Question 1

Select the best statement relating to the following reaction: 2MnO₂(s) + KClO₃(aq) + 2KOH(aq) → 2KMnO₄(aq) + KCl(aq) + H₂O(l)

Accepted Answer

The answer of Select the best statement relating to the...

Question 2

In a redox reaction, electrons are transferred

Accepted Answer

In a redox reaction, electrons are transferred from the substance being oxidized (losing electrons) to the substance being reduced (gaining electrons). This transfer of electrons is what causes the oxidation-reduction reaction, giving rise to a change in the oxidation states of the substances involved. The reducing agent is what causes the substance being reduced to gain electrons, while the oxidizing agent is what causes the substance being oxidized to lose electrons. Therefore, choice D is the correct answer as it represents the transfer of electrons from the substance being oxidized to the substance being reduced.

Question 3

Which of the statements below correctly describes the combustion of glucose, shown below? C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Accepted Answer

The answer of Which of the statements below correctly describes...

Question 4

A standard solution of 0.243 M NaOH was used to determine the concentration of a hydrochloric acid solution. If 46.33 mL of NaOH is needed to neutralize 10.00 mL of the acid, what is the molar concentration of the acid?

Accepted Answer

First, we need to use the balanced chemical equation for the neutralization reaction:

HCl + NaOH → NaCl + H2O

We can see that the mole ratio between NaOH and HCl is 1:1, which means that the moles of NaOH used will be equal to the moles of HCl present in the solution.

Using the concentration and volume of NaOH used, we can calculate the moles of NaOH used:

mol NaOH = concentration × volume = 0.243 M × 0.04633 L = 0.01124 mol

Since the mole ratio is 1:1, the moles of HCl present in the solution will also be 0.01124 mol. We can calculate the molar concentration of the acid solution as follows:

concentration = moles ÷ volume = 0.01124 mol ÷ 0.01000 L = 1.13 M

Therefore, the correct answer is C.

Question 5

Ammonia, NH₃, produces hydroxide ions in aqueous solution by

Accepted Answer

Ammonia acts as a base by accepting a proton from a water molecule, forming NH4+ and OH- ions.

Question 6

Calculate the oxidation number of the chlorine in perchloric acid, HClO₄, a strong oxidizing agent.

Accepted Answer

Perchloric acid has a formula of HClO4. The oxidation number of hydrogen is always +1, and the oxidation number of oxygen is typically -2. We can assign x as the oxidation number of chlorine. Therefore, we can set up the equation:
(+1) + x + 4(-2) = 0 (the sum of the oxidation numbers in a compound is equal to zero)
Solving for x, we get x = +7. Therefore, the oxidation number of chlorine in perchloric acid is +7.

Question 7

Sodium tripolyphosphate is used in detergents to make them effective in hard water. Calculate the oxidation number of phosphorus in Na₅P₃O₁₀.

Accepted Answer

In the compound, the oxidation number of sodium is +1 and the oxidation number of oxygen is -2. Since the compound is neutral, the sum of the oxidation numbers of all the elements is zero. Therefore, the sum of the oxidation numbers of sulfur is 0 and the sum of the oxidation numbers of phosphorus must also be 0. Since there are 5 oxygen atoms, and each oxygen atom has an oxidation number of -2, the total oxidation number contributed by oxygen is -10. Therefore, the oxidation number of phosphorus must be +5 to balance out the sum of the oxidation numbers.

Question 8

Vinegar is a solution of acetic acid, CH₃COOH, dissolved in water. A 5.54-g sample of vinegar was neutralized by 30.10 mL of 0.100 M NaOH. What is the percent by weight of acetic acid in the vinegar?

Accepted Answer

First, we need to calculate the amount of NaOH used:

0.100 M x 30.10 mL = 0.00301 moles NaOH

Since acetic acid and NaOH react in a 1:1 ratio, we know that the amount of acetic acid in the vinegar is also 0.00301 moles.

Next, we can calculate the molecular weight of acetic acid:

2(12.01 g/mol) + 2(1.01 g/mol) + 16.00 g/mol = 60.05 g/mol

Now we can calculate the percent by weight of acetic acid in the vinegar:

(0.00301 moles x 60.05 g/mol) / 5.54 g x 100% = 32.6%

Therefore, the answer is (C) 3.26%.

