Year 11 Chemistry Module 3: Reactive Chemistry Practice Questions

Question 6 ⭐⭐⭐🔥

In an experiment, 20.0g of lead (II) nitrate and 20.0g of potassium iodide were dissolved separately to form 250mL lead (II) nitrate solution and 250mL potassium iodide solution. The two solutions are then mixed together.

a) What is the maximum mass of lead (II) iodide that can be obtained from the experiment? (3 marks)

b) What is the concentration of potassium nitrate? (3 marks)

c) What is the net ionic equation for this reaction? (1 mark)

Predicting Reactions of Metals

Inquiry Question 2: How is the reactivity of various metals predicted?

Question 7 ⭐⭐

Complete the table below and then rank the metals based on their reactivity: (8 marks)

L2.1:Conduct practical investigations to compare the reactivity of a variety of metals in: Water, Dilute acid, Oxygen, Other metal ions in solution

Question 8 ⭐

Compare the similarities and differences between your results from your metal activity series practical from the theoretical metal activity series from secondary sources (2 marks). 

L2.2: construct a metal activity series using the data obtained from practical investigations and compare this series with that obtained from standard secondary-sourced information

Question 9 ⭐⭐⭐

a) Label the ionization energy, atomic radius and electronegativity patterns in the periodic table below: (3 marks)

Image sourced from Science Notes

Describe and explain the trends in metal activity on the periodic table in terms of their ionization energy, atomic radius and electronegativity. (6 marks)

L2.3: analyse patterns in metal activity on the periodic table and explain why they correlate with, for example: ionisation energy, atomic radius,  electronegativity

Question 10 ⭐⭐

Identify which is the reductant in the following reaction (3 marks): 

a) CH4(g)  + O2 (g) → H2O(l) + CO2 (g)

b) Fe3O4(aq) + 4H2 (g) → 3Fe(aq) + 4H2O (l) 

c) 4Al(s) +3O2(g) → 2Al2O3(s) 

L2.4: apply the definitions of oxidation and reduction in terms of electron transfer and oxidation numbers to a range of reduction and oxidation (redox) reactions

Question 11 ⭐⭐⭐🔥

a) Describe how you would measure and compare the reduction potential of galvanic half-cells containing copper and zinc. Include diagrams if necessary. (6 marks) 

L2.5: conduct investigations to measure and compare the reduction potential of galvanic half-cells

b) Calculate the cell potential using the standard reduction potential for each of the metal pairs (3 marks)

L2.6: Construct relevant half-equations and balanced overall equations to represent a range of redox reactions

Question 12 ⭐⭐

Write the half -equations and balanced overall redox equations for the reactions of the following metals:

a) Copper and iron 

b) Silver and lead 

c) Nickel and Magnesium 

L2.6: Construct relevant half-equations and balanced overall equations to represent a range of redox reactions

Question 13 ⭐

Identify the oxidant and reductant between the following metal pairs: (5 marks)

a) Magnesium and Barium 

b) Mercury and Iron 

c) Nickel and Silver 

d) Gold and Lead

e) Copper and Tin 

L2.7: predict the reaction of metals in solutions using the table of standard reduction potentials

Question 14 ⭐⭐

Explain how to predict whether a redox reaction is spontaneous or not using cell potentials (3 marks). 

L2.8: predict the spontaneity of redox reactions using the value of cell potentials (ACSCH079, ACSCH080

Rates of Reactions

Inquiry Question 3: What affects the rate of a chemical reaction?

Question 15 ⭐⭐

Explain how the following factors can influence the rate of reaction: (5 marks)

a) Increasing temperature on an endothermic reaction 

b) Decreasing temperature on an exothermic reaction 

c) Using a powdered reagent as opposed to a massive block of reagent

d) Increasing the concentration of reactant 

e) The addition of catalysts to an exothermic reaction 

L3.1: conduct a practical investigation, using appropriate tools (including digital technologies), to collect data, analyse and report on how the rate of a chemical reaction can be affected by a range of factors, including but not limited to: temperature, surface area of reactant(s), concentration of reactant(s), catalysts (ACSCH042)

Question 16 ⭐

A student grounded a block of reagent to powder to influence its rate of reaction. Explain how using a powdered reagent is more preferable to using a massive block of reagent (3 marks).

Question 17 ⭐⭐

Explain the role of a catalyst in altering the rate of reaction. (3 marks)

L3.1 Conduct a practical investigation, using appropriate tools (including digital technologies), to collect data, analyse and report on how the rate of a chemical reaction can be affected by a range of factors, including but not limited to: temperature, surface area of reactant(s), concentration of reactant(s), catalysts (ACSCH042). 

Question 18 ⭐⭐⭐

Explain how molecular orientation affects activation energy, with reference to the collision theory (4 marks). 

L3.2: investigate the role of activation energy, collisions and molecular orientation in collision theory

Question 19 ⭐⭐⭐

With reference to the collision theory, explain how temperature changes can alter reaction rate (4 marks).

L3.2: explain a change in reaction rate using collision theory

Question 20 ⭐⭐⭐🔥

Suppose we compare two reactions, one requiring the simultaneous collision of three molecules and the other requiring a collision between two molecules. From the standpoint of statistics, and all other factors being equal, which reaction should be faster? Explain your answer. (7 marks)

[Challenge Question]

Question 2

Question 3

💡TIP: start by filling in the “type of reaction” column in the order that they are listed in the syllabus dot point (below)

Question 4

Aboriginal and Torres Strait Islander peoples detoxify food by submerging them in water. For example, the cycad was consumed by many Indigenous Australian peoples even though it was highly toxic. The detoxification process for the cycad was to grind the kernels, which increased the surface area, and then submerge them in water, allowing the soluble toxins to be eluted in the water until equilibrium is established.

