Crystal Lake Central Invitational - IL — Chemistry Lab

Chemistry Lab · Division C · Crystal Lake Central Invitational - IL · 2026

43 questions · 43 points · 50 min· 8 questions from the original omitted

Original test source

Part 1: Chemical Reactions / Stoichiometry

Question 2

1 pt

When the equation Mg + HCl → MgCl₂ + H₂ is balanced, what is the coefficient for HCl?

A. 1B. 2C. 3D. 4

Question 3

1 pt

The equation 2 C₃H₇OH + 9 O₂ → 6 CO₂ + 8 H₂O is an example of which type of reaction?

A. combustionB. combinationC. double replacementD. decomposition

Question 4

1 pt

A double replacement takes place when aqueous K₂SO₄ reacts with aqueous Pb(NO₃)₂. You should expect one of the products of the reaction to be:

A. KNO₃B. NaPbC. Pb(SO₄)₂D. CNO₃

Question 6

1 pt

When the equation Fe + O₂ → Fe₂O₃ is balanced, what is the coefficient for Fe₂O₃?

A. 1B. 2C. 3D. 4

Question 7

1 pt

The reaction in question 6 is an example of a:

A. combination reactionB. decomposition reactionC. single replacement reactionD. double replacement reaction

Question 8

1 pt

Which binary compound decomposes to form K + I₂?

A. KI₂B. KIC. K₂ID. none of these

Question 9

1 pt

In order for the reaction Cu + 2 AgNO₃ → Cu(NO₃)₂ + 2 Ag to occur, which of the following must be true?

A. Cu must be above Ag in the activity seriesB. Ag must be above Cu in the activity seriesC. Cu must be above H in the activity seriesD. Ag must be above H in the activity series

Question 11

1 pt

The complete combustion of octane (C₈H₁₈) would:

A. Require 25 O₂B. Produce 16 CO₂C. Produce 18 H₂OD. All of these

Question 12

1 pt

If butane (C₄H₁₀) undergoes complete combustion:

A. 8 CO₂ is one productB. 8 CO is one productC. 9 O₂ is one reactantD. 10 O₂ is one reactant

Question 13

1 pt

When H₂SO₄ and NaOH react by double replacement,

A. 2H₂SO₄ are requiredB. 1 NaOH is requiredC. 2 H₂O are producedD. 2H₂SO₄ are produced

Question 14

1 pt

Based on the activity series, the reaction that is most likely to occur from among the following is:

A. Cu + HCl →B. Zn + HNO₃ →C. Pb + Na₂SO₄ →D. Ni + Ba(NO₃)₂ →

Question 15

1 pt

The spectator ions in the reaction ZnCl₂(aq) + LiOH(aq) → LiCl(aq) + Zn(OH)₂(s) are:

A. Zn²⁺ and OH⁻B. Zn²⁺ and Cl⁻C. Li⁺ and OH⁻D. Li⁺ and Cl⁻

Question 16

1 pt

When the equation Fe + O₂ → Fe₂O₃ is balanced, the coefficient for O₂ is:

A. 4B. 3C. 2D. 1

Question 17

1 pt

The equation H₃PO₄ + 3 KOH → K₃PO₄ + 3 H₂O is an example of which kind of reaction?

A. double replacementB. combinationC. decompositionD. single replacement

Question 18

1 pt

In a double replacement reaction:

A. The reactants are usually a metal and a nonmetalB. The reactants are generally two ionic compounds in aqueous solutionC. One of the reactants is often waterD. Energy in the form of heat or light is always produced

Question 21

1 pt

When a precipitation reaction occurs, the ions that do NOT form the precipitate

PassageFor questions 22–23

For questions 22 & 23 use the balanced equation provided.

2HCl + Ca(OH)₂ → 2H₂O + CaCl₂

Molar Masses: 36.46 g, 74.10 g, 18.02 g, 110.98 g

Question 22

1 pt

45 mL of 3.5 M hydrochloric acid solution reacts with 35 mL of 1.85 M calcium hydroxide solution. What is the limiting reactant?

