DF Flashcards

1
Q

Is bond making/breaking endothermic or exothermic?

A

Breaking - endothermic
Making - exothermic

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2
Q

What is standard enthalpy change of neutralisation?

A

1 mol of H+ reacts with 1 mol OH- to form 1 mol of H2O

1moldm-3 conc

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3
Q

What is a homologous series?

A

Compounds that differ by -CH2

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4
Q

Why would temperature change be inaccurate for endothermic processes?

A

Heat taken in

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5
Q

Why do diesels produce less hydrocarbons?

A

Less volatile / higher bp

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6
Q

Why could enthalpy change of combustion be different to a book value?

A

Bond enthalpy is an average
Not in standard states

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7
Q

What is enthalpy change of combustion?

A

1 mole completely burned in oxygen

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8
Q

What is enthalpy of formation?

A

1 mole of compound formed from its elements

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9
Q

Which way do the arrows go on a
Formation cycle
Combustion cycle?

A

Outwards
Inwards (to CO2 + H2O)

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10
Q

Chain isomer

A

Different arrangement of carbon skeleton (branching)

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11
Q

Positional isomer

A

Different position of functional group

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12
Q

Functional group isomer

A

Different functional group

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13
Q

Conditions + product of hydrating alkenes

A

300c
60 atm
Steam + acid catalyst
Alcohol

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14
Q

What causes photochemical smog?

A

Unburnt HC (C) and NOx

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15
Q

What causes acid rain?

A

SO2
NOx

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16
Q

Disadvantages of biofuels

A

Expensive
Land used to grow crops instead

17
Q

What is a sigma bond?

A

Overlap of s-orbitals
Free rotation

18
Q

What bonding is found in single bonds?

A

Sigma

19
Q

What bonds are found in a double bond?

A

One sigma and one pi bond

20
Q

What is a pi bond?

A

Overlap of p-orbitals

21
Q

What is standard enthalpy change of formation?

A

One mol of substance formed from its elements

22
Q

What is standard enthalpy change of combustion?

A

One mol of substance burnt completely in oxygen

23
Q

What are the 4 steps of heterogenous catalysis?

A

Reactants adsorb to catalyst surface
Bonds weaken/break
New bonds formed between reactants
Product desorbs from catalyst surface

24
Q

Equation for enthalpy change

A

break + make
(+) + (-)

25
Q

What is the definition of bond enthalpy?

A

The energy required to break one mole of the bond in gaseous state under standard conditions

26
Q

What is specific heat capacity?

A

Energy required to raise 1g of substance by 1K without a change of state

26
Q

Calorimetry graph

A

Temp/time

27
Q

How do you calculate enthalpy change per mole?

A

Q/moles

28
Q

What is thermal cracking?

A

High temperature and pressure

29
Q

What is catalytic cracking?

A

Produces aromatic compounds with carbon rings
Lower temp (720K)
Normal pressure

Hydrocarbon vapour passed over heated catalyst

30
Q

What are the effects of CO?

A

Toxic –> suffocation

31
Q

What are the effects of NOx/SOx?

A

Acid rain

32
Q

What are the effects of carbon particulates?

A

Respiratory problems
Global dimming

33
Q

What is a catalytic converter made from?

A

Rhodium

34
Q

What is an arene?

A

Aromatic
Contains benzene as part of structure

35
Q

What is an aliphatic compound?

A

No benzene

36
Q

Why is the enthalpy same for isomers?

A

Same number and same type of bonds broken

37
Q

Why may enthalpy change be different? NOT LOWER

A

Not standard states
Bond enthalpy is an average

38
Q

What is an explanation of Hess’ law?

A

energy change independent of route
as long as conditions remain the same