enthalpy

Question 1

what is the enthalpy change of a reaction?

Answer 1

the heat energy it releases or absorbs per mole

Question 2

+ means what for the heat energy?

Answer 2

absorbed

Question 3

• means what for the heat energy?

Answer 3

released

Question 4

+ heat energy is known as what?

Answer 4

endothermic

Question 5

• heat energy is known as what?

Answer 5

exothermic

Question 6

does breaking bonds release or absorb energy?

Answer 6

absorbs energy

Question 7

does making bonds release or absorb energy?

Answer 7

releases energy

Question 8

what is calorimetry?

Answer 8

an experimental method used to measure an enthalpy change

Question 9

calorimetry : what happens in an exothermic reaction?

Answer 9

• the reaction releases heat energy
• that heat energy is absorbed by nearby water
• the temperature of the water increases

Question 10

what does the simplest form of calorimetry involve?

Answer 10

• combusting a fuel to heat up the water

Question 11

method for combustion calorimetry? (4 steps)

Answer 11

1) weigh out 50g of water and place it in a can above the burner
2) measure the initial mass of the burner and the initial temperature of the water
3) ignite the burner, stir water for 30 seconds, then extinguish the burner
4) measure the final mass of the burner and the final temperature of the water

Question 12

what are the 2 most significant causes of error in combustion calorimetry?

Answer 12

• heat loss - most of the heat energy dissipates into the air instead of the water
• incomplete combustion - this releases less heat energy than expected

Question 13

what is the method used for solution calorimetry? ( 4 steps)

Answer 13

1) pipette 25cm3 of CuSO4 into a polystyrene cup
2) measure the initial temperature of the solution
3) add 1g of Mg and stir continuously
4) measure the maximum temperature of the solution

Question 14

what are 3 significant causes of error in solution calorimetry?

Answer 14

• heat loss
• incomplete reaction
• the water wasnt pure water- it has things dissolved in it, that means the SHC of the water is not 4.18 anymore