Q: A solution has a pH of 2. What is the concentration of hydrogen ions in this solution?

$$[H^+] = 1 \times 10$$^{-2}$$ mol/dm^3$

Question 1

Which of the following best describes a polyatomic ion?

Accepted Answer

A charged chemical species composed of two or more atoms covalently bonded together, acting as a single unit with a net charge.

Question 2

Which of the following is a correct example of a polyatomic ion found in common metal salts?

Accepted Answer

Sulfate ($$SO_4$$^{2-})

Question 3

According to the Arrhenius definition, which of the following substances increases the concentration of hydroxide ions (OH-) in water?

Accepted Answer

A base

Question 4

If the concentration of hydrogen ions in a solution is $$1 	imes 10$$^{-4}$$ mol/dm^3$, what is the pH of the solution?

Accepted Answer

$$pH = 4$$

Question 5

Which of the following statements about strong and weak acids is correct?

Accepted Answer

Strong acids ionize completely in water, while weak acids ionize partially.

Question 6

A solution has a pH of 2. What is the concentration of hydrogen ions in this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-2}$$ mol/dm^3$

Question 7

Which of the following best explains why a dilute solution of a strong acid can still be less dangerous than a concentrated solution of a weak acid?

Accepted Answer

Because strength refers to the percentage of ionization, not the amount of solute present.

Question 8

Which equation is used to calculate the final concentration after diluting a solution?

Accepted Answer

$$C_1V_1 = C_2V_2$$

Question 9

A laboratory technician needs to prepare 250 mL of a 0.2 M NaCl solution from a 1.0 M stock solution. What volume of the stock solution should be used?

Accepted Answer

50 mL

Question 10

Which of the following best describes the difference between concentration and strength of an acid?

Accepted Answer

Concentration refers to the amount of solute per unit volume, while strength refers to the degree of ionization.

Question 11

Which of the following solutions is most likely to have the highest electrical conductivity?

Accepted Answer

A concentrated solution of a strong acid

Question 12

If you mix equal volumes of a solution with $$[H^+] = 1 	imes 10$$^{-3}$$ mol/dm^3$ and a solution with $$[OH^-] = 1 	imes $$10^{-3}$$ mol/dm$$^3$$, what will be the resulting pH?

Accepted Answer

$$pH = 7$$

Question 13

Which of the following is a correct statement about the pH scale?

Accepted Answer

A solution with pH 1 is more acidic than a solution with pH 5.

Question 14

Which of the following best describes what happens when a weak acid is dissolved in water?

Accepted Answer

It partially ionizes, establishing an equilibrium between ions and intact molecules.

Question 15

A student adds 100 mL of 2.0 M HCl to 400 mL of water. What is the final concentration of HCl in the solution?

Accepted Answer

0.4 M

Question 16

Which of the following is NOT a property of strong acids?

Accepted Answer

They ionize partially in water.

Question 17

Which of the following best explains why pure water is neutral?

Accepted Answer

It has equal concentrations of $$H^+$$ and $$OH^-$$ ions.

Question 18

Which of the following is the correct value for Avogadro's number?

Accepted Answer

$$6.02 	imes 10$$^{23}$$

Question 19

Which of the following best describes the effect of dilution on the strength of an acid?

Accepted Answer

Dilution does not change the strength of an acid, only its concentration.

Question 20

A solution contains $$1 	imes 10$$^{-7}$$ mol/dm^3$ of H$$^+$$ ions. What is its pH and how does it compare to pure water?

Accepted Answer

pH = 7; it is neutral like pure water.

Polyatomic Ions, Acids, Bases, and Solution Chemistry: Essential Concepts for Introductory Chemistry

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