16.2.1 Strong Acids and Bases Flashcards Preview

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Flashcards in 16.2.1 Strong Acids and Bases Deck (13)
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1
Q

Strong Acids and Bases

A
  • Strong acids and strong bases completely dissociate in aqueous solution.
  • Monoprotic acids yield one proton per molecule of acid, while polyprotic acids yield two or more protons per molecule of acid.
  • The hydroxide ion concentration of strong bases made from alkali metals or alkaline earth metals can be calculated stoichiometrically.
  • Very dilute concentrations of strong acids and strong bases have less influence on the pH of the solution than the autoionization of water.
2
Q

note

A
  • Strong acids and strong bases completely dissociate in
    aqueous solution.
  • Monoprotic strong acids yield one proton per molecule of acid. Examples of monoprotic strong acids include
    hydrochloric acid (HCl) and nitric acid (HNO 3 ).
  • Polyprotic strong acids yield two or more protons per
    molecule of acid. The first dissociation is complete, but the second dissociation is not. Sulfuric acid (H 2 SO 4 ) is an example of a polyprotic strong acid.
  • The hydroxide ion concentration of strong bases made from alkali metals or alkaline earth metals can be calculated stoichiometrically.
  • Compounds formed from alkali metal ions and hydroxide ions are strong bases. For example, lithium hydroxide (LiOH) dissociates completely in water, yielding one Li + ion and one OH – ion.
  • Compounds formed from alkaline earth metal ions and
    hydroxide ions are strong bases. For example, calcium
    hydroxide (Ca(OH) 2 ) dissociates completely in water, yielding one Ca 2+ ion and two OH – ions.
3
Q

note 2

A
- Problem: What is the pH of a 1.0 x 10 –9 M solution of
hydrochloric acid (HCl).
- Hydrochloric acid is a strong acid. In most circumstances, the pH can be easily calculated from the concentration of a strong acid. However, this technique yields a pH of 9 for this solution. A pH of 9 indicates a basic solution, but HCl is a strong acid. Therefore, this calculation must be incorrect.
- Very dilute concentrations of strong acids and strong bases have less influence on the pH of the solution than the autoionization of water. The concentration of hydrogen ions in water is already 1.0 x 10 –7 M. The hydrochloric acid adds 1.0 x 10 –9 moles of hydrogen ions per liter, but this has very little effect on the total concentration. Therefore, the pH is about 7.
4
Q

What extra consideration is necessary when calculating the pH and pOH of alkaline earth hydroxides in dilute solution?

A

The alkaline earth hydroxides contribute two equivalents of hydroxide ions per mole of solution.

5
Q

What is the pH of a solution of orange juice whose hydrogen ion concentration is 2.9 × 10^−4 M?

A

3.53

6
Q

Suppose hydrobromic acid is dissolved in water to form a 0.03 M solution. What is the pH and the pOH?

A

pH = 1.52, pOH = 12.48

7
Q

What is the pH of a solution of hydrochloric acid with a concentration of 1 × 10^−4 M?

A

4

8
Q

Which of the following is not a strong acid?

A

HF

9
Q

If the pH changes by 2.00 units, by what factor does [H + ] change?

A

100

10
Q

Which of the following statements is true for strong acids and bases?

A

The concentration of hydroxide ions or protons is equal to the concentration of the substance dissolved.

11
Q

A strong acid completely dissociates in water at low concentrations. The reaction of a strong acid in water can be represented this way:

HX → H + + X −

If 0.01 moles of HX are dissolved in water to make 1.0 L of solution, which of the following statements is not true?

A

pOH = 2.0

12
Q

A solution of NaOH is prepared by dissolving 5.0 g of NaOH in 500 mL of water, then adding additional water to make 1.0 L of solution. What is the pOH and pH of this solution?

A

pOH = 0.90, pH = 13.10

13
Q

Hydrochloric acid is a monoprotic, strong acid. Which of the following is not true of a dilute solution of HCl in water?

A

Each mole of acid donates two moles of protons.

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