C8 rates and equilibrium Flashcards
What is the mean rate of reaction(rate)?
quantity of reactant used/time taken OR
quantity of product formed/time taken
What is usually the unit for rate
g/s
How to measure the change in volume?
The change in
volume
of a reactant or product can be followed during a reaction. This method is useful when a gas leaves the reaction container. The volume of a gas is measured using a gas syringe, or an upside down
burette
or measuring cylinder.
What does the gradient of a graph represent in a mass or volume against time graph?
rate
the steeper the line, the greater the ______
rate
How to calculate the rate AT a specific time
draw a tangent to the curve
What is the activation energy?
The minimum amount of energy required to break or make bonds and start reactions between particles
Reactions are more likely to happen when you:
-increase the frequency of reacting particles colliding with each other
-increase the energy they have when they collide
What happens to the rate of reaction when the surface area:volume ratio is increased in the reactants?
Frequency of collisions increases so rate of reactions increases.
How does increasing temperature affect rate?
frequency of collisions increases,
more particles collide with energy greater than the activation
energy in any given time increases the rate
What happens when concentration OR pressure of reacting gas is increased?
If the
concentration
of a reacting
solution
or the
pressure
of a reacting gas is increased:
the
reactant
particles
become more crowded
the frequency of collisions between reactant particles increases
the rate of reaction increases
How does a catalyst work in increasing rate?
A catalyst provides an alternative
reaction pathway that has a lower activation energy than the uncatalysed reaction. This does not change the frequency of collisions. However, it does increase the frequency of successful collisions because more particles have energy greater than the activation energy, therefore there are more successful collisions. They also do not alter the products of a reaction.
Why are catalysts used in industry?
It increases rate of reaction therefore reducing energy costs.
What is the sign of a reversible reaction?
⇌
What is the forward and backward reactions in the sign?
the forward reaction is the one that goes to the right
the backward reaction is the one that goes to the left
What is a reversible reaction?
the
products
of the reaction can react together to produce the original
reactants
Example of reversible reaction:
Blue copper sulfate is described as
hydrated
. The copper
ions
in its
crystal lattice
structure are surrounded by water
molecules
. This water is driven off when blue hydrated copper sulfate is heated, leaving white
anhydrous
copper sulfate. This reaction is reversible:
hydrated copper sulfate ⇌ anhydrous copper sulfate + water
CuSO4.5H2O(s) ⇌ CuSO4(s) + 5H2O(l)
The forward reaction is endothermic and the reverse reaction is exothermic.
What is meant by equilibrium?
In chemical reactions, a situation where the forward and backward reactions happen at the same rate, and the concentrations of the substances stay the same in a closed system.
One reaction is endothermic and the other is exothermic in which types of reaction?
Reversible reaction
Why is equilibrium described as dynamic and not static?
Although concentrations of reactants and products unchanged
overall in reaction mixture,
forward and reverse reactions still taking place but at the same
rate.
What is le chateliers principle?
When a change is made to a system at equilibrium, the position of equilibrium moves to counteract the change that was made. For example, if the temperature is increased, the position of equilibrium moves in the endothermic direction to reduce the temperature.
What happens if pressure is increased in equilibrium?
If the pressure is increased in a reaction involving gases, the equilibrium position moves in the direction of the fewest
molecules
of gas, to reduce the pressure.
