Developing Fules Flashcards Preview

A-Level Chemistry [OCR B] > Developing Fules > Flashcards

Flashcards in Developing Fules Deck (50)
Loading flashcards...
1

[DF1] What is the ideal gas equation?

pV = nRT

p: pressure (Pa)
V: volume (m³)
n: number of moles (mol)
R: gas constant (8.313 J mol⁻¹ K⁻¹)
T: tempreture (K)

2

[DF1] How can you predict the yield of a reaction?

(e.g. 4Na + O₂ → 2Na₂O)

- Work out the number of moles of a reactant you have used.
(for 2g of Na: 2/23 = 0.087 mol)

- Multiply by the ratio between the chosen reactant and product.
(0.087 x 0.5 = 0.044 mol)

- Multiply by the Mᵣ of the product.
(0.044 x 62 = 2.73g)

3

[DF2] What is the difference between a π bond and a σ bond?

A σ bond is caused by the direct overlap of the p-orbitals or carbon atoms.

π bonds are caused by the indirect 'leaning overlap of p-orbitals.

https://drive.google.com/file/d/1SoOShMkBMVTeTVWXH3FekXELkqsEf-dH/view?usp=sharing

4

[DF2] What is a double bond?

A double bond consists of one π bond and one σ bond.

5

[DF2] How can you draw a molecule in 3D?

- A solid line represents a bond in the plane of the paper.

- A solid wedge represents a bond coming out of the plane of the paper.

- A dashed/dotted wedge represents a bong going into the plane of the paper.

6

[DF3] What is the meaning of the term 'endothermic'?

- Endothermic reactions are those that take energy in from the surroundings:

- The energy needed to break the bond is greater than the energy needed to make the bond in the reaction.

7

[DF3] What is the meaning of the term 'exothermic'?

- Exothermic reactions are those that release energy into the surroundings:

- The energy needed to break the bond is less than the energy needed to make the bond in the reaction.

8

[DF3] What are standard conditions?

- A pressure of 100kPa (1atm)

- A temperature of 298K (room temperature)(25⁰C)

- All solutions are at a concentration of 1 mol dm⁻³ for electrode potentials.

9

[DF3] Define the standard enthalpy change of reaction, ΔHᵣᶿ.

The enthalpy change that occurs when substances are reacted in the molar ratios as defined by a chemical equation.

The reaction takes place under standard conditions with reactants and products in their standard states.

10

[DF3] Define the standard enthalpy change of combustion, ΔH꜀ᶿ.

The enthalpy change that occurs when substances are reacted with one mole of oxygen.

The reaction takes place under standard conditions with reactants and products in their standard states.

11

[DF3] Define the standard enthalpy change of formation, ΔHғᶿ.

The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

12

[DF3] Define the standard enthalpy change of formation, ΔHₙₑᵤₜᶿ.

The enthalpy change that occurs when one mole of water is produced from a neutralisation reaction that happens under standard conditions.

13

[DF3] What is average bond enthalpy?

The energy needed to break one mole of the standard bond under standard conditions.

14

[DF3] What relation does bond enthalpy have to bond strength?

The greater the bond enthalpy, the greater the bond strength.

As the bond strength increases the length of the bond decreases.

15

[DF3] Match the reaction process to the thermal result:

- Bond breaking.
- Bond making.

- Exothermic.
- Endothermic.

- Bond breaking = Endothermic.

- Bond making = Exothermic.

16

[DF3] What does each term mean in q = mcΔT

q = mcΔT

q: The energy absorbed by the material (normally water) (J)
m: The mass of material being used (g)
c: The specific heat capacity of the material used (c of water = 4.18 Jg⁻¹K⁻¹)
ΔT: The change in temperature of the material (final - initial)

17

[DF4] What is a catalyst?

- A catalyst is a substance that is not used up in the reaction.

- And helps to increase the rate of reaction by offering a different pathway for the reaction to take.

18

[DF4] What is catalyst poison?

A substance that reduces the effectiveness of the catalyst by permanently bonding to the active site.

19

[DF4] What does heterogeneous mean?

- A heterogeneous catalyst is one that does not share the same phase as the reactants.

- For example the solid iron catalyst in the gaseous reaction of hydrogen and nitrogen.

20

[DF4] What does heterogeneous catalysis look like?

- The reactants form partial bonds with the catalyst, adsorbing onto the surface.

- Because the reactants are in close proximity, successful collisions are more frequent.

21

[DF4] What is cracking?

The breaking of long-chain alkanes into shorter-chain alkanes and alkenes.

22

[DF5] What are some common simple molecular pollutants?

- CO.
- CO₂.
- NOₓ.
- SOₓ.
- unburnt hydrocarbons.

23

[DF5] What are some methods of reducing CO₂ emissions?

Using renewable sources of electricity such as solar or wind power as well as using electric or hydrogen-powered cars can be methods of reducing CO₂ emissions.

24

[DF5] What are some methods of reducing CO and unburnt hydrocarbons?

Using more efficient engines and catalytic converters in cars.

25

[DF5] How can NOₓ and SOₓ emissions be reduced

Modifications to engines and the fuels used can reduce NOₓ and SOₓ emissions.

26

[DF6] What is an aromatic hydrocarbon?

A hydrocarbon that contains benzene (or other aromatic) ring.

27

[DF6] What is an aliphatic hydrocarbon?

A hydrocarbon that does not contain any aromatic rings and is a straight or branched chain hydrocarbon

28

[DF6] What is a saturated hydrocarbon?

A hydrocarbon which contains only single carbon-carbon bonds.

29

[DF6] What is an unsaturated hydrocarbon?

A hydrocarbon which contains one or more carbon=carbon double bond.

30

[DF6] What is a homologous series?

A group of hydrocarbons with the same functional group and thus the same general formula.

(each successive member differs by CH₂.)