developing fuels (DF) Flashcards

1
Q

What is the ideal gas equation?

A

pV = nRT

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2
Q

What is enthalpy change?

A

Heat energy transferred in a reaction at constant pressure.

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3
Q

What is an exothermic reaction?

A

A reaction that gives out energy, resulting in a temperature increase.

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4
Q

What is an endothermic reaction?

A

A reaction that absorbs energy, resulting in a temperature decrease.

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5
Q

How do you calculate enthalpy change from bond enthalpies?

A

Energy absorbed when bonds are broken - energy released when bonds are made.

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6
Q

What are average bond enthalpies?

A

Energy needed to break one mole of bonds in the gas phase, averaged over many compounds.

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7
Q

What is bond enthalpy related to?

A

The distance between two nuclei where repulsive and attractive forces balance.

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8
Q

How does bond enthalpy relate to attraction and bond length?

A

Stronger attraction = higher bond enthalpy and shorter bond length.

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9
Q

What is Hess’s Law?

A

The total enthalpy change is always the same regardless of the route taken.

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10
Q

What do enthalpy level diagrams show about stability?

A

Substances with lower enthalpy are more stable.

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11
Q

Why are intermediates usually short-lived?

A

They have very high enthalpy and quickly convert into products.

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12
Q

What is the standard enthalpy change of neutralisation?

A

The enthalpy change when an acid and alkali react under standard conditions to form one mole of water.

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13
Q

What is the formula for calculating enthalpy change?

A

q = m × c × ΔT

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14
Q

What do the variables in q = mcΔT represent?

A

q = heat energy (J), m = mass of solution (g), c = 4.18 J/g/K, ΔT = temperature change (K).

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15
Q

What is a catalyst?

A

A substance that increases the rate of reaction by lowering the activation energy and remains chemically unchanged.

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16
Q

What is a heterogeneous catalyst?

A

A catalyst in a different state to the reactants.

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17
Q

How do heterogeneous catalysts work?

A

Via adsorption (bond breaking), radical formation, bond formation, and desorption.

18
Q

What is catalyst poisoning?

A

When impurities like CO or lead bind to the surface of a catalyst, preventing it from functioning.

19
Q

What is an aromatic compound?

A

A compound that contains a benzene ring.

20
Q

What is an aliphatic compound?

A

A compound that does not contain a benzene ring.

21
Q

What is a sigma bond?

A

A bond formed by head-on overlap of orbitals with maximum electron density along the axis.

22
Q

What is a pi bond?

A

A bond formed by sideways overlap of p orbitals; found in double bonds and weaker than sigma bonds.

23
Q

Why can’t atoms rotate around double bonds?

A

Because pi bonds restrict rotation.

24
Q

What are structural isomers?

A

Compounds with the same molecular formula but different structures.

25
Q

What is E/Z isomerism?

A

A type of stereoisomerism caused by restricted rotation around double bonds.

26
Q

What is the difference between cis and trans isomers?

A

Cis = Z (same side), Trans = E (opposite sides).

27
Q

What is used to convert alkenes to alkanes?

A

A platinum catalyst.

28
Q

How do you test for carbon-carbon double bonds?

A

Add bromine water and shake; orange to colourless indicates a double bond.

29
Q

What is electrophilic addition?

A

An alkene reacts with an electrophile; the double bond acts as a nucleophile.

30
Q

How are alkenes converted to alcohols?

A

React with water using an H₂SO₄ catalyst.

31
Q

How is ethanol produced industrially?

A

Ethene + steam at 300°C and 60 atm with solid phosphoric acid catalyst (reversible, low yield).

32
Q

Why is carbon dioxide a greenhouse gas?

A

It absorbs infrared radiation reflected from the Earth’s surface.

33
Q

What are the products of complete combustion of hydrocarbons?

A

Carbon dioxide and water.

34
Q

What are the products of incomplete combustion?

A

Carbon monoxide and water.

35
Q

Why is carbon monoxide dangerous?

A

It binds to haemoglobin, reducing oxygen transport in the blood.

36
Q

What do unburnt hydrocarbons and oxides of nitrogen cause?

A

Photochemical smog and ground-level ozone.

37
Q

How are nitrogen oxides formed?

A

From high pressure and temperature in car engines.

38
Q

What does sulfur dioxide do in the environment?

A

Forms sulfuric acid in moisture, damaging vegetation and buildings.

39
Q

What are particulates and why are they harmful?

A

Tiny airborne particles that can cause lung and cardiovascular issues.

40
Q

What do catalytic converters reduce?

A

Emissions of unburnt hydrocarbons, sulfur dioxide, and carbon monoxide.