Acid-base practice with answers

DATE: NAME: CLASS:

CHAPTER 6

Naming Acids and Bases

Review

BLM 6.1.2

ASSESSMENT

1. Fill in the following chart:

Name of pure

substance IUPAC name foracid Classical namefor acid Chemicalformula

hydrogen cyanide HBr(aq) aqueous hydrogen sulfate nitrous acid HSCN(aq) hydrogen phosphate aqueous hydrogen chlorite hydroiodic acid H3BO3(aq)

2. USING THE TRENDS YOU DISCOVERED IN QUESTION 1, FILL IN THE FOLLOWING NAMING GRID.

Ending of name of pure substance Classical name of acid

-ate

hydro---ic acid -ous acid

3. Name or give the formula of the following bases:

4.

Name of pure substance

IUPAC name for acid

Classical name for acid

Chemical Formula

hydrogen cyanide aqueous hydrogen_cyanide hydrocyanic acid HCN(aq) hydrogen bromide aqueous hydrogen_bromide hydrobromic acid HBr(aq)

hydrogen sulfate aqueous hydrogen_sulfate sulfuric acid H2SO4(aq)

hydrogen nitrite aqueous hydrogen_nitrite nitrous acid HNO2(aq)

hydrogen thiocyanate aqueous hydrogen

thiocyanate thiocyanic acid HSCN(aq)

hydrogen phosphate aqueous hydrogen

phosphate phosphoric acid H3PO4(aq)

hydrogen chlorite aqueous hydrogen_chlorite chlorous acid HClO2(aq)

hydrogen iodide aqeous hydrogen_iodide hydroiodic acid HI(aq) hydrogen borate aqueous hydrogen_borate boric acid H3BO3(aq)

5.

3.

(a) NaOH sodium hydroxide (c) strontium hydroxide Sr(OH)2(aq)

(b) Mg(OH)2 magnesium hydroxide (d) potassium hydroxide KOH(aq)

(c) NH3 ammonia (e) cesium hydroxide CsOH(aq) (Answers appear in italics.)

Ending of name of pure substance Classical name of acid

-ate -ic acid

hydrogen ----ide hydro---ic acid

CHAPTER 6

Properties of Acids and Bases

OVERHEAD

Test

Acids

Bases

litmus paper

turn blue litmus red

turn red litmus blue

pH paper

pH less than 7

pH greater than 7

electrical conductivity in

solution

conduct electric current

(electrolyte)

conduct electric current

(electrolyte)

reaction with active metals,

such as Mg(s) and Zn(s)

react to produce H2(g)

do not react with active

metals to produce H2(g)

taste

Caution:

Never taste

anything in the lab.

taste sour

taste bitter

feel

Caution:

Never deliberately

touch chemicals. Many

acids and bases can burn

your skin.

Hydronium Ions in Solution

OVERHEAD

H

O

(aq) is currently accepted as the form in which H

(aq) exists in

solution.

The polar ends of the water molecule attract the oppositely charged polar

ends of the hydrogen chloride molecule. The molecular bond between the

hydrogen and chloride ions is broken, producing hydronium, H

O

(aq), and

chloride, Cl

_{(aq), ions.}

CHAPTER 6

Strong Acids

OVERHEAD

The Strong Acids:

perchloric acid (aqueous hydrogen perchlorate), HClO

(aq)

hydroiodic acid (aqueous hydrogen iodide), HI(aq)

hydrobromic acid (aqueous hydrogen bromide), HBr(aq)

hydrochloric acid (aqueous hydrogen chloride), HCl(aq)

sulfuric acid (aqueous hydrogen sulfate), H

SO

(aq)

Strong Acids

OVERHEAD

The Strong Acids:

perchloric acid (aqueous hydrogen perchlorate), HClO

(aq)

hydroiodic acid (aqueous hydrogen iodide), HI(aq)

hydrobromic acid (aqueous hydrogen bromide), HBr(aq)

hydrochloric acid (aqueous hydrogen chloride), HCl(aq)

sulfuric acid (aqueous hydrogen sulfate), H

SO

(aq)

nitric acid (aqueous hydrogen nitrate), HNO

(aq)

CHAPTER 6

Strong Bases and Weak Bases

OVERHEAD

Common Strong Bases:

Aqueous sodium hydroxide, NaOH(aq)

Aqueous potassium hydroxide, KOH(aq)

Aqueous calcium hydroxide, Ca(OH)

(aq)

Aqueous strontium hydroxide, Sr(OH)

(aq)

Aqueous barium hydroxide, Ba(OH)

