R1.1 Measuring enthalpy changes

Question 1

Chemical reactions involve a transfer of energy between?

Answer 1

the system and the surroundings

Question 2

What is the difference between heat and temperature?

Question 3

Which the direction of energy transfer between the system and the surroundings is taken in exothermic reactions?

Answer 3

system to surroundings

Question 4

if the temperature increases what type of reaction is it?

Answer 4

exothermic

Question 5

Which the direction of energy transfer between the system and the surroundings is taken in endothermic reactions?

Answer 5

system to surroundings

Question 6

How does the relative stability of reactants and products determines whether reactions are endothermic or exothermic?

Answer 6

if the products are more stable than the reactants the reaction is exothermic
if the products are less stable than the reactants the reaction is endothermic

Question 7

if the temperature decreases what type of reaction is it?

Answer 7

endothermic

Question 8

Describe the observations you would expect to make during an endothermic reaction?

Answer 8

the surroundings would cool down

Question 9

Describe the observations you would expect to make during an exothermic reaction?

Answer 9

the surroundings would heat up

Question 10

For energy profiles what should be the x axes be labelled as?

Answer 10

reaction coordinate

Question 11

For energy profiles what should be the y axes be labelled as?

Answer 11

potential energy

Question 12

how does the bonding in N2 explain the fact that its combustion is endothermic?

Question 13

Standard enthalpy change

Answer 13

is the heat transferred at constant pressure under standard conditions and states.

Question 14

Standred enthaply change can be determined by?

Answer 14

the change in temperature of a pure substance.

Question 15

the units of standred enthaply?

Answer 15

kJmol⁻¹

Question 16

How can the enthalpy change for combustion reactions, such as for alcohols or food, be investigated experimentally?

Answer 16

through calorimetry

Question 17

Why do calorimetry experiments typically measure a smaller change in temperature than is expected from theoretical values?

Answer 17

there would be a lot of excess heat loss so the enthalpy would always be lower than literature values

Question 18

Describe how to carry out calorimetry to determine enthalpy of combustion of alcohols and/or foods