2.1 Enthalpy

Question 1

Work=?

Answer 1

Force × distance

Question 2

Define 1 Joule

Answer 2

The amount of energy required to raise a 1kg substance, 10cm against the force of gravity

Question 3

Define 1 calorie

Answer 3

The amount of heat necessary to raise the temperature of exactly 1g of water by 1°C

Question 4

One food calorie =

Answer 4

1000cal OR 1kcal

Question 5

5 types of Energy (KC PEN)

Answer 5

Kinetic
Chemical
Potential
Electromagnetic
Nuclear

Question 6

Potential Energy (E) =

Answer 6

mgh

Question 7

Kinetic Energy (E) =

Answer 7

½mv²

Question 8

What is the first law of thermodynamics?

Answer 8

The energy of the universe is constant

Question 9

Equation for change in Internal Energy (E)

Answer 9

ΔE = q + w

q = heat
w = work

Question 10

What does Enthalpy Change (ΔH°) show?

Answer 10

It shows whether heat is released or absorbed during a chemical process

Question 11

Enthalpy Change (ΔH°) formula

Answer 11

Products Enthalpy- Reactants Enthalpy

Question 12

Heat/work put into a system, in a calculation, is a ……….. value

Answer 12

Positive

Heat/work put into system is endothermic

Question 13

Is “work on the surroundings” positive change or negative?

Answer 13

Negative

Question 14

What are the standard conditions of an element in its standard state?

Answer 14

Pressure = 1atm
Temperature = 25°C or 298K
Concentration for solutions = 1M

Question 15

In exothermic reactions, the products are……..?

Answer 15

More stable

Question 16

In endothermic reactions, the products are…..?

Answer 16

Less stable

Question 17

Respiration
Endo or Exo?

Answer 17

Exothermic

Question 18

Electron exited up a n group
Endo or Exo

Answer 18

Endothermic (energy put in)

Question 19

Standard enthalpy of formation is….

Answer 19

The change in enthalpy when one mole of a compound is formed from its elements in their standard states

Question 20

Pure element enthalpy of formation?

Answer 20

Defined as zero in its standard state

Question 21

What is used to measure energy changes?

Answer 21

Colorimeter (works well with exothermic reactions)

Question 22

Enthalpy Change equation?

Answer 22

ΔH = MCΔT

Question 23

What is Hess’ law?

Answer 23

Overall enthalpy change in a reaction is independent to the route taken from reactants to products

Question 24

Breaking bonds is?

Answer 24

Endothermic (energy put it)

Question 25

Enthalpy Change formula

Answer 25

Bonds broken - bonds formed

Question 26

Making bonds is?

Answer 26

Exothermic (negative value)

Question 27

What equation is used to find enthalpy of a reaction when given all enthalpies of formation?

Answer 27

ΔH(reaction) = ΣHf (products) - ΣHf (reactants)

Question 28

Remember ion formation Equations/definitions for born harber cycles

Answer 28

First ionisation energy
Enthalpy of atomisation
Lattice enthalpy

Etc

Question 29

Semester 1 knowledge required on Tom Robshaw workshop

Answer 29

Delivered 25/04

Question 30

Heat/work taken out of a system, in a calculation, has a ……….. value

Answer 30

Negative

Heat/work taken out of a system is exothermic