AI Generated

Question 1

What occurs when chemical reactions do not go to completion?

Answer 1

Reversibility of chemical reactions

Reversible reactions can form products that can react with each other to reform the original reactants.

Question 2

What is the difference between static and dynamic equilibrium?

Answer 2

Static equilibrium is a static state in which the concentrations of reactants and products are constant and the rates of forward and reverse reaction are equal and zero. Dynamic equilibrium is a steady state in which the concentrations of reactants and products are constant and the rates of forward and reverse reaction are equal and non-zero.

Question 3

What is an example of a reversible reaction?

Answer 3

N2 (g) + 3H2 (g) ⇌ 2 NH3 (g)

Nitrogen and hydrogen can react with each other to form ammonia, which can also react with itself to reform into nitrogen and hydrogen.

Question 4

What happens in irreversible reactions?

Answer 4

Reactants convert to products and cannot revert back to reactants.

Question 5

What is the result of heating magnesium in a combustion reaction?

Answer 5

Formation of magnesium oxide (MgO)

The reaction is: 2 Mg (s) + O2 (g) → 2 MgO (s).

Question 6

What is formed when iron reacts with oxygen in a combustion reaction?

Answer 6

Iron(III) oxide (Fe2O3)

The reaction is: 4 Fe (s) + 3 O2 (g) → 2 Fe2O3 (s).

Question 7

Fill in the blank: In reversible reactions, the _______ reaction and reverse reaction occur simultaneously.

Answer 7

forward

Question 8

What happens when hydrated cobalt(II) chloride is heated?

Answer 8

It changes color from pink to sky blue

This indicates dehydration, and adding water back will return it to its original state.

Question 9

What does the term ‘irreversibility’ refer to in chemical reactions?

Answer 9

The inability of products to reform into reactants after the reaction has occurred.

Question 10

True or False: All chemical reactions are reversible.

Answer 10

False

Question 11

What signifies the formation of a complex in cobalt(II) chloride?

Answer 11

The change in color when water is added

Cobalt(II) chloride hexahydrate (CoCl2·6H2O) indicates hydration.

Question 12

What is the result of heating CoCl2 · 6H2O?

Answer 12

It removes 4 molecules of water to form CoCl2 · 2H2O and further heating removes the other 2 water molecules to form CoCl2 (s)

This reaction demonstrates the dehydration of cobalt(II) chloride hexahydrate.

Question 13

What happens in the reverse reaction of CoCl2?

Answer 13

Adding 2 molecules of deionized water and 4 molecules turns it back into the original pink CoCl2 · 6H2O

This illustrates the reversibility of the hydration reaction.

Question 14

Write the net ionic equation for the reaction of iron(III) nitrate and potassium thiocyanate.

Answer 14

Fe^3+ (aq) + SCN^- (aq) → FeSCN^2+ (aq)

This equation excludes spectator ions and focuses on the ions that undergo change.

Question 15

What is the definition of a net ionic equation?

Answer 15

Equations that show only the species that undergo change, excluding ‘spectator ions’

Net ionic equations are applicable only in aqueous solutions.

Question 16

What does true dynamic equilibrium mean?

Answer 16

Dynamic Equilibrium is a steady state in which the concentrations of reactants and products are constant and the rates of forward and reverse reactions are equal and non zero.

i.e. both the forward and reverse reaction are occurring simultaneously.

Question 17

Fill in the blank: At equilibrium, the concentrations of substances ______.

Answer 17

remain constant

Question 18

True or False: In a dynamic equilibrium, the rates of the forward and reverse reactions are not equal.

Answer 18

False

Question 19

What is the color of the product formed from the reaction of iron(III) nitrate and potassium thiocyanate?

Answer 19

Blood-red

This color change indicates the formation of the complex ion FeSCN^2+.

Question 20

What indicates that a chemical reaction is reversible?

Answer 20

The ability to convert reactants back into products continually

This can be observed through the changes in color of cobalt(II) chloride during hydration and dehydration.

Question 21

What is the significance of ‘spectator ions’ in net ionic equations?

Answer 21

They remain unchanged during the reaction

Spectator ions do not participate in the chemical change and are excluded from the net ionic equation.

Question 22

What is a true dynamic equilibrium?

Answer 22

A state where reactants form products and products form reactants simultaneously

This equilibrium means that the reaction will never reach 100% completion.

Question 23

What occurs at the point of dynamic equilibrium in a reaction?

Answer 23

The rate at which products and reactants are being made becomes equal

This means both reactants and products are always present.

Question 24

In a dynamic equilibrium, what can be observed in a reaction involving multiple substances?

Answer 24

A mix of colors, (including pale-orange, colorless, and blood-red in the reaction of iron (III) nitrate and potassium thiocyanate)

This indicates that all three substances are always present in the reaction.

Question 25

Define a closed system in the context of chemical reactions.

Answer 25

A system where no matter is transferred, only energy is exchanged ## Footnote This system contains a constant number of particles.

Question 26

What is the difference between a closed system and an open system?

Answer 26

Closed systems only exchange energy, while open systems exchange both matter and energy ## Footnote Open systems allow for constant input and output of materials.

Question 27

What do static and dynamic equilibria require?

Answer 27

Closed systems ## Footnote This is essential for maintaining equilibrium conditions.

Question 28

What happens in an open system regarding concentrations of substances?

Answer 28

Concentrations are always changing due to the constant input and output of matter ## Footnote This prevents the formation of a steady state.

Question 29

True or False: In a closed system, matter can be transferred in or out.

Answer 29

False ## Footnote Closed systems do not allow matter transfer, only energy exchange.

Question 30

Fill in the blank: The universe is defined as _______.

Answer 30

system + surroundings ## Footnote This includes all matter and energy involved in a chemical reaction.

Question 31

What is an isolated system?

Answer 31

A system that does not permit matter or energy to transfer.

Question 32

Define equilibrium.

Answer 32

A state where concentrations of reactants and products are constant and rates of forward and reverse reactions are equal.

Question 33

What is static equilibrium?

Answer 33

A static state where concentrations of reactants/products are constant and rates of forward and reverse reactions are zero.

Question 34

What characterizes dynamic equilibrium?

Answer 34

Concentrations of reactants/products are constant and rates of forward and reverse reactions are non-zero.

Question 35

What is the difference between reversible and non-reversible reactions?

Answer 35

Reversible reactions never reach completion, while non-reversible reactions reach completion.

Question 36

Provide an example of a reversible reaction.

Answer 36

N₂(g) + 3H₂(g) ⇌ 2NH₃(g)

Question 37

Provide an example of a non-reversible reaction.

Answer 37

C(graphite) → C(diamond)

Question 38

What is the first step in modeling dynamic equilibrium?

Answer 38

Place 50 marbles in container A (reactants) and 50 marbles in container B (products).

Question 39

What action is taken in the second step of modeling dynamic equilibrium?

Answer 39

Transfer half the marbles from A to B (forward reaction) and one quarter from B back to A (reverse reaction).

Question 40

What is the point of repeating the marble transfer process in the dynamic equilibrium model?

Answer 40

To model dynamic equilibrium - constant concentrations of reactants/products and equal rates of forward and reverse reactions.

Question 41

List some limitations of the dynamic equilibrium model.

Answer 41

* Does not show constant exchange of matter * Does not show collisions that occur in reality * No energy change is shown.