20 questions-rate and extent of chemical change

Question 1

whats the formula of mean rate of reaction in terms of reactants

Answer 1

quantity of reactant used up/ time taken

Question 2

whats the formula for mean rate of reaction in terms of products

Answer 2

quantity of products formed/time taken

Question 3

what are the 2 units for rates of reaction

Answer 3

g/s or cm2/s where s is seconds

Question 4

how can u calculate the rate of reaction at a certain time from a graph

Answer 4

draw a tangent to the curve and calculate the gradient

Question 5

whats collision theory

Answer 5

the theory that chemical reactions only occur when particles colide with sufficient energy

Question 6

which 5 factors effect the rate of reaction

Answer 6

temperature,surface area,concentration of a liquid,pressure of a gas,catalyst

Question 7

state the effect of increasing surface area on the rate of reaction

Answer 7

increases rate

Question 8

whats the name given to minimum amount of energy that reacting particles must have to react

Answer 8

activation energy

Question 9

explain why increasing the concentration increases the rate of reaction

Answer 9

there are more reactant particles therefor there are more frequent collisions between reactant particles which increases the chance of successful collisions

Question 10

whats a catalyst

Answer 10

substance that increases the rate of reaction without being used up or altered in the process

Question 11

how does a catalyst work

Answer 11

provides an alternative reaction pathway with a lower activation energy

Question 12

explain why decreasing temperature would decrease the rate of reaction

Answer 12

The reactant particles have less kinetic energy so their speed decreases. This results in less frequent collisions. Also fewer particles have the required activation energy therefore fewer collisions result in a reaction

Question 13

whats a reversable reaction

Answer 13

reaction that can go in both the forwards and backwards direction

Question 14

draw the symbol for a reversable reaction

Answer 14

arrow forward n arrow back

Question 15

when is a system in dynamic equilibrium

Answer 15

when the rate of forwards reaction is equal to the rate of backqards reaction

Question 16

does the amount of reactant change during equilibrium

Answer 16

no

Question 17

what is le chatliers principal

Answer 17

when conditions of a reaction at equilibrium are changed ot will short the position of equilibrium to countact the change

Question 18

a reaction is exothermic in the forward direction,what will occur if the temp is increased

Answer 18

equilibrium will shift to the left (backwards reaction) will increase as its endothermic which will bring the temperature back down

Question 19

what happens if a reaction is at equilibrium but some of the product was removed

Answer 19

equilibrium will shift to the right,the forward reaction will increase making more product to replace what was removed

Question 20

how does increasing the pressure effect equilibrium

Answer 20

it will shift the equilibrium to the side with fewer moles of gas