C6 Rates Of Reactions Flashcards
Rate of reaction equation
Amount of reactant used or amount of product formed / time
RP5: effect of concentration on rates of reaction (part a (cross))
1) add 2cm 3 of sodium thiosulfate to a mini tube in a tub over a cross
2) add 8 cm 3 water
3) add 2cm 3 of hydrochloric acid into the tube, stir and start timer
4) stop the clock when you no longer see cross
6) repeat, but change the concentration of thiosulfate and water each time.
HYPOTHESIS: a precipitate will be formed quicker if the concentration of the reactants is greater
Variables of RP5 part a (cross)
Dependant : time taken for cross to disappear
Indépendant : concentration of sodium thiosulftae
Control : amount of hydrochloric acid added
RP5 : effects of concentration on rates of reaction part b (gas cylinder)
1) set up an upside down measuring cylinder filled with water in a bowl of water attached to a delivery tube and bung
2) add 50cm 3 hydrochloric acid to a flask
3) add 3cm 3 of magnesium ribbon
4) quickly attach bung to flask and start timer
5) record the volume of gas every ten seconds until gas stops being produces
6) repeat with different concentrations of hydrochloric acid
Variables of RP5 part b (gas in cylinder)
Dependant : volume of gas produced
Independent: hydrochloric acid concentration
Control: magnesium a amount
What is collision theory?
Particles must collide with sufficient energy and frequency and orientation for a reaction to occur
What is activation energy?
The minimum amount of energy needed for a reaction to occur
How does increasing concentration affect rate?
Increases rate (more collisions frequency), proportional
How does increasing pressure affect rate?
Increases rate (more frequent collisions)
How does increasing temperature affect rate?
Increases rate (more energy I collisions and more frequent collisions)
What are catalysts?
Speed up a reaction by reducing the activation energy and creating a new pathway for particles without being used up
What is a reversible reaction?
A reaction where the products can form the reactants again
What is a hydrated salt?
Contains water in its structure
What is an anhydrous salt?
Does not contain water molecules
What is the equilibrium?
When the rate of the forwards reaction is equal to the rate of the backwards reaction within a closed system
What is le chateliers principle
When the conditions of a system at equilibrium changes, the system change es to counteract the change
What way does the equilibrium shift to favour the forwards reactions?
Right
How is the equilibrium affected if you increase the temperature?
It favours the endothermic reaction (takes in excess heat and cools surroundings)
How is the equilibrium affected if you decrease the temperature?
The Exothermic reaction is favoured (releases energy to warm surroundings)
How does increasing the pressure affect the equilibrium?
The equilibrium favours the side of the reaction which produces fewer gas molecules
How is the equilibrium affected if the pressure decreases?
The reaction which produces more gas moelecules
How is the equilibrium affected if the concentration of a reactant increases?
Equilibrium favours the forwards reaction and shifts to the right
How will equilibrium be affected if the concentration of a reactant decreases?
Shifts left to favour the backwards reaction (decreases yield)
