The Rate and Extent of Chemical Change Flashcards
If you want to measure the rate of a reaction you can measure how fast one of the __________ is formed. What one word completes this sentence?
products
If you want to measure the rate of a reaction you can measure how fast one of the __________ is used up. What one word completes this sentence?
reactants
A reaction between two particles cannot happen unless the particles have enough __________ when they collide. What is the missing word?
energy
If you want to increase the rate of a reaction, should you increase, decrease or make no change to the pressure?
increase
True or false? Decreasing the temperature increases the number of collisions between reacting particles.
false
Magnesium reacts with acid to give a salt and hydrogen. Will this reaction happen faster using magnesium ribbon or magnesium powder?
magnesium powder
Magnesium reacts with acid to give a salt and hydrogen. Why does the reaction happen faster because you use magnesium powder?
Powdered solids have a faster rate of reaction because they have a larger surface area.
For a reaction to happen the reacting particles must successfully __________ with one another. What word completes this sentence?
bond
True or false? If the same reaction is carried out twice, once at high pressure and once at low pressure, the reaction at low pressure will have a shorter reaction time.
false
At ____ ______, there are more particles per unit volume.
higher pressures
At higher pressures, there are more ________ per unit volume.
particles
the amount of energy needed for the reaction to occur
activation energy
Does increasing the surface area of a solid reactant increase, decrease or have no effect on the frequency of collisions between the reacting particles?
increase
True or false? Increasing the temperature rarely has an effect on the speed of the reacting particles.
false
Does decreasing the temperature increase the rate of a reaction?
no
Why does increasing the concentration of reactants increases the reaction rate?
the reactant particles are more crowded so they collide more often
What word is used to describe how fast or slow a reaction is?
rate
True or false? Catalysts do not change the rates of chemical reactions.
false
Does a catalyst increase, decrease or have no effect on the rate of a reaction?
increase
An iron catalyst is used to lower the activation energy of a reaction. What effect will this have on the overall energy change of the reaction?
stay the same
Catalysts work by lowering the __________ __________. What two words complete the sentence?
activation energy
True or false? Different reactions require different catalysts.
true
What name is given to any chemical which increases the rate of a chemical reaction?
catalyst
True or false? Catalysts are important in industrial processes because they reduce costs.
true
Increasing the temperature means that the particles have more energy and so collide __________.
more frequently
True or false? Endothermic reactions cannot be catalysed.
false
True or False? Every reaction can potentially be catalysed.
true
True or false? A catalyst provides a different pathway for a reaction with a higher activation energy for a reaction.
false
The number of collisions between the particles of hydrogen and nitrogen is increased by using high pressure and __________.
temperature
True or false? Only a small amount of a catalyst is needed to catalyse large amounts of reactants.
true
Will decreasing the pressure increase, decrease or have no effect on the number of collisions between the particles of two reacting gases?
decrease
How does using a catalyst change the activation energy?
decreases
What is the name of a biological catalyst?
enzyme
What name is given to a substance that changes the rate of a chemical reaction without being used up in the reaction?
catalyst
Will increasing the concentration of reactants increase or decrease the rate of a reaction?
increase the rate of reaction
True or false? Changing the temperature will always change the position of the equilibrium for a reversible reaction.
true
When products are being made as quickly as reactants, the reaction is said to have reached… what?
equilibrium
Equilibrium is reached when the forward reaction happens at exactly the same __________ as the backward reaction. What one word completes this sentence?
rate or speed
If the temperature of a reversible reaction is raised, the yield from the exothermic reaction… what?
decreased
True or false? Only reversible reactions in open systems can reach equilibrium.
false
True or False? Equilibrium can only be reached in a closed system.
true
True or false? A reversible reaction is always exothermic in one direction and endothermic in the other.
true
We can use Le Chatelier’s Principle to predict what will happen to a reversible reaction that is at __________ if we change its temperature, concentration or pressure. What word completes the sentence?
equilibrium
This symbol equation shows the production of ammonia: N2 (g) + 3H2 (g) ⇌ 2NH3 (g). Which direction will the equilibrium position shift if the pressure is increased?
to the right
For gaseous reactions at equilibrium a decrease in pressure causes the equilibrium position to shift towards the side with the __________ number of molecules. What word is missing from this sentence?
larger
If the temperature is raised, the yield from the endothermic reaction… what?
increases
A system is at equilibrium. If its temperature is increased, the relative amount of products will __________ for the endothermic reaction. What is missing from this sentence?
increase
A system is at equilibrium. If its temperature is decreased, the relative amount of products will __________ for the exothermic reaction. What is missing from this sentence?
increases
Here is the symbol equation for the production of ammonia: N2 (g) + __H2 (g) ⇌ 2NH3 (g). What number should be put in the space before H2 (g) to balance this symbol equation?
