Reversible reactions and equilibrium Flashcards
What are reversible reactions?
Reactions where products can react to produce the original reactants.
What symbol is used for reversible reactions?
=
In a reversible reaction, if one direction is exothermic, what is the other direction?
Endothermic.
What happens when ammonium chloride is heated?
It turns from a white solid to a colourless gas.
What is the equation for the heating of ammonium chloride?
NH4Cl(s) = NH3(g) + HCl(g)
What is the method for heating ammonium chloride?
Add ammonium chloride to a boiling tube, loosely fit a mineral wool plug, warm the bottom with a Bunsen burner.
What is produced when hydrated copper sulfate is heated?
Anhydrous copper sulfate and water.
What is the equation for the heating of hydrated copper sulfate?
CuSO4·5H2O(s) = CuSO4(s) + 5H2O(l)
What color change occurs when hydrated copper sulfate is heated?
Blue to white.
What is the method for heating hydrated copper sulfate?
Add copper sulfate crystals to a boiling tube, gently heat, and observe the color change.
True or False: The forwards reaction of heating hydrated copper sulfate is exothermic.
False.
Fill in the blank: In reversible reactions, if the forwards reaction is endothermic, the backwards reaction is _______.
Exothermic.
What happens when a few drops of water are added using a dropping pipette?
It turns white to blue.
What type of reaction is heating in the context of dynamic equilibrium?
Endothermic.
What is a dynamic equilibrium?
When the rate of the forward reaction is equal to the rate of the backward reaction.
What occurs in a closed system that reaches dynamic equilibrium?
The concentrations of reactants and products stay the same.
What does it indicate if the equilibrium lies on the left in a reaction A + B = C + D?
There is a greater concentration of A + B than C + D.
What does it indicate if the equilibrium lies on the right in a reaction A + B = C + D?
There is a greater concentration of C + D than A + B.
What happens to the equilibrium if it moves to the right?
More products are formed.
What happens to the equilibrium if it moves to the left?
More reactants are formed.
What is Le Chatelier’s Principle?
If you change the conditions of a reversible reaction in dynamic equilibrium, the equilibrium moves to minimise the effects of the change.
How does increasing the temperature affect the position of equilibrium?
It moves the equilibrium in the endothermic direction to decrease the temperature.
What happens to equilibrium when temperature decreases in an exothermic reaction?
Equilibrium moves in the exothermic direction
How does increasing pressure affect equilibrium?
Moves equilibrium to the side with fewer gas molecules
What is the effect of decreasing pressure on equilibrium?
Moves equilibrium to the side with more gas molecules
What effect does increasing the concentration of a reactant have on equilibrium?
Moves equilibrium in the direction that decreases the excess amount added
What occurs when the concentration of a substance in a reaction is decreased?
Moves equilibrium in the direction that increases the concentration of that substance
In an exam, what should you state regarding equilibrium shifts?
The direction the equilibrium moves, the reason why, and which yield increases
What color do cobalt ions exhibit when joined to water?
Pink
What color do cobalt ions exhibit when joined to chloride ions?
Blue
What color results from an equilibrium containing similar amounts of cobalt ions in water and chloride ions?
Violet
What happens to the color of a cobalt solution when water is added?
Becomes pinker
What color change occurs when hydrochloric acid is added to a cobalt solution?
Goes bluer
What is the effect of adding acid to an equilibrium containing chromate complexes?
Goes the color of the ion with more hydrogen ions
What happens to the color of chromate complexes when alkali is added?
Goes the color that has hydroxide on its side
What is the role of a catalyst in a chemical reaction?
A catalyst speeds up a reaction by providing an alternative reaction pathway with a lower activation energy.
Do catalysts affect the position of equilibrium in a reaction?
No, catalysts speed up both the forwards and backwards reaction by the same amount and do not change the position of the equilibrium.
What are the chosen conditions for the Haber Process?
