1. Acids, Bases, & Salts
Regents Review

2. 1. According to the Arrhenius theory, an acid is a substance that:
A)    Changes litmus from red to blue
B)    Changes phenolphthalein from colorless to pink
C)    Produces hydronium ions as the only positive ions in an aqueous solution
D)    Produces hydroxide ions as the only negative ions in an aqueous solution
Correct Answer: Option C - Produces hydronium ions as the only positive ions in an aqueous solution

3. 1. An acidic solution could have a pH of:
B)    7
C)    10
D)    14
Correct Answer: Option A - 3.5

4. 11. Some alternate acid base theories define an acid as any species that can:
A)    Donate an electron
B)    Donate a proton
C)    Accept a proton
D)    Accept an electron
Correct Answer: Option B - Donate a proton
In the Brønsted-Lowry theory is an acid-base theory in which, an acid is defined as any chemical species that is able to lose, or "donate" a hydrogen ion (proton), and a base is a species with the ability to gain or "accept" a hydrogen ion (proton).

5. 12. When HCl(aq) is exactly neutralized by KOH(aq), the hydrogen ion concentration in the resulting mixture is:
A)    Always equal to the concentration of the hydroxide ions
B)    Sometimes greater and sometimes less than the concentration of the hydroxide ions
C)    Always less than the concentration of the hydroxide ions
D)    Always greater than the concentration of the hydroxide ions
Correct Answer: Option A - Always equal to the concentration of the hydroxide ions
Neutralization is a chemical reaction whereby an acid and a base react to form water and a salt.

6. 16. A student wishes to prepare approximately 100 milliliters of an aqueous solution of 6M HCl using 12 M HCl. Which procedure is correct?
A)    Adding 50 mL of water to 50 mL of 12 M HCl while stirring the mixture steadily.
B)    Adding 50 mL of 12 M HCl to 50 mL of water and then stirring the mixture steadily.
C)    Adding 50 mL of 12 M HCl to 50 mL of water while stirring the mixture steadily.
D)    Adding 50 mL of water to 50 mL of 12 M HCl and then stirring the mixture steadily.
Correct Answer: Option C - Adding 50 mL of 12 M HCl to 50 mL of water while stirring the mixture steadily.
Adding acid to water prevents the acid from splattering. Never add water to acid.

7. 17. In which laboratory process could a student use 0
17. In which laboratory process could a student use 0.10 M NaOH(aq) to determine the concentration of an aqueous solution of HBr?
A)    Decomposition of the solute
B)    Chromatography
C)    Evaporation of the solvent
D)    Titration
Correct Answer: Option D - Titration

8. NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
18. Given the balanced equation representing a reaction:
NH3(g) + H2O(l) → NH4+(aq) + OH-(aq)
According to one acid-base theory, the NH3(g) molecules act as
A)    An acid because they accept H+ ions
B)    An acid because they donate H+ ions
C)    A base because they accept H+ ions
D)    A base because they donate H+ ions
Correct Answer: Option C - A base because they accept H+ ions
According to the acid base theory H+ ions or hydronium ions are given out by acids and accepted by bases. Since, NH3(g) accepts H+ ion to become NH4+ in the above equation NH3 molecule acts as a base.

9. 19. What volume of 0.120M HNO3(aq) is needed to completely neutralize 150 milliliters of M NaOH(aq)?
A)    125 mL
B)    62 mL
C)    180 mL
D)    360 mL
Correct Answer: Option A mL
In titration method,
(Volume of acid) x (molarity of the acid) neutralizes an equal volume of base x the molarity of the base
VAcid x MAcid = VBase x MBase
where V = volume and M = molarity of HNO3 and NaOH.
i.e M x V = 0.100M x 150ml
Volume of HNO3 = (0.100 x 150) / 0.120
= 125mL of 0.120M HNO3

10. 20. The following data were collected at the endpoint of a titration performed to find the molarity of an HCl solution.
Volume of acid (HCl) used = 14.4 mL
Volume of base (NaOH) used = 22.4 mL
Molarity of standard base (NaOH) = 0.20 M
What is the molarity of the acid solution?
A)    1.5M
B)    0.13M
C)    0.31M
D)    0.64 M
Correct Answer: Option C M

11. 21. The reaction between hydroxyl ions and hydrogen ions is called:
A)    Analysis
B)    Neutralization
C)    Hydrolysis
D)    Decomposition
Correct Answer: Option B - Neutralization
Neutralization is a chemical reaction whereby an acid and a base react to form water and a salt.

12. 22. A water solution of H2S is:
A)    Neutral
B)    Basic
C)    Acidic
D)    Salty
Correct Answer: Option C - Acidic

13. 24. The acid present in vinegar is:
A)    Hydrogen sulfide
B)    Acetic acid
C)    Nitric acid
D)    Sulfuric acid
Correct Answer: Option B - Acetic acid

14. Correct answer: (2)

15. Correct answer: (4) BaSO4

16. Correct answer: (3) HBr

17. Correct answer: (3) H2SO4(aq) and Ca(OH)2(aq)

18. 3) is the correct answer; 

19. 3) H3PO4 is the correct answer

20. 4) KOH is the correct answer

21. (2) bromthymol blue is the correct answer.

22. Which formula represents a salt?
KOH
KCl
CH3OH
CH3COOH
Correct answer is KCl

23. Which solution will turn litmus from red to blue?
H2S(aq)
NH3(aq)
SO2(aq)
CO2(aq)
Correct answer is NH3

24. Which solution will change litmus from blue to red?
NaOH(aq)
NH4OH(aq)
CH3OH(aq)
CH3COOH(aq)
Correct Answer is CH3COOH(aq)

25. Which ion is produced when an Arrhenius base is dissolved in water?
H+, as the only positive ion in solution
H3O+, as the only positive ion in solution
OH-, as the only negative ion in solution
H-, as the only negative ion in solution
Correct Answer OH-, as the only negative ion in solution