Chemistry 4.3 Flashcards
Explain what happens to rate of reaction when you increase surface area of solid?
Rate increases
More of the solid is accessible
More collisions per unit time
More successful collisions per unit time
Explain what happens to rate of reaction when you increase the concentration of the solution
Rate increases
More particles per unit volume
More collisions per unit time
More successful collisions per unit time.
Explain what happens to the rate of reaction when you increase the temperature
Rate increases
Particles gain more kinetic energy
More successful collisions per unit time
Higher proportion of collisions are successful
(more particles have energy greater than the activation energy)
Explain what happens to the rate of reaction if a catalyst is added
Rate of reaction increases
Catalyst provides an alternative reaction pathway with a lower activation energy.
More particles have the required activation energy
Higher proportion of collisions are successful
More successful collisions per unit time
Definition of catalyst
A chemical that speeds up a reaction without being used up
Test for oxygen
Relights a glowing splint
Example of a catalyst
Manganese (IV) oxide
Observations when a metal carbonate is added to acid
Effervescence
Solid disappears
Explain how increasing air pressure affects rate of reaction
Rate of reaction increases
More particles per unit volume
More collisions per unit time
More successful collisions per unit time
Test for carbon dioxide
Bubble through limewater
Turns cloudy
Why can’t sulphuric acid be used for the reaction with marble chips?
Marble chips and sulfuric acid would react to make calcium sulphate which is insoluble and would form a layer on the marble chips, slowing down the reaction
Why does rate decrease as time goes on during the reaction of marble chips and hydrochloric acid when marble chips are in excess?
Acid concentration is highest at the start so rate is highest, lots of frequent collisions
Rate decreases as acid becomes more dilute and more particles are used up so less frequent collisions
Rate stops/levels off when all the acid has been used up
During the reaction of marble chips and hydrochloric acid, why is cotton wool placed in the neck of the conical flask?
To prevent loss of acid (spray)
or to ensure that only the gas could escape
Chemical and word equation for marble chips
CaCO3
Calcium carbonate
Apparatus used to measure volume of gas produced
Gas syringe
Which collision theories causes proportion of successful collisions to increase?
Increasing temperature and adding a catalyst
What is produced that causes the cross to disappear in the reaction between sodium thiosulphate and hydrochloric acid?
Sulfur
What is the relationship between concentration and rate
Rate is directly proportional to concentration
What does a graph showing direct proportion look like?
A straight line through the origin.
What does collision theory state is needed for a reaction to occur?
Particles must collide
Particles must have at least the activation energy
The more frequent the collisions the….
faster the reaction rate