- High pressure - 200 atm
- Relatively low temperature - 450 degrees C
- An iron catalyst
Why is high pressure (200 atm) used in the Haber Process?
Equilibrium shifts to the right as there are fewer gas molecules, increasing ammonia yield and speeding up the rate of reaction.
What are the drawbacks of using very high pressure in the Haber Process?
- Too expensive to maintain safety
- Too much energy required
Why is a relatively low temperature (450 degrees C) used in the Haber Process?
Equilibrium shifts to the right in the exothermic direction to increase the temperature, thus increasing ammonia yield.
What is a disadvantage of using a temperature that is too low in the Haber Process?
The rate of reaction is too slow.
What type of catalyst is used in the Haber Process?
An iron catalyst.
Why is iron used as a catalyst in the Haber Process?
Iron is cheap and readily available, even though it isn’t the most effective catalyst.
What are the raw materials used in the Haber Process?
- Nitrogen
- Hydrogen
Where is nitrogen sourced from for the Haber Process?
From the air.
Fill in the blank: A catalyst does not affect the _______ of the reaction.
equilibrium
True or False: The use of a catalyst in a reaction will change the yield of products.
False
What is the primary source of hydrogen in the Haber process?
Reacting natural gas with steam to form hydrogen and carbon dioxide
This reaction is essential for producing hydrogen needed in the process.
What are the main conditions for the Haber process?
200 atm, 450°C, iron catalyst
These conditions optimize the reaction between nitrogen and hydrogen to produce ammonia.
List the main steps involved in the Haber process.
- 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
Each step is crucial for efficient ammonia production.
Why is the Haber process important?
Ammonia is converted to ammonium compounds used in fertilizers
Fertilizers are essential for enhancing crop yield.
What do crops need for growth?
Nitrogen, phosphorus, and potassium
These nutrients are critical for plant development.
Define fertilizers.
A formulation - a mixture designed to produce a useful product with a specific composition
Fertilizers improve soil fertility and crop production.
How is potassium sourced for fertilizers?
- From potassium chloride
- From potassium sulfate
Both are mined directly and are soluble in water.
What is the source of nitrogen for fertilizers?
The Haber process
Ammonia produced is often converted into ammonium nitrate for better nitrogen content.
What happens to ammonia in the presence of acids?
It forms an ammonium salt
This reaction is utilized to produce ammonium compounds for fertilizers.
Fill in the blank: Ammonia can be used directly but is usually converted into _______.
ammonium nitrate
This conversion provides a higher nitrogen yield.
What is the primary issue with phosphate rock as a nutrient source for plants?
It is insoluble and cannot be used by plants as nutrients.
Phosphate rock must be processed to become available for plant use.
What are the products of the reaction between phosphate rock and nitric acid?
Calcium nitrate and phosphoric acid.
Phosphoric acid then reacts with ammonia to produce ammonium phosphates.
What is formed when phosphate rock reacts with sulfuric acid?
Single superphosphate, a mixture of calcium sulfate and calcium phosphate.
What is the main product of the reaction between phosphate rock and phosphoric acid?
Triple superphosphate, mainly calcium phosphate.
What is the chemical equation for the reaction of ammonia with sulfuric acid?
2NH3 (aq) + H2SO4 (aq) → (NH4)2SO4 (aq)
Describe the difference between industrial manufacture and lab preparation of fertilizers.
Industrial is larger, faster, continuous, higher concentrations, and very exothermic; lab is smaller, slower, batch process, lower concentrations, and safer.
What equipment is typically used for the industrial manufacture of fertilizers?
Giant vats.
What is a key characteristic of the industrial process for fertilizer production?
It is a continuous process as long as raw materials are provided.
What method is used in the lab to produce fertilizers?
Titration followed by crystallization.
Why is the lab method of fertilizer production not used in industry?
It is too slow.
What type of reactants are used in the lab preparation of fertilizers?
Dilute forms of the two reactants.
What must be done to apparatus in the lab before starting a new batch of fertilizers?
The apparatus must be cleaned.