Question 9

The oxidation numbers of P, S, and Cl in H₂PO₂^-, H₂S, and KClO₄ are, respectively

Accepted Answer

In H₂PO₂⁻, P has an oxidation number of +1. In H₂S, S has an oxidation number of -2. In KClO₄, Cl has an oxidation number of +7.

Question 10

Which of the following is a weak base?

Accepted Answer

NH3 is a weak base. It is not a strong base like Ca(OH)2 and Ba(OH)2, and it does not dissociate completely in water like NaOH. CH3COOH is an acid, not a base.

Question 11

Sodium thiosulfate, Na₂S₂O₃, is used as a "fixer" in black and white photography. Identify the reducing agent in the reaction of thiosulfate with iodine. 2S₂O₃²^-(aq) + I₂(aq) → S₄O₆²^-(aq) + 2I^-(aq)

Accepted Answer

In the reaction, sodium thiosulfate (Na2S2O3) acts as the reducing agent as it donates electrons to iodine (I2), reducing it to iodide ions (I-), while the thiosulfate itself is oxidized to tetrathionate (S4O6^2-).

Question 12

Identify the oxidizing agent in the following redox reaction. Hg²⁺(aq) + Cu(s) → Cu²⁺(aq) + Hg(l)

Accepted Answer

The oxidizing agent is the species that gets reduced by gaining electrons. In this reaction, HgS (with Hg in a +2 oxidation state) is reduced to Hg (liquid, with an oxidation state of 0), indicating it is the oxidizing agent.

Question 13

A 0.00100 mol sample of Ca(OH)₂ requires 25.00 mL of aqueous HCl for neutralization according to the reaction below. What is the concentration of the HCl? Equation: Ca(OH)₂(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l)

Accepted Answer

The answer of A 0.00100 mol sample of Ca(OH)₂ requires...

Question 14

Which one of the following substances is a strong acid?

Accepted Answer

HNO3 is a strong acid, meaning it completely dissociates in water to release H+ ions. The other options are either weak acids or not acids at all.

Question 15

Select the correct set of products for the following reaction. Ba(OH)₂(aq) + HNO₃(aq) →

Accepted Answer

The products of the reaction are Ba(NO3)2 and H2O. This is because Ba(OH)2 and HNO3 will react to form Ba(NO3)2 and H2O, according to the following balanced chemical equation:

Ba(OH)2 + 2HNO3 → Ba(NO3)2 + 2H2O

The state symbols for the products are not given in the question, but based on the solubility rules for nitrates and sulfates, Ba(NO3)2 is soluble in water and will remain in the aqueous phase, while BaSO4 is insoluble and will precipitate out as a solid. Therefore, option A is incorrect because BaSO4 is not a product of the reaction. Option C is incorrect because Ba is not a product of the reaction, and both NO2 and H2O are in the gas phase. Option D is incorrect because BaSO4 is not a product of the reaction, and NO2 is in the gas phase, not the solid phase. Option E is incorrect because a reaction does occur, and products are formed.

Question 16

What is the oxidation number of iodine in I₂.

Accepted Answer

Iodine is in its elemental form in I2, which has an oxidation number of 0.

Question 17

Automobile batteries use 3.0 M H₂SO₄ as an electrolyte. How much 1.20 M NaOH will be needed to neutralize 225 mL of battery acid? H₂SO₄(aq) + 2NaOH(aq) → 2H₂O(l) + Na₂SO₄(aq)

Accepted Answer

The answer of Automobile batteries use 3.0 M H₂SO₄ as...

Question 18

Select the net ionic equation for the reaction between lithium hydroxide and hydrobromic acid. LiOH(aq) + HBr(aq) → H₂O(l) + LiBr(aq)

Accepted Answer

The net ionic equation for the reaction between lithium hydroxide and hydrobromic acid is $H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$, which shows the hydrogen ion from the acid reacting with the hydroxide ion from the base to form water.

Question 19

Calculate the oxidation number of sulfur in sodium metabisulfite, Na₂S₂O₅.

Accepted Answer

In Na2S2O5, the oxidation state of sodium is +1 and oxygen is -2. The total charge of Na and O is (+1)x2 + (-2)x5 = -8. Therefore, the total charge contributed by the sulfur atoms must be +8 in order to balance the overall charge of the compound, since it is an ionic compound. 
Let x be the oxidation state of sulfur. 
2(+1) + 2x + 5(-2) + 1(-1) = 0 
2x - 8 = 0 
2x = 8 
x = +4 
Therefore, the oxidation state of sulfur in Na2S2O5 is +4.

