Question 1

Using the following portion of the activity series for oxidation half reactions,determine which combination of reactants will result in a reaction. Ca(s)→ Ca²⁺(aq)+ 2 e^- Ag(s)→ Ag⁺(aq)+ e^- A)Ca(s)with Ag(s) B)Ca(s)with Ag⁺(aq) C)Ca²⁺(aq)with Ag⁺(aq) D)Ca²⁺(aq)with Ag(s)

Accepted Answer

Calcium is more reactive than silver, so it can displace silver from its compounds in solution, but not the other way around.

Question 2

Which element will react rapidly with aqueous H⁺ ions and also with liquid H₂O? A)Pt B)Co C)Zn D)Ca

Accepted Answer

Calcium (Ca) reacts rapidly with both aqueous H⁺ ions and liquid H₂O, forming hydrogen gas and calcium hydroxide.

Question 3

Which element will not react with liquid water or with aqueous H⁺ ions? A)Hg B)Co C)Zn D)Li

Accepted Answer

Mercury (Hg) does not react with liquid water or with aqueous H⁺ ions due to its low reactivity and inability to displace hydrogen from water or react with the given ions.

Question 4

Using the following portion of the activity series for oxidation half reactions Mg(s)→ Mg²⁺(aq)+ 2e^- Co(s)→ Co²⁺(aq)+ 2e^- Cu(s)→ Cu²⁺(aq)+ 2e^- indicate which pairs of reactions will occur. A)Cu(s)with Co²⁺(aq)and Co(s)with Mg²⁺(aq) B)Mg(s)with Cu²⁺(aq)and Co²⁺(aq)with Mg²⁺(aq) C)Mg(s)with Cu(s)and Co(s)with Cu(s) D)Mg(s)with Co²⁺(aq)and Co(s)with Cu²⁺(aq)

Accepted Answer

According to the activity series, magnesium can displace cobalt and copper from their sulfates. Hence, Mg(s) can react with Co²⁺(aq) and Co(s) can react with Cu²⁺(aq).

Question 5

Which elementwill not react with liquid water but will react with aqueous H⁺ ions and steam? A)K B)Fe C)Sn D)Hg

Accepted Answer

Fe (iron) does not react with liquid water under normal conditions but will react with steam to form iron oxide and hydrogen gas. It also reacts with aqueous H⁺ ions (sulfate ions, assuming a typographical error in the chemical formula) to form iron sulfate.

Question 6

How many milliliters of 0.200 M FeCl₃ are needed to react with an excess of Na₂S to produce 0.345 g of Fe₂S₃ if the percent yield for the reaction is 65.0%? 3 Na₂S(aq)+ 2 FeCl₃(aq)→ Fe₂S₃(s)+ 6 NaCl(aq) A)6.38 mL B)10.8 mL C)12.8 mL D)25.5 mL

Accepted Answer

The answer of How many milliliters of 0.200 M FeCl₃...

Question 7

Based on the activity series,which metal dissolves in hydrochloric acid to produce hydrogen gas,but does not react with steam or liquid water?
A)Mg
B)Hg
C)Sn
D)K

Accepted Answer

The answer of Based on the activity series,which metal dissolves...

Question 8

What is the oxidation number of the chromium atom in Li₂Cr₂O₄? A)-2 B)+2 C)+6 D)+7

Accepted Answer

In this compound, sulfur has an oxidation number of -2 and oxygen has an oxidation number of -2. Lithium has an oxidation number of +1. The total oxidation number for the compound must be zero, so we can calculate the oxidation number of chromium as follows:

(+1) + (-2) + 12(-2) + (-2) + x + 12(-2) + (-2) + 4(-2) = 0

Simplifying this equation gives:

x = +6

Therefore, the oxidation number of the chromium atom in the compound is +6.

Question 9

What is the oxidation number of the oxygen atom in O₂^2-? A)-2 B)-1 C)+1 D)+2

Accepted Answer

In most compounds, the oxidation number of oxygen is -2. However, there are some exceptions such as peroxides where its oxidation number is -1. In this compound, we can identify the peroxide group by the O-O bond. Therefore, the oxidation number of each oxygen atom is -1.

