Reversible reactions and equilibrium

Question 1

What are reversible reactions?

Answer 1

Reactions where products can react to produce the original reactants.

Question 2

What symbol is used for reversible reactions?

Answer 2

=

Question 3

In a reversible reaction, if one direction is exothermic, what is the other direction?

Answer 3

Endothermic.

Question 4

What happens when ammonium chloride is heated?

Answer 4

It turns from a white solid to a colourless gas.

Question 5

What is the equation for the heating of ammonium chloride?

Answer 5

NH4Cl(s) = NH3(g) + HCl(g)

Question 6

What is the method for heating ammonium chloride?

Answer 6

Add ammonium chloride to a boiling tube, loosely fit a mineral wool plug, warm the bottom with a Bunsen burner.

Question 7

What is produced when hydrated copper sulfate is heated?

Answer 7

Anhydrous copper sulfate and water.

Question 8

What is the equation for the heating of hydrated copper sulfate?

Answer 8

CuSO4·5H2O(s) = CuSO4(s) + 5H2O(l)

Question 9

What color change occurs when hydrated copper sulfate is heated?

Answer 9

Blue to white.

Question 10

What is the method for heating hydrated copper sulfate?

Answer 10

Add copper sulfate crystals to a boiling tube, gently heat, and observe the color change.

Question 11

True or False: The forwards reaction of heating hydrated copper sulfate is exothermic.

Answer 11

False.

Question 12

Fill in the blank: In reversible reactions, if the forwards reaction is endothermic, the backwards reaction is _______.

Answer 12

Exothermic.

Question 13

What happens when a few drops of water are added using a dropping pipette?

Answer 13

It turns white to blue.

Question 14

What type of reaction is heating in the context of dynamic equilibrium?

Answer 14

Endothermic.

Question 15

What is a dynamic equilibrium?

Answer 15

When the rate of the forward reaction is equal to the rate of the backward reaction.

Question 16

What occurs in a closed system that reaches dynamic equilibrium?

Answer 16

The concentrations of reactants and products stay the same.

Question 17

What does it indicate if the equilibrium lies on the left in a reaction A + B = C + D?

Answer 17

There is a greater concentration of A + B than C + D.

Question 18

What does it indicate if the equilibrium lies on the right in a reaction A + B = C + D?

Answer 18

There is a greater concentration of C + D than A + B.

Question 19

What happens to the equilibrium if it moves to the right?

Answer 19

More products are formed.

Question 20

What happens to the equilibrium if it moves to the left?

Answer 20

More reactants are formed.

Question 21

What is Le Chatelier’s Principle?

Answer 21

If you change the conditions of a reversible reaction in dynamic equilibrium, the equilibrium moves to minimise the effects of the change.

Question 22

How does increasing the temperature affect the position of equilibrium?

Answer 22

It moves the equilibrium in the endothermic direction to decrease the temperature.

Question 23

What happens to equilibrium when temperature decreases in an exothermic reaction?

Answer 23

Equilibrium moves in the exothermic direction

Question 24

How does increasing pressure affect equilibrium?

Answer 24

Moves equilibrium to the side with fewer gas molecules

Question 25

What is the effect of decreasing pressure on equilibrium?

Answer 25

Moves equilibrium to the side with more gas molecules

Question 26

What effect does increasing the concentration of a reactant have on equilibrium?

Answer 26

Moves equilibrium in the direction that decreases the excess amount added

Question 27

What occurs when the concentration of a substance in a reaction is decreased?

Answer 27

Moves equilibrium in the direction that increases the concentration of that substance

Question 28

In an exam, what should you state regarding equilibrium shifts?

Answer 28

The direction the equilibrium moves, the reason why, and which yield increases

Question 29

What color do cobalt ions exhibit when joined to water?

Answer 29

Pink

Question 30

What color do cobalt ions exhibit when joined to chloride ions?

Answer 30

Blue

Question 31

What color results from an equilibrium containing similar amounts of cobalt ions in water and chloride ions?

Answer 31

Violet

Question 32

What happens to the color of a cobalt solution when water is added?

Answer 32

Becomes pinker

Question 33

What color change occurs when hydrochloric acid is added to a cobalt solution?

Answer 33

Goes bluer

Question 34

What is the effect of adding acid to an equilibrium containing chromate complexes?

Answer 34

Goes the color of the ion with more hydrogen ions

Question 35

What happens to the color of chromate complexes when alkali is added?

Answer 35

Goes the color that has hydroxide on its side

Question 36

What is the role of a catalyst in a chemical reaction?

Answer 36

A catalyst speeds up a reaction by providing an alternative reaction pathway with a lower activation energy.

Question 37

Do catalysts affect the position of equilibrium in a reaction?

Answer 37

No, catalysts speed up both the forwards and backwards reaction by the same amount and do not change the position of the equilibrium.

Question 38

What are the chosen conditions for the Haber Process?

Answer 38

* High pressure - 200 atm * Relatively low temperature - 450 degrees C * An iron catalyst

Question 39

Why is high pressure (200 atm) used in the Haber Process?