(aq)

Weak Bases in Aqueous Solution:

About 1% of ammonia molecules react in water to produce OH

_{(aq). In a}

0.10 mol/L solution of ammonia, the concentration of OH

_{(aq) is only}

Properties of Strong and Weak

Acids and Bases

ASSESSMENT

1. Fill in the chart of expected results for acids that all have a concentration of 0.1 mol/L.

Acid Chemical

formula (slightly lesspH than 7 or much

less than 7)

Conductivity

(high or low) magnesium metalReactivity with (high or low)

hydrochloric acid ethanoic acid boric acid hydrofluoric acid sulfuric acid HClO4(aq) H3PO4(aq) HBr(aq) H2SO3(aq)

2. Two different acidic solutions have a concentration of 0.1 mol/L. Solution A conducts electricity extremely well, while solution B conducts very poorly. Which of the solutions will have a lower pH? Explain using a description of what is happening on a molecular level.

3. You have two basic solutions. One has a concentration of 1.0 mol/L and one has a

concentration of 0.1 mol/L. You know one is a strong base and one is a weak base. Can you determine which solution is which based on pH? If so, explain how. If not, explain why not.

CHAPTER 6

Properties of Strong and Weak

Acids and Bases Answer Key

BLM 6.2.4A

ANSWER KEY

1.

Acid Chemical

formula (slightly lesspH than 7 or much

less than 7)

Conductivity

(high or low) magnesium metalReactivity with (high or low)

hydrochloric

acid HCl(aq) << 7 high high

ethanoic

acid CH3COOH(aq) < 7 low low

boric acid H3BO3(aq) < 7 low low

hydrofluoric

acid HF(aq) < 7 low low

sulfuric acid H2SO4(aq) << 7 high high

perchloric

acid HClO4(aq) << 7 high high

phosphoric

acid H3PO4(aq) < 7 low low

hydrobromic

acid HBr(aq) << 7 high high

sulfurous

acid H2SO3(aq) < 7 low low

(Answers appear in italics.)

2. Solution A will have a lower pH. Since it is a stronger electrolyte, it has ionized to a greater degree than B. Therefore, it is a stronger acid and has a lower pH at the same concentration.

Ion Concentration in Water

OVERHEAD

H

O(ℓ) + H

O(ℓ)

⇋

H

O

(aq) + OH

(aq)

[H

O

(aq)] = [OH

(aq)] = 1.0 × 10

mol/L

acidic solution

neutral solution

basic solution

[H

O

] > [OH

]

[H

O

] = [OH

]

[H

O

] < [OH

]

CLASS:

CHAPTER 6

Calculating Concentrations of

Acids and Bases

BLM 6.3.2

ASSESSMENT

1. Calculating Concentration from Moles and Volume:

(a) What is the concentration of acid when 0.384 moles of hydrobromic acid, HBr(aq), are dissolved in 350 mL of water?

(b)What is the concentration of base when 1.23 moles of sodium hydroxide, NaOH(aq), are dissolved in 2.5 L of water?

2. Calculating Concentration from Mass and Volume:

Calculating Concentrations of

Acids and Bases

ASSESSMENT

(b)Calculate the concentration of barium hydroxide, Ba(OH)2(aq), if 20.5 g are dissolved in 2.00 L of water.

3. Calculating Concentration from Dilutions:

(a) What is the concentration of perchloric acid, HClO4(aq), if 50.0 mL of a 2.00 mol/L solution is used to make 1.50 L of a new solution?

CHAPTER 6

Calculating Concentrations of

Acids and Bases

BLM 6.3.2

ASSESSMENT

4. Calculating Ion Concentrations from Known Acid/Base Concentrations:

(a) What is the concentration of hydronium ions, H3O+_{(aq), in a 0.35 mol/L solution of} hydroiodic acid?

(b)What is the concentration of hydroxide ions, OH–_{(aq), in a 0.380 mol/L solution of} strontium hydroxide, Sr(OH)2(aq)?

(c) What is the concentration of hydroxide ions, OH–_{(aq), in a 0.51 mol/L solution of} cesium hydroxide, CsOH(aq)?

5. Calculation Ion Concentrations from Mixed Question Types:

Calculating Concentrations of

Acids and Bases

ASSESSMENT

(b)What is the concentration of hydroxide ions, OH–_{(aq), in a solution made by} dissolving 3.6 g of solid lithium hydroxide, LiOH(aq), in 3.00L of water?