Question 10

What is the oxidation number of the sulfur atom in Li₂SO₄? A)-2 B)+2 C)+4 D)+6

Accepted Answer

The given chemical formula is for lithium sulfate, Li2SO4. In this compound, sulfur has an oxidation state of +6, as oxygen has a -2 oxidation state and lithium has a +1 oxidation state, balancing the overall charge to zero.

Question 11

In which compound is the oxidation state of oxygen not -2? A)MgO B)Na₂O C)K₂O₂ D)Al₂O₃

Accepted Answer

In potassium peroxide (K2O2), oxygen has an oxidation state of -1, unlike the usual -2 in most other compounds.

Question 12

Using the following portion of the activity series for oxidation half reactions Li(s)→ Li⁺(aq)+ e^- Al(s)→ Al³⁺(aq)+ 3e^- Fe(s)→ Fe²⁺(aq)+ 2e^- Pt(s)→ Pt²⁺(aq)+ 2e^- Determine which pairs of reactions will occur. A)Al(s)with Fe²⁺(aq)and Pt(s)with Li⁺(aq) B)Fe(s)with Al(s)and Al³⁺(aq)with Pt²⁺(aq) C)Fe(s)with Pt²⁺(aq)and Al(s)with Pt²⁺(aq) D)Li(s)with Al³⁺(aq)and Fe(s)with Al³⁺(aq)

Accepted Answer

The activity series indicates that a more reactive metal can displace a less reactive metal from its compound. Fe(s) can reduce Pt²⁺(aq) because Fe is more reactive than Pt. Similarly, Al(s) can reduce Pt²⁺(aq) because Al is more reactive than Pt.

Question 13

If 100.mL of 0.200 M Na₂SO₄ is added to 200.mL of 0.300 M NaCl,what is the concentration of Na⁺ ions in the final solution? Assume that the volumes are additive. A)0.267 M B)0.333 M C)0.500 M D)0.700 M

Accepted Answer

First, we need to find the moles of Na₂SO₄ and NaCl: moles of Na₂SO₄ = (0.200 M) x (0.100 L) = 0.020 mol moles of NaCl = (0.300 M) x (0.200 L) = 0.060 mol Next, we need to find the total volume of the solution: total volume = 100 mL + 200 mL = 0.300 L Using the mole ratio from the balanced equation of Na₂SO₄ + NaCl --> Na⁺ + NaClO4, we know that for every 1 mole of Na₂SO₄, we will get 1 mole of Na⁺. So, the concentration of Na⁺ in the final solution will be: concentration = moles of Na⁺ / total volume moles of Na⁺ = moles of Na₂SO₄ = 0.020 mol total volume = 0.300 L concentration = 0.020 mol / 0.300 L = 0.067 M However, we need to take into account that the NaCl also dissociates into Na+ and Cl- ions. NaCl is a strong electrolyte, which means it dissociates completely in water. Therefore, for every 1 mole of NaCl, we will get 1 mole of Na+ and 1 mole of Cl-. So, the total concentration of Na+ ions in the final solution will be: concentration of Na+ = moles of Na+ / total volume moles of Na+ = moles of Na⁺ + moles of NaCl moles of Na+ = 0.020 mol + 0.060 mol = 0.080 mol total volume = 0.300 L concentration of Na+ = 0.080 mol / 0.300 L = 0.267 M Therefore, the best choice is B) 0.333 M, since we need to find the concentration of Na⁺ ions, not Na+ ions.

Question 14

Coinage metals are metals that are not easily oxidized.Based on the activity series,which metal would be least desirable as a coinage metal?
A)Mn
B)Au
C)Ca
D)Co

Accepted Answer

The activity series arranges metals in order of their reactivity with oxygen, water, and acids. The least reactive metals are at the top of the activity series, while the most reactive metals are at the bottom. Ca (calcium) is much more reactive than the other options, and therefore would be the least desirable as a coinage metal because it would quickly tarnish and corrode. Mn, Au, and Co are all less reactive and more suitable for use in coins.