A. HClB. Ca(OH)₂C. CaCl₂D. None of these

Question 23

1 pt

45 mL of 3.5 M hydrochloric acid solution reacts with 35 mL of 1.85 M calcium hydroxide solution. What mass of water will be produced?

A. 2.33 g H₂OB. 0.741 g H₂OC. 14.11 g H₂OD. 8.55 g H₂O

PassageFor question 25

For question 25 use the balanced equation provided.

2NaClO₃ → 2NaCl + 3O₂

Molar Masses: 106.44g 58.44g 32g

Question 25

1 pt

If 145g of sodium chlorate was decomposed what volume of O₂ at 112°C and 1.7atm will be produced?

A. 12L O₂B. 23L O₂C. 56L O₂D. 38L O₂

Part 2: Kinetics

Question 1

1 pt

The energy diagram for the reaction X + Y → Z is shown above. The addition of a catalyst to this reaction would cause a change in which of the indicated energy differences?

Question 2

1 pt

A homogeneous liquid reaction mixture is often heated to increase the rate of reaction. This is best explained by the fact that raising the temperature

A. increases the heat of reaction.B. decreases the energy of activation.C. increases the vapor pressure of the liquidD. increases the average kinetic energy of the reactants.

Question 3

1 pt

For the reaction, 2A + B → C which relationship is correct? (A negative sign implies the substance is being used up)

A. The rate of C is +4.0M/s when the rate of A is 4.0M/s.B. The rate of C is +4.0M/s when the rate of A is -4.0M/s.C. The rate of C is +4.0M/s when the rate of A is -8.0M/s.D. The rate of C is +8.0M/s when the rate of A is -4.0M/s.

Question 4

1 pt

This exothermic reaction is catalyzed by MnO₂(s).

2H₂O₂(aq) → 2H₂O(l) + O₂(g)

Which of the following will further increase the rate of this reaction?

Raising the temperature
Increasing the surface area of MnO₂(s)

A. 1 onlyB. 2 onlyC. Both 1 and 2D. Neither 1 and 2

Question 5

1 pt

Which of the following is constant for different reactant concentrations in a first-order reaction?

A. The time required for the concentration of reactants to drop below 0.001 M.B. The time required for one-half of reactants to disappear.C. The rate of disappearance of reactants in mol∙L⁻¹∙time⁻¹.D. The rate of formation of products in mol∙L⁻¹∙time⁻¹.

Question 6

1 pt

The rates of which reactions are increased when the temperature is raised?

I endothermic reactions II exothermic reactions

A. I onlyB. II onlyC. Both I and IID. Neither I nor II

Question 8

1 pt

For the reaction 2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l), the rate of disappearance of C₂H₆(g)

A. equals the rate of disappearance of O₂(g).B. is seven times the rate of disappearance of O₂(g).C. is twice the rate of appearance of CO₂(g).D. is one-third the rate of appearance of H₂O(l).

Question 9

1 pt

For the reaction A + B → C, the rate law is: Rate = k[A]². Which change(s) will increase the rate of the reaction?

I. Increasing the concentration of A II. Increasing the concentration of B

A. I onlyB. II onlyC. Both I and IID. Neither I nor II

Question 10

1 pt

Which does NOT change with time for a first-order reaction?

A. the amount of reactant that disappears in each half-lifeB. the concentration of the reactantC. the length of each half-lifeD. the rate of the reaction

Question 11

1 pt

Which of the following conditions must be met in a collision for a reaction to occur:

Appropriate Orientation
Appropriate Energy
Appropriate Pressure

A. I onlyB. III onlyC. I and II onlyD. I, II and III

Question 12

1 pt

A 1st order reaction has its reactant decrease from 8M to 0.5M over 16 days. What is the length of a single half-life?

A. 1 dayB. 2 daysC. 4 daysD. 6 days

Question 13

1 pt

Relatively slow rates of chemical reaction are associated with which of the following?

