SAC 2 Flashcards
1
Q
exothermic reaction
A
- describes a chemical reaction in which energy is released to the surroundings.
- negative △H value
- released
- high to low
- external temp increases
2
Q
endothermic reaction
A
- describes a chemical reaction in which energy is absorbed from the surroundings.
- positive △H value
- absorbed
- low to high
- external temp decreases
3
Q
collision theory/orientation
A
- matter can not be created or destroyed in a chemical reaction
- some orientations during collision process increases the chance of old bonds being broken enhancing successful collision
- correct orientation increases the chance of successful collision and a reaction taking place
4
Q
how a reaction occurs
A
MUST:
- collide
- have the correct orientation
- have sufficient energy
5
Q
activation energy
A
- for a reaction to occur, reactants must have energy equal to or greater than the level of activation energy
- is always a requirement before a reaction can occur
- UNDERSTAND GRAPH
6
Q
affecting rate of reaction: concentration
A
- amount of substance in a given volume
- increasing the concentration rate of a reactant increase rate of reaction
- concentration is increased through the crowding together of particles
(this increased concentration increases the number of overall collisions in a period of time therefore increasing the amount of successful collisions therefore resulting in a higher rate of reaction)
(this is the same with gas pressure)
7
Q
affecting rate of reaction: temperature
A
- as temp increases particles move faster and have greater kinetic energy, due to this increases energy more successful collisions should occur and the rate of reaction will be greater
8
Q
affecting rate of reaction: surface area
A
- as more substances are brought into contact with other substances more particles are exposed which produces more collisions and therefore more successful collisions and therefore increases rate of reaction
- can result in catastrophic & unexpected results
9
Q
open system
A
- both energy and matter can be transferred to and from it’s surroundings
- reactants and products are not contained
- particles evaporate and mass is lost
10
Q
closed system
A
- energy but NOT matter can be transferred to and from it’s surroundings
- all reactants and products are contained
- particles evaporate, mass is not lost, increase in gas pressure
11
Q
catalysts
A
- alter the rate of chemical reaction without being consumed
- increases the rate of reaction without a change in it’s own concentration
- speeds up reactions, does not alter the △H value, provides alternative pathways
12
Q
rate of a reaction
A
- is an indication of how fast a reaction proceeds
- speed at which a chemical reaction proceeds
13
Q
extent of a reaction
A
- the degree to which reactants are converted into products
- extent to which the reaction has proceeded
- describes the equilibrium position