Question 5

💡TIP: start with any metals first, then carbons, oxygens and hydrogen last

Question 6

💡TIP: don’t forget to start with moles and finding the limiting reagent

Question 7

Question 8

Answers will vary for results obtained from practical.

Reactivity should be confirmed as follows:

Question 9

💡TIP: what makes elements reactive? Compare fluorine with carbon, a similar concept applies with the metals

Note: metals below potassium are not considered as they are unpredictable (can spontaneously explode)

The reactivity of a substance depends on its readiness to donate or accept an electron. Reactivity is determined by the ionisation energy, atomic radius and electronegativity of a substance. Ionisation energy is the amount of energy required to remove an electron. In terms of reactivity, the ionisation energy should be low for highly reactive atoms. The atomic radius determines how tightly the electrons are held in orbit; the larger the radius, the more likely the atom is to lose an electron. Electronegativity is the ability of an atom to attract electrons. Metals do not want to do this, hence for reactivity the electronegativity should be low.

Using this information, it can be seen that group 1 metals are the most reactive, followed by group 2 and then the remaining metals. This matches the metal reactivity series which states potassium as the most reactive. Referring to the periodic table, it is a group 1 metal (so ionisation energy and electronegativity are at their lowest) and has the largest atomic radius out of all atoms considered.

Question 10

Question 11

a) 

To measure the potential, a galvanic cell (consisting of two half-cells) should be set up, connected by a salt bridge and an external circuit to allow electron flow. The half-cells should have a copper or zinc electrode placed into a copper(II) sulfate or zinc sulfate solution respectively. By connecting the two electrodes to a voltmeter, the voltmeter can measure the potential difference between the two electrodes. This reading represents the overall cell potential, which can be used to compare the reduction potential using the standard reduction potentials for Cu²⁺ and Zn²⁺. A more positive reduction potential indicates reduction whilst a less positive (or negative) reduction potential value indicates oxidation.

b) 

Question 12

Question 13

Question 14

Spontaneity when considering cell potentials depends on the value of the electrical potential. If the electrical potential is negative, then it requires energy to kick-start the reaction. However, if the electrical potential of a redox reaction is positive then it is spontaneous, and the value correlates to the electrical energy released.

Question 15

a) Increasing the temperature of an endothermic reaction will increase the rate of reaction (as it is giving more energy to a system that absorbs energy)

b) Similarly, decreasing the temperature of an exothermic reaction will increase the rate of reaction (as more energy can be released from the reaction).

c) A powdered reagent has a greater surface area compared to a massive block of reagent and will therefore allow more successful collisions, increasing the rate of reactions.

d) Increasing the concentration of the reactant provides more of the substance to be reacted and will therefore increase the rate of reaction.

e) By adding a catalyst to an exothermic reaction the rate of reaction is increased as an alternate pathway is provided with a lower activation energy.

Question 16

A big block of the reagent will have a smaller surface area compared to the same mass of the reagent in powdered form. When the reagent is in powdered form, this increases the surface area, creating a “greater amount” of particles accessible by the other reagent. This creates more successful collisions which results in a faster rate of reaction.

Question 17

A catalyst is a substance that can be used as a stepping stone within the reaction. It provides an alternate reaction pathway with a lower activation energy that will therefore increase the rate of reaction, as the reaction is more spontaneous.

Question 18

Molecular orientation is crucial for successful collisions. The orientation determines which bonds are broken and then reformed. If the molecules have the wrong orientation upon collision, then no successful reaction will occur and the rate of reaction will slow. However, when molecules are correctly oriented, a greater number of successful collisions occur, increasing the rate of reaction.

Question 19

Collision theory states that for reactions to occur, particles must collide (in the correct orientation) and have enough energy (activation energy) in order to break and re-form new bonds. By increasing temperature, particles will have more energy and will therefore meet the activation energy more easily. They will also be moving faster, increasing the amount of successful collisions and thus, the rate of reaction. It follows that decreasing the temperature would achieve the opposite. 

Question 20

💡TIP: think about tossing coins and wanting to receive matching values (only heads or only tails), which is more likely, two coins or three?

Given that all reaction conditions are kept the same, the only difference is the number of molecules colliding. For successful collisions to occur and the reaction to proceed, molecules must already be colliding with the correct orientation. It follows that reactions where two particles are simultaneously colliding would proceed at a faster rate, compared to three simultaneous collisions. 

This can be modelled by comparing the collisions to the outcomes of tossing coins. When we toss two coins (representing the two particles), the outcome for each coin is either head (H) or tails (T). Successful collisions require the orientation to be correct, so HH or TT, and incorrect orientation would result in the results HT or TH. This gives a 50% chance of successful collisions.

However if we add a third coin (for the third particle), the outcomes with correct orientation are HHH or TTT. But the unsuccessful collisions due to incorrect orientation are HTH, HHT, TTH, THT, are double the amount compared to when we had two coins/particles. This gives a 33% chance of successful collisions.

Therefore, it can be seen that the reaction with two simultaneous collisions would proceed at a faster rate compared to the reaction with three simultaneous collisions.