(c) What is the concentration of hydroxide ions, OH–_{(aq), in a solution made by} dissolving 2.93 g of solid barium hydroxide, Ba(OH)2(s), in 2.50 L of water?

(d)A new dilute solution with a volume of 250 mL is made by taking 50.0 mL of a 0.45 mol/L strontium hydroxide, Sr(OH)2(aq), solution. What is the concentration of hydroxide ion, OH–_{(aq), in this new solution?}

Calculating Concentrations of Acids

and Bases Answer Key

1. (a)

(b)

2. (a)

(b)

3. (a)

(b)

4. (a)

(b)

(c)

CHAPTER 6

Calculating Concentrations of Acids

and Bases Answer Key

BLM 6.3.2A

5. (a)

(b)

(c)

The pH Scale

OVERHEAD

CLASS:

CHAPTER 6

Calculating pH

ASSESSMENT

1. What is the pH of the following solutions given their hydronium ion concentrations?

(a) [H3O+_{(aq)] = 5.32 × 10}–7 _mol/L

(b)[H3O+_{(aq)] = 6.1 × 10}–5 _mol/L

(c) [H3O+_{(aq)] = 2.679 × 10}–14 _mol/L

2. Which of the above solutions would be considered acidic?

3. Fill in the following chart:

[H3O+(aq)] (mol/L) pH 1.37 × 10–2

2.38 × 10–5 2.38 × 10–6 1.00 × 10–7 3.45 × 10–9 3.45 × 10–10 3.45 × 10–11 5.33 × 10–12

4. Notice in the chart that the concentration of H3O+_{(aq) is continually decreasing. What do you} notice about the pH values?

5. Generalize what happens to pH as acidity decreases.

6. What do you think happens to pH as basicity decreases?

CHAPTER 6

Calculating pH

BLM 6.3.2

ASSESSMENT

7. Find some spots on the table when the pH increases by exactly 1 pH unit. What do you notice about the change in concentration of hydronium ions at these points?

8. Find a spot on the table when the pH increases by exactly 2 pH units. What do you notice about the change in concentration of hydronium ions at these points?

10.What is the pH of the following solutions?

(a) a 0.563 mol/L solution of nitric acid, HNO3(aq)

(b)a 2.3 × 10-4 _{mol/L solution of hydroiodic acid, HI(aq)}

(c) a 9.342 × 10-5 _{mol/L solution of perchloric acid, HClO4(aq)}

CHAPTER 6

Calculating pH

BLM 6.3.2

ASSESSMENT

11.What is the pH of a solution made by the following methods?

(a) dissolving 3.62 g of pure hydrogen perchlorate, HClO4(aq), in 2.0 L of water

Calculating pH Answer Key

ANSWER KEY

1. (a) pH = –log [H3O+_(aq)]

pH = –log(5.32 × 10–7 _mol/L) pH = 6.274

(b) pH = –log [H3O+_(aq)] pH = –log(6.1 × 10–5 _mol/L) pH = 4.21

(c) pH = –log [H3O+_(aq)]

pH = –log(2.679 × 10–14 _mol/L) pH = 13.5720

2. Solutions (a), (b), and (d) would be considered acidic.

3.

4. As the concentration of H3O+_{(aq) decreases, pH values increase.}

5. As acidity decreases, pH increases.

6. As basicity decreases, pH decreases.

7. For every pH increase of one unit, the concentration of H3O+_{(aq) decreases by a factor of ten.}

8. For every pH increase of two units, the concentration of H3O+_{(aq) decreases by a factor of} 102_{, or 100.}

9. You would expect the pH to increase by three units if an acidic solution is diluted by a factor of 103_.

10. (a) pH = –log [H3O+_(aq)] [H3O+_{(aq)] = 0.563 mol/L} pH = 0.249

(b) pH = –log[H3O+_(aq)]

[H3O+_{(aq)] = 2.3 × 10}–4 _mol/L

pH = 3.64 CHAPTER 6

Calculating pH Answer Key

BLM 6.3.4A

ANSWER KEY

[H3O+(aq)] (mol/L) pH

1.37 × 10-2 _1.863

2.38 × 10-5 _4.623

2.38 × 10-6 _5.623

1.00 × 10-7 _7.000

3.45 × 10-9 _8.462

(b)

CHAPTER 6

Calculating pH Answer Key

BLM 6.3.4A

ANSWER KEY

CHAPTER 6

Calculating pH After Dilution

ASSESSMENT

1. A 35.0 mL volume of a 0.489 mol/L solution of hydrochloric acid is diluted to a volume of 300 mL.

(a) What is the pH of the concentrated solution?