Answer 39

Equilibrium shifts to the right as there are fewer gas molecules, increasing ammonia yield and speeding up the rate of reaction.

Question 40

What are the drawbacks of using very high pressure in the Haber Process?

Answer 40

* Too expensive to maintain safety * Too much energy required

Question 41

Why is a relatively low temperature (450 degrees C) used in the Haber Process?

Answer 41

Equilibrium shifts to the right in the exothermic direction to increase the temperature, thus increasing ammonia yield.

Question 42

What is a disadvantage of using a temperature that is too low in the Haber Process?

Answer 42

The rate of reaction is too slow.

Question 43

What type of catalyst is used in the Haber Process?

Answer 43

An iron catalyst.

Question 44

Why is iron used as a catalyst in the Haber Process?

Answer 44

Iron is cheap and readily available, even though it isn't the most effective catalyst.

Question 45

What are the raw materials used in the Haber Process?

Answer 45

* Nitrogen * Hydrogen

Question 46

Where is nitrogen sourced from for the Haber Process?

Answer 46

From the air.

Question 47

Fill in the blank: A catalyst does not affect the _______ of the reaction.

Answer 47

equilibrium

Question 48

True or False: The use of a catalyst in a reaction will change the yield of products.

Answer 48

False

Question 49

What is the primary source of hydrogen in the Haber process?

Answer 49

Reacting natural gas with steam to form hydrogen and carbon dioxide ## Footnote This reaction is essential for producing hydrogen needed in the process.

Question 50

What are the main conditions for the Haber process?

Answer 50

200 atm, 450°C, iron catalyst ## Footnote These conditions optimize the reaction between nitrogen and hydrogen to produce ammonia.

Question 51

List the main steps involved in the Haber process.

Answer 51

* Nitrogen and hydrogen are compressed * They react in the main reactor * Conditions: 450 degrees Celsius, 200 atm, iron catalyst * The product mixture is cooled * Ammonia liquifies in a cooling tank * Hydrogen and nitrogen are recycled as gas ## Footnote Each step is crucial for efficient ammonia production.

Question 52

Why is the Haber process important?

Answer 52

Ammonia is converted to ammonium compounds used in fertilizers ## Footnote Fertilizers are essential for enhancing crop yield.

Question 53

What do crops need for growth?

Answer 53

Nitrogen, phosphorus, and potassium ## Footnote These nutrients are critical for plant development.

Question 54

Define fertilizers.

Answer 54

A formulation - a mixture designed to produce a useful product with a specific composition ## Footnote Fertilizers improve soil fertility and crop production.

Question 55

How is potassium sourced for fertilizers?

Answer 55

* From potassium chloride * From potassium sulfate ## Footnote Both are mined directly and are soluble in water.

Question 56

What is the source of nitrogen for fertilizers?

Answer 56

The Haber process ## Footnote Ammonia produced is often converted into ammonium nitrate for better nitrogen content.

Question 57

What happens to ammonia in the presence of acids?

Answer 57

It forms an ammonium salt ## Footnote This reaction is utilized to produce ammonium compounds for fertilizers.

Question 58

Fill in the blank: Ammonia can be used directly but is usually converted into _______.

Answer 58

ammonium nitrate ## Footnote This conversion provides a higher nitrogen yield.

Question 59

What is the primary issue with phosphate rock as a nutrient source for plants?

Answer 59

It is insoluble and cannot be used by plants as nutrients. ## Footnote Phosphate rock must be processed to become available for plant use.

Question 60

What are the products of the reaction between phosphate rock and nitric acid?

Answer 60

Calcium nitrate and phosphoric acid. ## Footnote Phosphoric acid then reacts with ammonia to produce ammonium phosphates.

Question 61

What is formed when phosphate rock reacts with sulfuric acid?

Answer 61

Single superphosphate, a mixture of calcium sulfate and calcium phosphate.

Question 62

What is the main product of the reaction between phosphate rock and phosphoric acid?

Answer 62

Triple superphosphate, mainly calcium phosphate.

Question 63

What is the chemical equation for the reaction of ammonia with sulfuric acid?

Answer 63

2NH3 (aq) + H2SO4 (aq) → (NH4)2SO4 (aq)

Question 64

Describe the difference between industrial manufacture and lab preparation of fertilizers.

Answer 64

Industrial is larger, faster, continuous, higher concentrations, and very exothermic; lab is smaller, slower, batch process, lower concentrations, and safer.

Question 65

What equipment is typically used for the industrial manufacture of fertilizers?

Answer 65

Giant vats.

Question 66

What is a key characteristic of the industrial process for fertilizer production?

Answer 66

It is a continuous process as long as raw materials are provided.

Question 67

What method is used in the lab to produce fertilizers?

Answer 67

Titration followed by crystallization.

Question 68

Why is the lab method of fertilizer production not used in industry?

Answer 68

It is too slow.

Question 69

What type of reactants are used in the lab preparation of fertilizers?

Answer 69

Dilute forms of the two reactants.

Question 70

What must be done to apparatus in the lab before starting a new batch of fertilizers?

Answer 70

The apparatus must be cleaned.