Rates Of Reaction and Energetics paper 2

Question 1

What does increasing the concentration do to the rate of reaction

Answer 1

• increasing the concentration increases the number of particles in a given volume
• this means more frequent successful collisions
• therefore the rate increase

Question 2

What are catalysts

Answer 2

A substance that increase the rate of a reaction, but is chemically unchanged at the end of the reaction

Question 3

What does surface area do to the rate of reaction?

Answer 3

• increasing surface area increases surfaces for collisions
• this means more frequency successful collisions
• therefore the rate increases

Question 4

Marble chip experiment

Answer 4

CaCO3 + 2HCl —> CO2 + CaCl3 + H2O

Marble chips + hydrochloric acid —> carbon dioxide + calcium chloride + water

Effect of change in surface area or concentration on rate of reaction

Question 5

What does increasing the temperature do to the rate of reaction

Answer 5

• increasing the temperature means that the particles have more energy so they move faster
• more particles have the required activation energy
• more frequent successful collisions
• the rate increases

Question 6

What do catalysts do

Answer 6

They increase the rate of reaction by providing an alternative pathway with lower activation energy

Question 7

Exothermic

Answer 7

chemical reactions in which heat energy is given out

Question 8

Endothermic

Answer 8

chemical reactions in which heat energy is taken in

Question 9

Displacement, dissolving and neutralisation reactions

Answer 9

50 cm3 of copper(II) sulfate is measured and transferred into a polystyrene cup.
The initial temperature of the copper sulfate solution is measured and recorded.
Magnesium is added and the maximum temperature is measured and recorded.
The temperature rise is then calculated

Question 10

Combustion reactions

Answer 10

The initial mass of the ethanol and spirit burner is measured and recorded.
100cm3 of water is transferred into a copper container and the initial temperature is measured and recorded.
The burner is placed under of copper container and then lit.
The water is stirred constantly with the thermometer until the temperature rises by, say, 30 oC
The flame is extinguished and the maximum temperature of the water is measured and recorded.
The burner and the remaining ethanol is reweighed.

Question 11

Equation for heat energy change from a measured temperature change

Answer 11

Q = mcΔT

Question 12

Molar enthalpy change (kj/mol) =

Answer 12

amount of heat energy transferred (Q) / number of moles

Question 13

Activation energy

Answer 13

the minimum amount of energy required to start the reaction