High School Chemistry : Help with Acid-Base Reactions

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #22 : Acid Base Chemistry

What volume of a 1.2M solution of hydrochloric acid is needed to neutralize 50mL of a 3M sodium hydroxide solution?

Possible Answers:

\(\displaystyle 130mL\)

\(\displaystyle 125mL\)

\(\displaystyle 100mL\)

\(\displaystyle 50mL\)

\(\displaystyle 200mL\)

Correct answer:

\(\displaystyle 125mL\)

Explanation:

The equation to use here is:

\(\displaystyle (M_A)(V_A)=(M_B)(V_B)\)

Here, \(\displaystyle M_A\) is the molarity of the acid, \(\displaystyle V_A\) is the volume of the acid, \(\displaystyle M_B\) is the molarity of the base, and \(\displaystyle V_B\) is the volume of the base. Don't forget to convert the volume to liters!

\(\displaystyle (1.2M)V_A=(3M)(0.050L)\)

\(\displaystyle V_A=\frac{(3M)(0.050L)}{1.2M}=0.125L=125mL\)

Example Question #22 : Acid Base Chemistry

What kind of reaction is an acid-base neutralization reaction?

Possible Answers:

Decomposition

Addition (synthesis)

Double-replacement

Oxidation-reduction

Single-replacement

Correct answer:

Double-replacement

Explanation:

Below is a generic acid-base neutralization reaction:

\(\displaystyle HA+BOH\rightarrow H_2O + AB\)

The products are always water, and a salt. This salt is produced from the resulting ions \(\displaystyle A^-\) and \(\displaystyle B^+\). The \(\displaystyle H\) from the acid replaces the \(\displaystyle B\) from the base, and the \(\displaystyle A\) from the acid replaces the \(\displaystyle OH\) from the base. Since there are two replacements, acid-base neutralizations are classified as double-replacement reactions.

Example Question #23 : Acid Base Chemistry

Which of the following is the definition for an Arrhenius acid?

Possible Answers:

A substance that increases the \(\displaystyle H^+\) concentration when added to water

A proton acceptor

A proton donor

None of these

A substance that increases the \(\displaystyle OH^-\) concentration when added to water.

Correct answer:

A substance that increases the \(\displaystyle H^+\) concentration when added to water

Explanation:

Arrhenius acid/base theory was created by Swedish chemist Svante Arrhenius, and is the oldest acid/base classification. According to his classification, acids are compounds that increase the concentration of \(\displaystyle H^+\) ions in a solution, while bases are compounds or elements that either decrease the concentration of \(\displaystyle H^+\) ions in solution or increase the concentration of \(\displaystyle OH^-\) ions in a solution. The other two answers describe the Brønsted–Lowry theory of acids and bases.

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