Question 15

Which species functions as the oxidizing agent in the following reduction-oxidation reaction? Zn(s)+ Ni²⁺(aq)→ Ni(s)+ Zn²⁺(aq) A)Ni(s) B)Ni²⁺(aq) C)Zn(s) D)Zn²⁺(aq)

Accepted Answer

In a redox reaction, the oxidizing agent is the species that gets reduced. In the given reaction, Ni^2+ (from Ni^2+ aq) gains electrons to form Ni(s), thus it is reduced and acts as the oxidizing agent.

Question 16

When 125 mL of 0.500 M AgNO₃ is added to 100.mL of 0.300 M NH₄Cl,how many grams of AgCl are formed? AgNO₃(aq)+ NH₄Cl(aq)→ AgCl(s)+ NH₄NO₃(aq) A)4.30 g B)8.96 g C)13.3 g D)25.8 g

Accepted Answer

First, we need to identify the limiting reactant. The moles of AgNO3 are calculated as $0.125 \, \text{L} \times 0.500 \, \text{M} = 0.0625 \, \text{moles}$, and the moles of NH4Cl are $0.100 \, \text{L} \times 0.300 \, \text{M} = 0.0300 \, \text{moles}$. Since the reaction is 1:1, NH4Cl is the limiting reactant. The moles of AgCl formed will be equal to the moles of NH4Cl, which is 0.0300 moles. The molar mass of AgCl is approximately 143.32 g/mol, so the mass of AgCl formed is $0.0300 \, \text{moles} \times 143.32 \, \text{g/mol} = 4.30 \, \text{g}$.

Question 17

What is the oxidation number of the sulfur atom in Cs₂SO₃? A)-2 B)+2 C)+4 D)+6

Accepted Answer

In Cs₂SO₃, cesium (Cs) has an oxidation number of +1, and oxygen (O) has an oxidation number of -2. The sum of oxidation numbers in a neutral compound is zero. Therefore, 2(+1) + S + 3(-2) = 0, solving for S gives +4.

Question 18

What is the oxidation number change for the chromium atom in the following unbalanced reduction half reaction? Cr₂O₇^2-(aq)+ H⁺(aq)→ Cr³⁺(aq)+ H₂O(l) A)-7 B)-3 C)+3 D)+6

Accepted Answer

The answer of What is the oxidation number change for...

Question 19

The unknown acid H₂X can be neutralized completely by NaOH according to the following equation: H₂X(aq)+ NaOH(aq)→ Na₂X + H₂O To completely neutralize this reaction,250 mL of 0.13 M NaOH were needed.How many moles of H₂X were present? A)0.033 B)0.065 C)0.016 D)3.8

Accepted Answer

To completely neutralize the reaction, the number of moles of NaOH used must be equal to the number of moles of H₂X present. The number of moles of NaOH used can be calculated using the formula: moles of NaOH = concentration of NaOH × volume of NaOH used. Substituting the given values into the formula, we get: moles of NaOH = 0.13 M × 0.250 L = 0.0325 moles. Therefore, the number of moles of H₂X present is also 0.0325 moles.

Question 20

In which compound is the oxidation state of hydrogen not +1? A)H₂S B)H₂O₂ C)KH D)KHSO₄

Accepted Answer

In compound KH, hydrogen has an oxidation state of -1, not +1 as it usually does in most compounds.

Quiz 4: Reactions in Aqueous Solutions

Using the following portion of the activity series for oxidation half reactions,determine which combination of reactants will result in a reaction. Ca(s) → Ca²⁺(aq) + 2 e^- Ag(s) → Ag⁺(aq) + e^-

Which element will react rapidly with aqueous H⁺ ions and also with liquid H₂O?

Which element will not react with liquid water or with aqueous H⁺ ions?

