# Which of the following aqueous solutions would test closet to pH 7

• JessicaHelena
In summary, the question asks which of the given aqueous solutions would test closest to 7 on the pH scale. After discussing the definitions of strong and weak acids and the dissociation constant, the correct answer is determined to be a) NaCl.
JessicaHelena

## Homework Statement

>Which of the following aqueous solutions would test closet to 7 on the pH scale?
$a) NaCl$, $b) Na_2CO_3$, $c) NaH_2PO_4$, $d) NaCN$

## The Attempt at a Solution

I don't understand this. So I tried writing chemical equations like for a), NaCl + H20 --> NaOH + HCl, and so on. But for example, HCl (the product in the previous equation) is a strong acid, so I thought it'd have a low pH, but apparently a) is actually the answer, and I don't know how to get that.

Perhaps you need a relevant equation ? Any candidates ?

Do the names Brønsted-Lowry ring a bell?

@Borek — yes, kind of, it was about acids and bases definition, I think.

OK, so try to apply this definition and see what are possible reactions of the substances listed.

JessicaHelena said:
I don't understand this. So I tried writing chemical equations like for a), NaCl + H20 --> NaOH + HCl, and so on. But for example, HCl (the product in the previous equation) is a strong acid, so I thought it'd have a low pH, but apparently a) is actually the answer, and I don't know how to get that.

You are correct that HCl is a strong acid. Do you know what the definition of a strong acid is? Do you know what the definition of a weak acid is?

Do you understand the dissociation constant? Knowing this constant for the acids/bases can help you.

## 1. What is the definition of pH?

pH is a measure of the acidity or basicity of a solution. It is based on the concentration of hydrogen ions present in the solution and is measured on a scale of 0 to 14, with 7 being neutral.

## 2. Why is it important to have a pH of 7 in a solution?

A pH of 7 indicates that the solution is neutral, meaning it is neither acidic nor basic. This is important because many biological processes and chemical reactions require a neutral pH to function properly.

## 3. What are some examples of solutions that would test closest to pH 7?

Some examples of solutions that would test closest to pH 7 include pure water, saliva, and blood. These solutions are considered neutral and have a pH close to 7.

## 4. How is pH measured in a solution?

pH is measured using a pH scale, which uses a special instrument called a pH meter or pH paper. The meter or paper is dipped into the solution and the resulting color or reading is compared to a chart to determine the pH level.

## 5. How does the concentration of hydrogen ions affect pH?

The concentration of hydrogen ions directly affects the pH of a solution. Higher concentrations of hydrogen ions result in a lower pH, making the solution more acidic. Lower concentrations of hydrogen ions result in a higher pH, making the solution more basic.

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