ASSESMENT EXAMS WITH CORRECT
QUESTIONS AND ANSWERS.
How do you measure the rate of a reaction? - CORRECT ANSWERS✔️✔️By measuring the quantity of a
reactant used or the quantity of product formed over time
What is the equation for calculating the mean rate of a reaction by measuring the amount of reactant
used? - CORRECT ANSWERS✔️✔️Mean rate of reaction = quantity of reactant used/time taken
What is the equation for calculating the mean rate of a reaction by measuring the amount of product
formed? - CORRECT ANSWERS✔️✔️Mean rate of reaction = quantity of product formed/time taken
What units can you measure the rate of a reaction in? - CORRECT ANSWERS✔️✔️g/s or cm3/s or mol/s
How do you calculate the rate of a reaction at a specific time from graph of the quantity of reactant used
or the quantity of product formed? - CORRECT ANSWERS✔️✔️By measuring the gradient of a tangent
drawn at that specific time on the graph
What are the five factors that can affect the rate of a reaction? - CORRECT
ANSWERS✔️✔️Concentration of reactants in solution, pressure of reacting gases, surface area of solid
reactants, temperature and the presence of a catalyst
What theory can we use to explain how various factors affect the rate of a reaction? - CORRECT
ANSWERS✔️✔️Collision theory
What is collision theory? - CORRECT ANSWERS✔️✔️Chemical reactions can occur only when reacting
particles collide with each other and with sufficient energy
,What is the activation energy of a reaction? - CORRECT ANSWERS✔️✔T️ he minimum amount of energy
that particles must have to react
According to collision theory why does increasing concentration of reactant in solution increase the rate
of the reaction? - CORRECT ANSWERS✔️✔️It increases the frequency of collisions and so increases the
rate of reaction
According to collision theory why does increasing the pressure of reacting gases increase the rate of the
reaction? - CORRECT ANSWERS✔️✔️It increases the frequency of collisions and so increases the rate of
reaction
According to collision theory why does increasing the surface area of solid reactants in solution increase
the rate of the reaction? - CORRECT ANSWERS✔️✔️It increases the frequency of collisions and so
increases the rate of reaction
According to collision theory why does increasing temperature increase the rate of the reaction? -
CORRECT ANSWERS✔️✔️It increases the frequency of collisions and makes the collision more energetic
and so increases the rate of reaction
How do you increase the surface area of a solid reactant? - CORRECT ANSWERS✔️✔️Grind it into a
powder that has smaller particle size
What effect does increasing the temperature of a reaction by 10°C have on the rate of a reaction? -
CORRECT ANSWERS✔️✔️It doubles it
What is a catalyst? - CORRECT ANSWERS✔️✔A
️ chemical that changes the rate of a chemical reaction
but is not used up in the reaction
How do catalysts increase the rate of a reaction? - CORRECT ANSWERS✔️✔️By providing a different
pathway for the reaction that has a lower activation energy
How do you know in a reaction that a chemical is used in a reaction is a catalyst? - CORRECT
ANSWERS✔️✔️It is not included in the chemical equation for the reaction
, What is a reversible reaction? - CORRECT ANSWERS✔️✔️Where the products of a chemical reaction
can react to produce the original reactants
What is the symbol used in reversible reaction equations that shows that the reaction is reversible? -
CORRECT ANSWERS✔️✔️
How can you change the direction of a reversible reaction? - CORRECT ANSWERS✔️✔️By changing the
conditions; for example heating or cooling the reaction
Describe the energy changes in a reversible reaction - CORRECT ANSWERS✔️✔️One direction will be
exothermic and the other direction endothermic
When is equilibrium in a reversible reaction achieved in apparatus which prevents the escape of
reactants and products? - CORRECT ANSWERS✔️✔️When the rate of the forward and reverse reactions
occur at exactly the same rate
What affects the relative amount of all the reactants and products at equilibrium in a reversible
reaction? - CORRECT ANSWERS✔️✔T️ he conditions
What happens to an equilibrium if any of the conditions change? - CORRECT ANSWERS✔️✔️The system
responds to counteract the change
What does Le Chatelier's principle predict? - CORRECT ANSWERS✔️✔️The effects of changing
conditions on a system at equilibrium
What affect will changing the concentration of one of the reactants in a reversible reaction have on the
equilibrium? - CORRECT ANSWERS✔️✔T️ he system will no longer be in equilibrium and the
concentration of all the substances will change until equilibrium is reached again
What happens when the concentration of a reactant is increased in a reversible reaction? - CORRECT
ANSWERS✔️✔️More products will be formed until equilibrium is reached again