Question 14

1 pt

Step 1: Ce⁴⁺ + Mn²⁺ → Ce³⁺ + Mn³⁺

Step 2: Ce⁴⁺ + Mn³⁺ → Ce³⁺ + Mn⁴⁺

Step 3: Mn⁴⁺ + Tl⁺ → Tl³⁺ + Mn²⁺

The proposed steps for a catalyzed reaction between Ce⁴⁺ and Tl⁺ are represented above. The products of the overall catalyzed reaction are

PassageFor questions 15–16

For questions 15-16 use the following reaction mechanism

O₃(g) + NO(g) → NO₂(g) + O₂(g) slow

NO₂(g) + O(g) → NO(g) + O₂(g) fast

O₃(g) + O(g) → 2O₂(g) overall reaction

Question 15

1 pt

Which species is a catalyst?

A. NO(g)B. NO₂(g)C. O₃(g)D. O₂(g)

Question 16

1 pt

Which species is an intermediate?

A. NO(g)B. NO₂(g)C. O₃(g)D. O₂(g)

Question 17

1 pt

Which of the following is true of catalysts?

A. Catalysts can slow down a reaction by adsorping.B. Catalysts can migrate in the reaction system, but this behavior is limited to enzymes.C. Catalysts do not get used up in a reaction, and speed up a reaction by reducing activation energy.D. Catalysts known as inhibitors slow down chemical reaction by reducing the activation energy.

Question 18

1 pt

Which of step of the following 3 step reaction mechanism is the rate-determining step?

A. 1B. 2C. 3D. None of the above

Question 20

1 pt

Magnesium metal reacts with hydrochloric acid to form magnesium chloride and hydrogen gas. Which set of conditions will raise the rate of the reaction between the metal and acid by the greatest magnitude?

A. reacting a magnesium metal cube and 6.0M HCl solutionB. reacting a magnesium metal cube and 1.0M HCl solutionC. reacting magnesium metal dust and 6.0M HCl solutionD. reacting magnesium metal dust and 1.0M HCl solution

Question 21

1 pt

The purple-pink color of potassium permanganate disappears gradually as it reacts with a mixture of oxalic acid and sulfuric acid. One test tube containing the reaction mixture is placed in hot water, a second one is placed in cold water, and a third one is placed in water at ambient or room temperature. The times taken for the color of potassium permanganate to disappear are 10 minutes, 3 minutes, and 2 minutes, in no particular order. Which set shows the correct match of the temperature of water and the time taken for the color to disappear?

A. hot water = 10 mins; cold water = 2 mins; room temperature water = 3 minsB. hot water = 3 mins; cold water = 10 mins; room temperature water = 2 minsC. hot water = 3 mins; cold water = 2 mins; room temperature water = 10 minsD. hot water = 2 mins; cold water = 10 mins; room temperature water = 3 Mins

Question 23

1 pt

Energy is required to partially break the bonds in the sugar molecule. The sugar molecule forms an activated state before the final products are formed. A student who observed the activity modeled the energy change during the reaction using the energy diagram shown.

Which letter represents the activation energy of the reaction?

A. AB. BC. CD. D

Question 24

1 pt · select all that apply

Which statements about the activation energy during a chemical reaction are true? Select all that apply.

A. It is equal to the energy of the products.B. It is higher than the energy of the reactants.C. It is equal to the energy of the activated complex.D. It is less than the energy of the activated complex.

Question 25

1 pt

A change in concentration over time is the

A. reaction rateB. transition stateC. activated complexD. intermediate product

Part 1: Chemical Reactions / Stoichiometry

Question 2

Question 3

Question 4

Question 6

Question 7

Question 8

Question 9

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 19

Question 20

Question 21

Question 22

Question 23

Question 25

Part 2: Kinetics

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 8

Question 9

Question 10

Question 11

Question 12

Question 13

Question 14

Question 15

Question 16

Question 17

Question 18

Question 20

Question 21

Question 23

Question 24

Question 25