What is the pH of [tex]$6.30 \times 10^{-5} M HCl (H^+)$[/tex] solution?
Answer (2)
The pH of a solution with a hydrogen ion concentration of 6.30 × 1 0 − 5 M is approximately 4.20, indicating an acidic solution. This is calculated using the formula p H = − lo g 10 [ H + ] . Therefore, the final pH value is 4.20.
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We are given the concentration of H + ions: [ H + ] = 6.30 × 1 0 − 5 M .
Apply the formula for pH: p H = − lo g 10 [ H + ] .
Substitute the given concentration into the formula: p H = − lo g 10 ( 6.30 × 1 0 − 5 ) .
Calculate the pH value: p H ≈ 4.20 . The closest answer is 4.20 .
Explanation
Understanding the Problem We are given the concentration of H + ions in a solution of hydrochloric acid (HCl) and asked to find the pH of the solution. The pH is a measure of the acidity or basicity of a solution. The formula to calculate pH is: p H = − lo g 10 [ H + ] where [ H + ] is the concentration of hydrogen ions in moles per liter (M).
Applying the pH Formula We are given that the concentration of H + ions is 6.30 × 1 0 − 5 M . We will substitute this value into the pH formula: p H = − lo g 10 ( 6.30 × 1 0 − 5 )
Calculating the pH Now, we calculate the pH value: p H = − lo g 10 ( 6.30 × 1 0 − 5 ) ≈ 4.200659 Rounding to two decimal places, we get: p H ≈ 4.20
Final Answer The calculated pH is approximately 4.20. Comparing this to the given choices, we see that none of the choices exactly match our calculated value. However, we can infer that the closest answer is 4.20. Therefore, the correct answer is approximately 4.20.
Examples
Understanding pH is crucial in many real-world applications. For example, in agriculture, knowing the pH of the soil helps farmers determine the best crops to grow. In medicine, maintaining the correct pH balance in the body is essential for various biological processes. In environmental science, monitoring the pH of water sources helps assess pollution levels and protect aquatic life. The pH scale ranges from 0 to 14, where values less than 7 indicate acidity, 7 is neutral, and values greater than 7 indicate alkalinity or basicity.
