Rate Of Reaction

Question 1

What is the average rate of a reaction

Answer 1

The total change in concentration of reactants/products divided by the time taken for the reaction to take place

Question 2

What is instantaneous rate

Answer 2

The rate of change occurring at a specific time in the reaction

Question 3

How to find instantaneous rate

Answer 3

Find gradient of tangent at point

Question 4

What must a property be to find the rate by dividing rate of change of property by time

Answer 4

Must be proportional to concentration as og equation was change in concen/time

Question 5

What is the rate of reaction

Answer 5

Measures the rate of formation of a product/ rate of removal of a reactant

Question 6

Two reasons why a reaction may get faster as it progresses

Answer 6

-if it is exothermic and the temperature rises
-if the reaction gives a product that can act as a catalyst for the reaction

Question 7

Experimental techniques to determine rate of reaction

Answer 7

-measure change in colour using colorimeter
-change in mass if gas produced (must be sufficiently dense or the change in mass is too small to measure on balance)
-volume of gas produced

Question 8

Methods to measure concentration changes

Answer 8

-quench reaction using sodium hydrogen carbonate and titrate with sodium thiosulfate and starch indicator
-measure electrical conductivity
-change in colour using colorimetry

Question 9

How to find initial rate of reaction

Answer 9

Draw tangent at t=0 and find the gradient of this tangent

Question 10

How to construct and use a calibration curve

Answer 10

Involves using a colorimeter to measure absorbance of solutions of known concen from which a calibration curve is plotted, then absorbance of sample from reaction mixture can be measured and calibration curve used to convert absorbance readings into concentration values