rate equations and Kp

Question 1

what is the rate equation

Answer 1

rate= K[A]a[B]b

Question 2

what are the units of concentration

Answer 2

moldm-3

Question 3

what are the units of rate

Answer 3

moldm-3s-1

Question 4

what is a reaction order

Answer 4

the power to which a concentration is raised in the rate equation

Question 5

what does order of reaction tell us about a reaction

Answer 5

how changing the concentration will affect rate

Question 6

how do you determine the order of reaction

Answer 6

by doing an experiment and plotting the data on a graph

Question 7

what happens if you change the concentration of a reactant with order 0

Answer 7

no affect/ doesnt change

Question 8

what happens if you change the concentration of a reactant with order 1

Answer 8

the rate changes proportionally to the change in concentration

Question 9

what happens if you change the concentration of a reactant with order 2

Answer 9

the rate changes square proportionally to the change in concentration

Question 10

what happens to the rate constant if you increase the temperature

Answer 10

when the temp increases the rate constant increases as there is more kinetic energy in the particles and therefore more successful collisions

Question 11

what is initial rate and how can we work it out

Answer 11

the rate of the reaction at 0 and we can work it out by finding the gradient using a tangent or straight line

Question 12

why do we find the initial rate of a reaction

Answer 12

we can use initial rates to work out the rate equation by figuring out the orders of reactants

Question 13

how would we find out the rate equation experimentally

Answer 13

1. repeat experiment multiple times changing the concentration of A, B and C one at a time
   2, work out the initial rate for each experiment of each A, B and C
2. work out orders and then the rate equation

Question 14

What is the process of the Iodine Clock reaction

Answer 14

when we add hydrogen peroxide and iodine in solution together in the presence of starch the starch goes blue/black due to iodine and water being the products

1. add sodium thiosulfate and starch and time how long the colour change is
2. when you vary the concentration of iodine solution or hydrogen peroxide and keep all of the others constant you will be able to find out the order of the reactants by the changes in time taken and therefore initial rate according to the change in concentration

Question 15

what ways can you measure the rate of reaction

Answer 15

1. change in pH using a pH meter
2. Amount of gas lost using mole equations
3. volume of gas produced using gas syringe
4. colorimeter using calibration curve

Question 16

what is the rate determining step

Answer 16

the slowest step in a multistep reaction and appears in the rate equation

Question 17

how do we know all reactants in the rate equation affect rate

Answer 17

if they didn’t affect the rate then their order would be 0 and therefore wouldn’t appear

Question 18

other then reactants what else can appear in the rate equation

Answer 18

catalysts

Question 19

what is the arrhenuius equation

Answer 19

K = A x e to the power of -Ea/RT

Question 20

what does A stand for the in the Arrhenius equation

Answer 20

the arrhenuis constant

Question 21

what does R and T stand for the in arrhenius equation

Answer 21

R = gas constand
T = temperature in kelvin

Question 22

what does Ea stand for in the arrhenius equation

Answer 22

activation energy

Question 23

what is the simplified version of the Arrhenius equation that doesn’t involve e

Answer 23

ln(K) = ln(A) - (Ea/RT)

Question 24

how do you use an Arrhenius plot to work out activation energy

Answer 24

1. plot the graph of ln(K) over 1/t
2. draw a line of best fit
3. work out gradient which represents -Ea/R
4. gradient = -Ea/R then the gradient x R= -Ea

Question 25

what is the Arrhenius equation in the form of y=mx + c

Answer 25

ln(K) = (-Ea/R) x 1/T ln(A)
y = m x + c

Question 26

define the rate of reaction

Answer 26

change in conc per unit time measuring either products made of reactants used up

Question 27

equation for rate of reaction

Answer 27

change in concentration/time

Question 28

how do you measure the rate of reaction of really fast reactions

Answer 28

use a flash light to break bonds
use probs flashes to record amount of light absorbed by a species

Question 29

what is the overall order of reaction

Answer 29

all of the orders added together

Question 30

how could you tell that a second order graph really is second order reaction

Answer 30

draw concentration squared over rate graph and should be a straight line through origin