Using the following portion of the activity series for oxidation half reactions Mg(s) → Mg²⁺(aq) + 2e^- Co(s) → Co²⁺(aq) + 2e^- Cu(s) → Cu²⁺(aq) + 2e^- indicate which pairs of reactions will occur.

Which elementwill not react with liquid water but will react with aqueous H⁺ ions and steam?

How many milliliters of 0.200 M FeCl₃ are needed to react with an excess of Na₂S to produce 0.345 g of Fe₂S₃ if the percent yield for the reaction is 65.0%? 3 Na₂S(aq) + 2 FeCl₃(aq) → Fe₂S₃(s) + 6 NaCl(aq)

Based on the activity series,which metal dissolves in hydrochloric acid to produce hydrogen gas,but does not react with steam or liquid water?

What is the oxidation number of the chromium atom in Li₂Cr₂O₄?

What is the oxidation number of the oxygen atom in O₂^2-?

What is the oxidation number of the sulfur atom in Li₂SO₄?

In which compound is the oxidation state of oxygen not -2?

Using the following portion of the activity series for oxidation half reactions Li(s) → Li⁺(aq) + e^- Al(s) → Al³⁺(aq) + 3e^- Fe(s) → Fe²⁺(aq) + 2e^- Pt(s) → Pt²⁺(aq) + 2e^- Determine which pairs of reactions will occur.

If 100.mL of 0.200 M Na₂SO₄ is added to 200.mL of 0.300 M NaCl,what is the concentration of Na⁺ ions in the final solution? Assume that the volumes are additive.

Coinage metals are metals that are not easily oxidized.Based on the activity series,which metal would be least desirable as a coinage metal?

Which species functions as the oxidizing agent in the following reduction-oxidation reaction? Zn(s) + Ni²⁺(aq) → Ni(s) + Zn²⁺(aq)

When 125 mL of 0.500 M AgNO₃ is added to 100.mL of 0.300 M NH₄Cl,how many grams of AgCl are formed? AgNO₃(aq) + NH₄Cl(aq) → AgCl(s) + NH₄NO₃(aq)

What is the oxidation number of the sulfur atom in Cs₂SO₃?

What is the oxidation number change for the chromium atom in the following unbalanced reduction half reaction? Cr₂O₇^2-(aq) + H⁺(aq) → Cr³⁺(aq) + H₂O(l)

The unknown acid H₂X can be neutralized completely by NaOH according to the following equation: H₂X(aq) + NaOH(aq) → Na₂X + H₂O To completely neutralize this reaction,250 mL of 0.13 M NaOH were needed.How many moles of H₂X were present?

In which compound is the oxidation state of hydrogen not +1?

Quiz 4: Reactions in Aqueous Solutions

Using the following portion of the activity series for oxidation half reactions,determine which combination of reactants will result in a reaction. Ca(s) → Ca2+(aq) + 2 e- Ag(s) → Ag +(aq) + e-

Which element will react rapidly with aqueous H+ ions and also with liquid H2O?

Which element will not react with liquid water or with aqueous H+ ions?

Using the following portion of the activity series for oxidation half reactions Mg(s) → Mg2+(aq) + 2e- Co(s) → Co2+(aq) + 2e- Cu(s) → Cu2+(aq) + 2e- indicate which pairs of reactions will occur.

Which elementwill not react with liquid water but will react with aqueous H+ ions and steam?

How many milliliters of 0.200 M FeCl3 are needed to react with an excess of Na2S to produce 0.345 g of Fe2S3 if the percent yield for the reaction is 65.0%? 3 Na2S(aq) + 2 FeCl3(aq) → Fe2S3(s) + 6 NaCl(aq)

Based on the activity series,which metal dissolves in hydrochloric acid to produce hydrogen gas,but does not react with steam or liquid water?

What is the oxidation number of the chromium atom in Li2Cr2O4?

What is the oxidation number of the oxygen atom in O22-?

What is the oxidation number of the sulfur atom in Li2SO4?