(b)What is the concentration of the diluted solution?

(c) What is the pH of the diluted solution?

(d)Compare your answers to (a) and (c). Considering the acid solution has been diluted, do your answers make sense?

Calculating pH After Dilution

(continued)

ASSESSMENT

3. A concentrated solution is made by dissolving 3.5 g of hydrobromic acid in 20.0L of water. A 50.0 mL volume of the concentrated solution is then used to make 100 L of a new

solution. What is the pH of the new solution?

4. Why might the dilute solution in Question 3 be made using a dilution as described instead of just dissolving a solid into the full 100 L?

Calculating pH After Dilution

Answer Key

ANSWER KEY

1. (a)

(b)

(c)

(d) The answers do make sense. As the concentration of the acid decreases, pH increases.

Calculating pH After Dilution

Answer Key

ANSWER KEY

3.

CLASS:

CHAPTER 6

Calculating pOH and Changing

from pH to pOH

BLM 6.3.10

ASSESSMENT

1. What is the pOH of the following solutions given their hydroxide ion concentrations?

(a) [OH–_{(aq)] = 4.67 × 10}–3 _mol/L

(b)[OH–_{(aq)] = 5.84 × 10}–8 _mol/L

(c) [OH–_{(aq)] = 1.478 × 10}–14 _mol/L

(d)[OH–_{(aq)] = 3.4 × 10}–2 _mol/L

2. Which of the above solutions are considered acidic?

3. If given the pH of the following solution, give the pOH, or vice versa:

(a) pH = 12.3

(b)pOH = 5.5

(c) pOH = 2.95

(d)pH = 6.629

(e) pOH = 1.1

4. Fill in the following chart:

[OH–_{(aq)] mol/L pOH pH}

5. Compare and contrast what happens to pH as acidity increases to what happens to pOH.

CHAPTER 6

Calculating pOH and changing

from pH to pOH

BLM 6.3.10

ASSESSMENT

6. What is the pOH of a 3.2 mol/L solution of lithium hydroxide, LiOH(aq)?

7. What is the pOH of a 5.467 mol/L solution of strontium hydroxide, Sr(OH)2(aq)?

8. What is the pH of a 3.45 mol/L solution of sodium hydroxide, NaOH(aq)?

9. What is the pOH of a solution made by dissolving 4.95 g of potassium hydroxide, KOH(aq), in 4.50 L of water?

Calculating pOH and Changing

from pH to pOH Answer Key

ANSWER KEY

1. (a)

(b)

(c)

2. Solutions (b) and (c) are acidic.

3. pH = 14 – pOH pOH = 14 – pH

(a) pOH = 1.7

(b)pH = 8.5

(c) pH = 11.05

(d)pOH = 7.371

(e) pH = 12.9

4.

*Note that two of the answers show a negative pH or pOH. While the pH and pOH scales were defined so that most acidic and basic solutions would fall within the range from 0 to 14, it is possible for concentrated strong acids or bases to fall outside this range.

CHAPTER 6

Calculating pOH and Changing

from pH to pOH Answer Key

(continued)

BLM 6.3.10A

ANSWER KEY

5. As acidity increases, pH decreases and pod increases.

6.

7.

[OH–_{(aq)] mol/L pOH pH}

1.28 –0.107 14.107

5.35 × 10–3 _{2.272 11.728}

8.459 × 10–5 _{4.0727 9.9273}

9.6 × 10–8 _{7.02 6.98}

8.

Understanding pH and pOH

OVERHEAD

pH + pOH = 14.00

Range of acidity

and basicity [H3O

+_{(aq)] (mol/L) Exponential}

notation (mol/L)

pH

(-log[H3O+(aq)])

pOH (14-pH)

very acidic 1 1 × 100 _{0.0 14.0}

0.1 1 × 10–1 _{1.0 13.0}

0.01 1 × 10–2 _{2.0 12.0}

0.001 1 × 10–3 _{3.0 11.0}

0.0001 1 × 10–4 _{4.0 10.0}

0.000 01 1 × 10–5 _{5.0 9.0}

0.000 001 1 × 10–6 _{6.0 8.0}

neutral [H3O+(aq)]

= [OH–_(aq)]