Question 20

How many milliliters of 1.58 M HCl are needed to react completely with 23.2 g of NaHCO₃(ℳ = 84.02 g/mol)? HCl(aq) + NaHCO₃(s) → NaCl(s) + H₂O(l) + CO₂(g)

Accepted Answer

First, calculate moles of NaHCO₃: 23.2 g / 84.02 g/mol = 0.276 mol. The reaction is 1:1, so 0.276 mol of HCl is needed. Using the concentration of HCl (1.58 M), calculate volume: 0.276 mol / 1.58 mol/L = 0.175 L, which is 175 mL.

Quiz 4: Three Major Classes of Chemical Reactions

Select the best statement relating to the following reaction: 2MnO₂(s) + KClO₃(aq) + 2KOH(aq) → 2KMnO₄(aq) + KCl(aq) + H₂O(l)

In a redox reaction, electrons are transferred

Which of the statements below correctly describes the combustion of glucose, shown below? C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

A standard solution of 0.243 M NaOH was used to determine the concentration of a hydrochloric acid solution. If 46.33 mL of NaOH is needed to neutralize 10.00 mL of the acid, what is the molar concentration of the acid?

Ammonia, NH₃, produces hydroxide ions in aqueous solution by

Calculate the oxidation number of the chlorine in perchloric acid, HClO₄, a strong oxidizing agent.

Sodium tripolyphosphate is used in detergents to make them effective in hard water. Calculate the oxidation number of phosphorus in Na₅P₃O₁₀.

Vinegar is a solution of acetic acid, CH₃COOH, dissolved in water. A 5.54-g sample of vinegar was neutralized by 30.10 mL of 0.100 M NaOH. What is the percent by weight of acetic acid in the vinegar?

The oxidation numbers of P, S, and Cl in H₂PO₂^-, H₂S, and KClO₄ are, respectively

Which of the following is a weak base?

Sodium thiosulfate, Na₂S₂O₃, is used as a "fixer" in black and white photography. Identify the reducing agent in the reaction of thiosulfate with iodine. 2S₂O₃²^-(aq) + I₂(aq) → S₄O₆²^-(aq) + 2I^-(aq)

Identify the oxidizing agent in the following redox reaction. Hg²⁺(aq) + Cu(s) → Cu²⁺(aq) + Hg(l)

A 0.00100 mol sample of Ca(OH) ₂ requires 25.00 mL of aqueous HCl for neutralization according to the reaction below. What is the concentration of the HCl? Equation: Ca(OH) ₂(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l)

Which one of the following substances is a strong acid?

Select the correct set of products for the following reaction. Ba(OH) ₂(aq) + HNO₃(aq) →

What is the oxidation number of iodine in I₂.

Automobile batteries use 3.0 M H₂SO₄ as an electrolyte. How much 1.20 M NaOH will be needed to neutralize 225 mL of battery acid? H₂SO₄(aq) + 2NaOH(aq) → 2H₂O(l) + Na₂SO₄(aq)

Select the net ionic equation for the reaction between lithium hydroxide and hydrobromic acid. LiOH(aq) + HBr(aq) → H₂O(l) + LiBr(aq)

Calculate the oxidation number of sulfur in sodium metabisulfite, Na₂S₂O₅.

How many milliliters of 1.58 M HCl are needed to react completely with 23.2 g of NaHCO₃(ℳ = 84.02 g/mol) ? HCl(aq) + NaHCO₃(s) → NaCl(s) + H₂O(l) + CO₂(g)

Quiz 4: Three Major Classes of Chemical Reactions

Select the best statement relating to the following reaction: 2MnO2(s) + KClO3(aq) + 2KOH(aq) → 2KMnO4(aq) + KCl(aq) + H2O(l)

In a redox reaction, electrons are transferred

Which of the statements below correctly describes the combustion of glucose, shown below? C6H12O6 + 6O2 → 6CO2 + 6H2O

A standard solution of 0.243 M NaOH was used to determine the concentration of a hydrochloric acid solution. If 46.33 mL of NaOH is needed to neutralize 10.00 mL of the acid, what is the molar concentration of the acid?

Ammonia, NH3, produces hydroxide ions in aqueous solution by

Calculate the oxidation number of the chlorine in perchloric acid, HClO4, a strong oxidizing agent.

Sodium tripolyphosphate is used in detergents to make them effective in hard water. Calculate the oxidation number of phosphorus in Na5P3O10.