3
True or false? Changing the pressure has no effect on a reversible reaction unless one of the products or reactants is a gas.
true
The symbol equation for manufacturing ethanol is: H2O (g) + C2H4 (g) ⇌ C2H5OH (g) The manufacture of ethanol is exothermic. What would happen to the yield of ethanol if the temperature of the reaction is increased?
it would decrease
For gaseous reactions at equilibrium an increase in pressure causes the equilibrium position to shift towards the side with the __________ number of molecules. What word is missing from this sentence?
smaller
True or false? An equilibrium position always responds to oppose any change in the reaction conditions.
true
Here is the symbol equation for the production of ammonia: N2 (g) + 3H2 (g) ⇌ 2NH3 (g). What does the state symbol (g) mean?
gas
A reversible reaction is always exothermic in one direction and endothermic in the other. If the temperature is lowered, this will favour the __________ reaction. Which word completes the sentence?
exothermic
True or false? Changing the pressure will always change the position of the equilibrium for a reversible reaction.
false
Here is the equation for manufacturing ethanol: H2O (g) + C2H4 (g) ⇌ C2H5OH (g) The manufacture of ethanol is exothermic. Where would the position of the equilibrium move if the temperature of the reaction increased?
left
This symbol equation shows the production of ammonia: N2 (g) + 3H2 (g) ⇌ 2NH3 (g). Where would the direction of the equilibrium shift if the pressure decreased?
to the left
The symbol equation for manufacturing ethanol is: H2O (g) + C2H4 (g) → C2H5OH (g) Increasing the temperature lowers the yield of ethanol because the forward reaction is __________. What is the missing word in this sentence?
exothermic
If a change occurs when a system is at equilibrium, the equilibrium position shifts in order to counteract the change. This is known as __________’s Principle. What name completes the sentence?
Le Chatelier
the rate of a chemical reaction is how fast the _________ are changed into _________.
reactants are changed into products
example of slow reactions
iron rusting
example of moderate speed reaction
metal magnesium react with an acid to produce bubbles
example of fastest reaction
fireworks exploding
steeper the line on the graph the ________ the rate of reaction.
faster
why does the line on the line graph become less steep over time
reactants are slowly used up
rate of chemical reaction depends on…. what?
- collision frequency
- energy transferred during a collision
activation energy
the amount of energy needed for the reaction to occur
position of equilibrium depends on what conditions?
- temperature
- pressure
- concentration
what is Le Chatelier’s Principle used to predict?
the effect of any change you make to a reaction system
If you increase the pressure, the equilibrium tries to reduce it. It moved in the direction where there are ______ ____________ __ ___.
fewer molecules of gas
If you decrease the pressure, the equilibrium tries to increase it. It moves in the direction where there are _____ __________ __ ___.
more molecules of gas
If you change the concentration of either the reactants or the products, the system will __ ________ __ __ ___________.
no longer be at equilibrium
The rate of a chemical reaction tells us how _______ _ _______ _______ or how quickly a reactant is used up.
quickly a product is formed
The rate of a chemical reaction tells us how quickly a product is formed or how ______ _ ________ __ _____ __
quickly a reactant is used up
For chemical reactions to occur, reactant particles must ________ ___ ______ _______.
collide with enough energy
what are reactant particles that collide with enough energy called?
successful collisions
Name 4 factors that affect the rate of a chemical reaction
- concentration and pressure
- catalyst
- surface area
- temperature
large lumps of a solid have a ______ ______ __ ______ ______.
small surface area to volume ratio
In a closed system, reversible reactions can reach…
dynamic equilibrium