= 1 × 10–7 _mol/L 0.000 000 1 1 × 10

–7 _{7.0 7.0}

0.000 000 01 1 × 10–8 _{8.0 6.0}

0.000 000 001 1 × 10–9 _{9.0 5.0}

0.000 000 000 1 1 × 10–10 _{10.0 4.0}

0.000 000 000 01 1 × 10–11 _{11.0 3.0}

0.000 000 000 001 1 × 10–12 _{12.0 2.0}

0.000 000 000 000 1 1 × 10–13 _{13.0 1.0}

CHAPTER 6

Calculating Concentration from pH

and pOH

BLM 6.3.12

ASSESSMENT

1. What is the concentration of hydronium ions in the following solutions given their pH values?

(a) pH = 2.34

(b)pH = 15.6

(c) pH = 4.4

(d)pH = 1.892

(e) pH = 5.63

2. What is the concentration of hydroxide ions in the following solutions given the following information?

(a) pOH = 1.45

(b)pOH = 10.672

(c) pOH = 7.3

(d)pH = 2.982

(e) pH = 4.932

(f) pH = 10 .2

3. What is the concentration of hydrochloric acid, HCl(aq), that gives a solution with a pH of 3.69?

Calculating concentration from pH

and pOH

ASSESSMENT

5. What is the concentration of sodium hydroxide, NaOH(aq), that gives a solution with a pH of 10.32?

6. What is the concentration of barium hydroxide, Ba(OH)2(aq), that gives a solution with a pH of 11.836?

7. Is it possible to make an aqueous solution with strontium hydroxide, Sr(OH)2(aq), that gives a pOH of 10.54? If so calculate it. If not, explain why not.

8. What mass of hydrogen chloride gas, HCl(g), needs to be dissolved in 2.00 L of water to create a solution with a pH of 3.298?

9. What mass of rubidium hydroxide, RbOH(s), needs to be dissolved in 1.50 L of water to create a solution with a pH of 9.35?

CHAPTER 6

Calculating Concentration from

pH and pOH Answer Key

BLM 6.3.12A

ANSWER KEY

1. (a) (b) (c) (d)

(e)

2. (a)

(b) (c) (d) (e)

(f)

3.

Calculating Concentration from

pH and pOH Answer Key

ANSWER KEY

6.

7. This solution is acidic. You can’t make a basic solution acidic through dilution.

8.

9.

Putting it all Together (Dilutions

as Advanced Acid- Base

Calculations)

ASSESSMENT

1. A 50 mL volume of a 0.7983 mol/L solution of sodium hydroxide, NaOH(aq), is diluted to a volume of 1.50L.

(a) What is the pOH of the concentrated solution?

(b)What is the pH of the concentrated solution?

(c) What is the concentration of the dilute solution?

(d)What is the pOH of the dilute solution?

(e) What is the pH of the dilute solution?

(f) Compare your answers for (b) and (e)? Do they make sense considering the basic solution was diluted?

Putting it all Together (Dilutions

as Advanced Acid- Base

Calculations)

ASSESSMENT

(b)What is the concentration of hydronium ions in the dilute solution?

(c) What is the pH of the new solution?

(d)Does your answer to (c) make sense?

3. A 35.0 mL solution of a strong acid solution with a pH of 2.674 is diluted to make 8.00 L of solution. What is the pH of the new solution?

4. What volume of a strong acid solution with a pH of 3.24 is required to make 20 L of a solution with a pH of 6.54.

5. A 15.0 mL volume of a strong base solution with a pH of 8.729 is used to make 500 mL of a dilute solution. (Note: because it is a basic solution, we must work with the concentration of hydroxide ions, not the concentration of hydronium ions.)

Putting it all Together (Dilutions

as Advanced Acid-Base

Calculations)

ASSESSMENT

(b) What is the concentration of hydroxide ions in the concentrated solution?

(c) What is the concentration of hydroxide ions in the dilute solution?

(d)What is the pOH of the dilute solution?

(e) What is the pH of the dilute solution?

(f) Does your answer to (e) make sense?

6. A 20.0 mL volume of a strong base solution with a pH of 11.35 is used to make 12.00 L of a dilute solution. What is the pH of the new solution?

Putting it all Together (Dilutions as

Advanced Acid- Base Calculations)

Answer Key

ANSWER KEY

1. (a)

(b) pH  14.00  pOH  13.9022

(c)

(d)

(e) pH  14.00  pOH  12.43

(f) Yes. As the concentration of the base decreases, pH decreases.

2. (a) (b)

(c)

(d) Yes, as an acid is diluted, pH increases.

3.

4.

Putting it all Together (Dilutions as

Advanced Acid-Base Calculations)

Answer Key

ANSWER KEY

5.

(b)

(c)

(d)

(e)pH  7.207

(f) Yes, since pH should decrease as the concentration of decreases.

6.