Vinegar is a solution of acetic acid, CH3COOH, dissolved in water. A 5.54-g sample of vinegar was neutralized by 30.10 mL of 0.100 M NaOH. What is the percent by weight of acetic acid in the vinegar?

The oxidation numbers of P, S, and Cl in H2PO2-, H2S, and KClO4 are, respectively

Which of the following is a weak base?

Sodium thiosulfate, Na2S2O3, is used as a "fixer" in black and white photography. Identify the reducing agent in the reaction of thiosulfate with iodine. 2S2O32-(aq) + I2(aq) → S4O62-(aq) + 2I-(aq)

Identify the oxidizing agent in the following redox reaction. Hg2+(aq) + Cu(s) → Cu2+(aq) + Hg(l)

A 0.00100 mol sample of Ca(OH) 2 requires 25.00 mL of aqueous HCl for neutralization according to the reaction below. What is the concentration of the HCl? Equation: Ca(OH) 2(s) + 2HCl(aq) → CaCl2(aq) + H2O(l)

Which one of the following substances is a strong acid?

Select the correct set of products for the following reaction. Ba(OH) 2(aq) + HNO3(aq) →

What is the oxidation number of iodine in I2.

Automobile batteries use 3.0 M H2SO4 as an electrolyte. How much 1.20 M NaOH will be needed to neutralize 225 mL of battery acid? H2SO4(aq) + 2NaOH(aq) → 2H2O(l) + Na2SO4(aq)

Select the net ionic equation for the reaction between lithium hydroxide and hydrobromic acid. LiOH(aq) + HBr(aq) → H2O(l) + LiBr(aq)

Calculate the oxidation number of sulfur in sodium metabisulfite, Na2S2O5.

How many milliliters of 1.58 M HCl are needed to react completely with 23.2 g of NaHCO3 (ℳ = 84.02 g/mol) ? HCl(aq) + NaHCO3(s) → NaCl(s) + H2O(l) + CO2(g)

Select the best statement relating to the following reaction: 2MnO₂(s) + KClO₃(aq) + 2KOH(aq) → 2KMnO₄(aq) + KCl(aq) + H₂O(l)

Which of the statements below correctly describes the combustion of glucose, shown below? C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Ammonia, NH₃, produces hydroxide ions in aqueous solution by

Calculate the oxidation number of the chlorine in perchloric acid, HClO₄, a strong oxidizing agent.

Sodium tripolyphosphate is used in detergents to make them effective in hard water. Calculate the oxidation number of phosphorus in Na₅P₃O₁₀.

Vinegar is a solution of acetic acid, CH₃COOH, dissolved in water. A 5.54-g sample of vinegar was neutralized by 30.10 mL of 0.100 M NaOH. What is the percent by weight of acetic acid in the vinegar?

The oxidation numbers of P, S, and Cl in H₂PO₂^-, H₂S, and KClO₄ are, respectively

Sodium thiosulfate, Na₂S₂O₃, is used as a "fixer" in black and white photography. Identify the reducing agent in the reaction of thiosulfate with iodine. 2S₂O₃²^-(aq) + I₂(aq) → S₄O₆²^-(aq) + 2I^-(aq)

Identify the oxidizing agent in the following redox reaction. Hg²⁺(aq) + Cu(s) → Cu²⁺(aq) + Hg(l)

A 0.00100 mol sample of Ca(OH) ₂ requires 25.00 mL of aqueous HCl for neutralization according to the reaction below. What is the concentration of the HCl? Equation: Ca(OH) ₂(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l)

Select the correct set of products for the following reaction. Ba(OH) ₂(aq) + HNO₃(aq) →

What is the oxidation number of iodine in I₂.

Automobile batteries use 3.0 M H₂SO₄ as an electrolyte. How much 1.20 M NaOH will be needed to neutralize 225 mL of battery acid? H₂SO₄(aq) + 2NaOH(aq) → 2H₂O(l) + Na₂SO₄(aq)

Select the net ionic equation for the reaction between lithium hydroxide and hydrobromic acid. LiOH(aq) + HBr(aq) → H₂O(l) + LiBr(aq)

Calculate the oxidation number of sulfur in sodium metabisulfite, Na₂S₂O₅.

How many milliliters of 1.58 M HCl are needed to react completely with 23.2 g of NaHCO₃(ℳ = 84.02 g/mol) ? HCl(aq) + NaHCO₃(s) → NaCl(s) + H₂O(l) + CO₂(g)