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Sodium hydroxide [tex]\((\text{NaOH})\)[/tex] was added to pure water [tex]\(\left(\text{H}_2\text{O}\right)\)[/tex]. Which most likely were the pH values of the water before and after the sodium hydroxide was added to it?

A. Before: [tex]\(7\)[/tex], After: [tex]\(9\)[/tex]
B. Before: [tex]\(7\)[/tex], After: [tex]\(4\)[/tex]
C. Before: [tex]\(4\)[/tex], After: [tex]\(7\)[/tex]
D. Before: [tex]\(9\)[/tex], After: [tex]\(7\)[/tex]



Answer :

GinnyAnswer
Let's analyze the process step-by-step:

1. Initial pH of Pure Water:
- Pure water is neutral, meaning its pH is 7.
- Therefore, before adding anything, the pH of the water is 7.

2. Effect of Adding Sodium Hydroxide (NaOH):
- Sodium hydroxide is a strong base. When a base is added to water, it increases the concentration of hydroxide ions [tex]$\left( OH^- \right)$[/tex] in the solution.
- An increase in hydroxide ions causes the pH to increase (become more basic).

3. Assessing the Change in pH:
- Since NaOH is a strong base, adding it to the water will increase the pH from its neutral value of 7 to a higher value.
- After adding sodium hydroxide, the pH is likely to rise above 7. In this particular scenario, the pH rises to 9.

Considering these steps, the pH values are:

- Before adding sodium hydroxide: pH = 7 (neutral water)
- After adding sodium hydroxide: pH = 9 (becoming more basic)

Thus, the most likely pH values of the water before and after adding sodium hydroxide are:

Before = 7, After = 9

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