C6 20 Questions Flashcards
What is the formula for a mean rate of reaction in terms of reactants?
Quantity of reactant used up ÷ time taken
What is the formula for a mean rate of reaction in terms of products?
Quantity of product formed ÷ time taken
What are the two possible units for rate of reactions?
g/s or cm3/s (where s is seconds)
How could you calculate the rate of reaction at a particular time from a graph?
Draw a tangent to the curve and calculate the gradient
What is collision theory?
The theory that chemical reactions only occur when particles collide with sufficient energy.
Which five factors affect the rate of a reaction?
Temperature, surface area of a solid, concentration of solutions, pressure of gases, catalyst.
State the effect of increasing the surface area on the rate of a reaction.
Increases rate
What is the name given to the minimum amount of energy that reacting particles must have to react?
Activation energy
Explain why increasing the concentration increases the rate of reaction
There are more particles of reactant in solution, therefore there are more frequent collisions between reactant particles.
What is a catalyst?
A substance that increases the rate of a reaction without being used up or altered in the process
How does a catalyst work?
Explain why deceasing the temperature of a reaction would decrease the rate of a reaction.
When is a system in dynamic equilibrium?
When the rate of the forward reaction is equal to the rate of the backward reaction.
What is a reversible reaction?
A reaction that can go both in the forwards and backwards.
What is the symbol for a reversible reaction?
Is the amount of reactant changing at equilibrium?
No
What is Le Chatelier’s principle?
When the conditions of a reaction at equilibrium are changed, it will shift the position of equilibrium to counteract that change.
A reaction is exothermic in the forward direction. What will occur if the temperature is increased?
Equilibrium will shift to the left, the backwards reaction will increase as it is endothermic and this will decrease the temp
A reaction is at equilibrium when some of the product is removed. What will occur?
Equilibrium will shift to the right, the forward reaction will increase making more product to replace what was removed.
How does increasing the pressure affect equilibrium?
It will shift equilibrium to the side with fewer moles of gas
