rate reactions Flashcards
What dose the slope of the line gives us an idea of
Of the rate of reaction
The steeper the slope
The faster the reaction
What dose the less steep of the line show
The reaction is decreasing
Why dose the reaction eventually slow down
Because a lot of the reaction molecules have already reacted and turned into product
What dose the slope of the line tells us
The reaction has stopped
How do u calculate the mean rate of reaction
60 divided by 15 = 4g/s
How do sentient get the rate of reaction at any point of the graph
They do it buy drawing a straight line at any point we. All this the tangent
What dose the slope of tangent gives us an idea of
The rate of reaction
What can this tangent tell us
That the reaction is faster at the start and slower towards the end
What is collision theory
Can only take place when the reacting partials collide with each other and they must have energy
The rate of collisions is determined by the frequency of successful collisions
Frequency = number of successful collisions per second
What happened to the rate of Collins on this graph
At the start it have a high frequency of collision per second but as it moves towards the end the frequency of collision per second decreases
What is a hypothesis
Is a proposal that could explain a fact of observation
It must be testable
What do we get if we react sodium thiosulfate solution + hydrochloride acid what do we get
Sulfur (solid) and makes the solution go cloudy
What do scientists call it when a solution goes cloudy
Turbidity
What can we use to know when a reaction is finished
With the reaction sodium thiosulfate solution + hydrochloride acid =
Sulfur when the Sulfur goes cloudy
Practical 5 chemistry
First we use a measuring cylinder to put 10cm3 of sodium thiosulfate solution into the flask then we put the flask on a black cross then we add 10cm3 of hydrochloride acid into the flask now swirl the solution and start the stopwatch then we look down at the flask after some time the solution will turn cloudy we stop the clock when we can’t see the cross repeat using lower concentrations and carry out the experiment then calculate mean values
What are the reproducibility to the partial 5 chemistry
People have different eyesights some people ca see the cross for longer disadvantage
Advantage
Used the same side cross not be problem
What is the practical for this experiment
First we use a measuring cylinder to place 50cm3 of hydrochloride acid into a flask then we connect the flask to a bung and a delivery tube then we place the end of the deliver tube to a container of water then we place a upside down measuring cylinder also filled with water into the delivery tube then we add a 3cm strip of magnesium to the hydrochloric acid abs start the stop watch
What does this practical overall do
The reaction produces hydrogen gas which is trapped in the measuring cylinder every 10 seconds measure the volume of hydrogen of gas in the measuring cylinder and continue to no more hydrogen given off
Surface area to volume
Smaller sized blocks of solid reactant have a greater surface area to ratio the larger blocks more collions per second
Surface area practical
We place are reaction on a balance as carbon dioxide is produced the mass decreases we can use this to calculate the rate of reaction the cotton wool allows carbon dioxide gas to escape it also prevents acid to splashing out of the flask if acid did splash out it cause the mass to fall causing an anomalous result
We’re the activation energy
What is the activation energy
Is the minimum amount of energy that the partials must have in order to react (to collide successfully )
What dose increasing the temperature also increase
The rate of reactions because increasing the temperature increases the rate of partials move faster more energy
What are catalysts
Catalysts increase the rate of chemical reaction but are not used up during the reaction
What do catalysts use to carry out the reaction
Quickly saving up energy
How do catalysis increase the rate
By providing a different pathway for the reaction that has a lower activation energy
Do we include catalysis in the chemical equation for a reaction
No we don’t include them because they are not used up in the reaction
Different reactions need different
Catalysis
What do enzymes act as in living organisms
Catalysis
What way does this reaction go
Forwards in one direction magnesium oxide will not turn back into magnesium and oxygen
Reverse able reaction
You have heat to form the reaction and cold to reverse it
What colour is hydrated copper sulfate
Blue
What colour is hydrated copper sulfate if we heat it
It reacts to form anhydrous copper sulfate which is white
Exothermic reaction
gives out heat
Endothermic reaction
takes in heat
If the forwards reaction is endothermic what is the reversible reaction
exothermic
What is equilibrium
When the foreword and the reversible reaction will take place in the exactly the same rate
