be less than \(10^{-7} \, M\).

### Step 4: Conclusion
Thus, in an acidic solution, the concentration of hydroxide ions \([OH^-]\) is indeed less than \(10^{-7} \, M\).

### Final Answer
The concentration of \([OH^-]\) in an acidic solution is:
\[ [OH^-] < 10^{-7} \, M \]