3.1.2 Measuring changes in chemical reactions

Question 1

reactant

Answer 1

starting material that undergoes change during chemical reaction

Question 2

reagent

Answer 2

substance added to system to cause chemical reaction

Question 3

to figure out limiting reactant

Answer 3

1. n=m/M
2. divide by coefficient
3. the larger number is in excess
4. use mole of limiting reactant to figure out mole of product

Question 4

specific heat capacity

Answer 4

measure of amount of energy needed to increase tempo of specific quantity of substance by 1 degree
(reflects bonds in substance)

Question 5

heat loss minimisation

Answer 5

• lost from air around burning fuel and surface of water
• putting lid on container of water, insulating beaker, insulating around fuel

Question 6

calorimetry

Answer 6

experimental method of measuring heat energy released or absorbed by chemical reaction or physical process and minimising heat losses

Question 7

bomb vs solution calorimeter

Answer 7

• bomb: measures energy released by combustion reactions of gases
• solution: measures energy released by combustion reactions in solutions

Question 8

calibration factor

Answer 8

amount of energy required to change temp of water by 1 degree for that particular calorimeter

Question 9

electrical calibration

Answer 9

E=VIT
CF=E/delta T

Question 10

chemical calibration

Answer 10

E=n x delta H
CF=E/delta T

Question 11

energy transformation efficiency

Answer 11

• percentage of energy from a source converted to useful energy
• since due to first law of thermodynamics, total amount of energy is unchanged but not all energy is converted into one specific form

Question 12

why energy value is lower

Answer 12

• imperfect insulation leading to heat loss to surroundings
• heat produced during energy transformation
• incomplete combustion/reaction
• absorbed by a container