Developing Fuels

Question 1

What is the ideal gas equation?

Answer 1

pV=nRT

Pressure x volume = moles x 8.314 x temp K

Pa x m^3 = moles x J/K/mol x K

Question 2

What volume of gas does 1 mole of a substance take up?

Answer 2

24dm^3 at room temp and pressure

Question 3

How do you convert cm^3 to dm^3

Answer 3

divide by 1000

Question 4

How do you convert dm^3 to m^3

Answer 4

divide by 1000

Question 5

In the ideal gas equation what is volume measured in?

Answer 5

m^3

Question 6

In the ideal gas equation what is temperature measured in?

Answer 6

Kelvin

Question 7

How do you convert Celsius to Kelvin

Answer 7

Add 273

Question 8

What can you use to measure gas produced by a reaction?

Answer 8

A gas syringe

Question 9

In chemistry what is room temperature and pressure?

Answer 9

298 K (25 Celcius) 100KPa

Question 10

Whats the equation for volume of gas at RTP

Answer 10

Moles = (volume in dm^3) / 24

Question 11

What causes a change in enthalpy in a reaction?

Answer 11

bonds being made and broken

Question 12

What are the standard conditions

Answer 12

298K and 100KPa

Question 13

What are the four main stages of heterogeneous catalysis

Answer 13

Stage 1: adsorption to catalyst
Stage 2: reactants bonds break
Stage 3: New bonds made
Stage 4: Loss of product from catalyst surface

Question 14

When calculating enthalpy changes do you pay attention to moles in the reaction

Answer 14

Yes - times by average bond enthalpy

Question 15

What is standard enthalpy change of reaction?

Answer 15

Enthalpy change when reaction occurs in the molar quantities shown in chemical reaction
under standard conditions

Question 16

What is the standard enthalpy change of formation?

Answer 16

enthalpy change when 1 mole of a compound is formed from its elements in standard states under standard conditions

Question 17

What is standard enthalpy change of combustion

Answer 17

enthalpy change when 1 mole of a substance is completely burnt in oxygen under standard conditions

Question 18

How do you calculate enthalpy change of reaction

Answer 18

(Energy absorbed to break bonds) - (Total energy released in making bonds)

Using average bond enthalpies

Question 19

What states must compounds be in when bond enthalpies are measured?

Answer 19

gas

Question 20

What do you do to work out number of molecules?

Answer 20

work out moles and times by avogadro’s constant

Question 21

What is an exothermic reaction?

Answer 21

A reaction which gives out energy

Question 22

What does a shorter bond length mean?

Answer 22

Means a stronger attraction and higher bond enthalpy

Question 23

What is average bond enthalpy?

Answer 23

the energy need to break one mole of bonds in the gas phase

averaged over many different compounds (explains why it’s not exact)

Question 24

What is bond length?

Answer 24

Distance between two positive nuclei repelling and the attraction of electrons balanced

Question 25

What are bond enthalpies measured in?

Answer 25

KJ/mol

Question 26

Is bond breaking exothermic or endothermic?

Answer 26

endothermic

Question 27

Is bond making exothermic or endothermic

Answer 27

exothermic

Question 28

What is an endothermic reaction?

Answer 28

absorbs energy - temp decreases

Question 29

What is Hess's law?

Answer 29

The total enthalpy change of a reaction is always the same no matter what route is taken

Question 30

Do moles matter when calculating enthalpy changes using Hess's cycles and standard enthalpies?

Answer 30

Yes (times amount of moles of product by enthalpy change for it)

Question 31

What does an enthalpy level diagram look like for an endothermic reaction?

Answer 31

products higher than reactants

Question 32

what does an enthalpy level diagram look like for an exothermic reaction?

Answer 32

reactants higher than products

Question 33

What's different about an enthalpy level diagram with a catalyst?

Answer 33

It has two bumps

Question 34

What is activation energy?

Answer 34

minimum amount of energy needed to begin breaking bonds and start a chemical reaction

Question 35

What does less enthalpy mean for a substance?

Answer 35

more stable

Question 36

What is the equation for enthalpy changes?

Answer 36

``` q = mcΔT q= heat change m= mass of water or solution ```

Question 37

What is standard enthalpy change of neutralisation?

Answer 37

Enthalpy change when an acid and alkali react to form 1 mole of water

Question 38

Why is the enthalpy of combustion in a lab likely to be a lower value then in a data book?

Answer 38

not done in standard conditions

Question 39

In q=mcΔT does it matter if T is kelvin or celsius?

Answer 39

no

Question 40

What is a catalyst?

Answer 40

Increases the rate of reaction by providing an alternative reaction pathway with a lower activation energy The catalyst is chemically unchanged at the end of the reaction

Question 41

What catalyst is used in the haber process?

Answer 41

iron Fe N2 + 3H2 --> 2NH3

Question 42

What is used to test for alkene products?

Answer 42

bromine water

Question 43

why are catalysts used in cracking?

Answer 43

without one it requires high temp and pressure making it expensive

Question 44

How are catalysts used in cracking

Answer 44

Hydrocarbon vapour over heated solid catalyst