CHAPTER 8 Flashcards
what is the rate of reaction
how fast reactants turn into products
using a graph, how do you find the rate of reaction at a specific time
draw a tangent to the curve (a straight line)
turns this into a right angled triangle with the tangent as the hypotenuse
calculate the gradient and add the units
how can you find the rate of reaction without a graph
how quickly the reactants are used up or how quickly products are made
the steeper the gradient of a tangent
the quicker the reaction
how to calculate the mean rate of reaction
quantity of reactant used / time
quantity of product formed / time
what are the four factors that effect the rate of reaction
concentration, pressure, surface area, temperature, and use of a catalyst
what is collision theory
the idea that particles don’t just have to bump each other, they have to do so hard enough to react
what is activation energy
the minimum amount of energy particles need before they react
why does a smaller surface area speed up a reaction
more area is exposed to the liquid and are able to react
a smaller surface area = larger
surface area to volume ratio
what are the two reasons why temperature increases rate of reaction
particles collide more often they collide with more energy
why does heating a substance mean the particles collide more often
the particles absorb the heat energy and convert it to kinetic
why does something fizz when it reacts
release of carbon dioxide
how to test for carbon dioxide
turns limewater
at room temperature if you increase it by 10 degrees what happened to the rate of reaction
it doubles
why are reactions more common with a higher temperature
more particles have a temperature higher than the activation energy
why does increasing the concentration increase the rate of reaction
there are more of the particles so collisions are more likely
how to test for hydrogen
squeaky pop on a glowing splint
how does increasing the pressure increase the rate of reaction
the same number of particles in a smaller space so reactions are more common
what is a catalyst
speeds up a reaction without being effected itself
how do catalysts work
the provide another route to the products with a lower activation energy so reactants take this route and the reaction is faster
advantages of catalysts
cost effective - would be more expensive to pay for extra energy helps environment can be reused
what is a reversible reaction
when the reactants react to make the products and the products break down to form reactants
what is the symbol for a reversible reaction
two half arrows
in a reversible reaction what is endothermic
going from products to reactants
in a reversible reaction what is exothermic
reactants to products
what is a closed system
when nothing can escape
what is equilibrium
when the forward reaction = reverse reaction
what is the forward reaction
reactants to products
what is the reverse reaction
products to reactants
why is equilibrium described as dynamic
because although you cant see it, reactions are still taking place on an atomic level
what was la chateliers principle
that when you alter the conditions of an equilibrium, the equilibrium shifts to cancel out the change
if you increase one of the reactants in an equilibrium then…
the equilibrium shifts left so the reverse reaction happens faster than the forward and more reactant is made
under what pressure conditions will an equilibrium change
when there are different moles of particles on each side
if there are the same number of moles on each side of the equilibrium and you increase the pressure, what does it do
nothing
if you increase the temperature of one side of the equilibrium what will it do
shift to make more of the endothermic side which results in a drop in temperature
decreasing the temperature makes the equilibrium favour the
exothermic reaction
how to tell from a graph when a reaction has finished
the line goes flat
when is the reaction going fastest from a graph
when the line is steepest
what happened when the product of a reaction is a precipitate
the solution goes cloudy
how to measure the rate of reaction when the product is a precipitate
draw a cross on paper under the conical flask record the time for it to disappear
how to measure rate of reaction using mass of gas given off
the faster the number on the balance drops, the faster rate of reaction measure at frequent intervals
how to measure the rate of reaction using volume of gas
use a gas syringe to capture any gas produced more gas produced, faster rate of reaction
how to measure the rate of reaction of magnesium and HCl
set up the experiment attach a gas syringe to the top of the conical flask. record the volume of gas produced at regular intervals plot the data and analyse
how to measure rate of reaction of sodium thiosulfate and HCl
set up the experiment over a black cross time the time taken for the cross to disappear under the cloudy sulphur
how to work out the limiting reactant of the equation
work out the number of moles of each of the reactant look at the equation to see how many moles of one react with the other calculate which will be used up first -the limiting reactant
where will dynamic equilibrium only take place
close system
what is a dynamic equilibrium
when both reactions are happening but at the same rate, so there is no overall effect
what can anhydrous copper sulfate be used to test for
water
what are the three changes the equilibrium will try to counteract
temperature concentration pressure
what will the equilibrium do if you increase the concentration of the products
shift left to make more reactants
