AS physical + tests Flashcards

1
Q

Test for ammonium

A
  1. Add Warm NaOH
  2. heat gently
  3. place damp red litmus above

Result - red litmus turns blue

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2
Q

Test for carbonates

A
  1. Add diluted HCl (aq)
  2. Collect gas produced
  3. bubble through limewater

Result - limewater goes milky

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3
Q

Test for sulphate

A
  1. Add barium nitrate
    Result - form white p.p.
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4
Q

Test for halides

A

Add silver nitrate
Result :
Chlorine - white p.p.
Bromine - cream p.p.
Iodine - yellow p.p.

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5
Q

How to identify the halide test result better

A

Add diluted ammonia sol. to the p.p.
Chlorine - dissolve in dil. NH3
Bromine - dissolve in conc. NH3
Iodine - remains insoluble

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6
Q

enthalpy change

A

the change in heat content of a system during a reaction

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7
Q

enthalpy change of combustion

A

the enthalpy change when 1 mole of a subtance is completely combusted

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8
Q

enthaply change of formation

A

the enthalpy change when 1 mol of a compound is formed from its element

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9
Q

enthalpy change of neutralisation

A

the enthalpy change when 1 mol of water is formed from a neutralisation reaction

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10
Q

Activation energy

A

the minimum energy required for a reaction to take place

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11
Q

Average bond enthalpy

A

the energy required to break 1 mol of GASEOUS bonds

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12
Q

Endothermic

A

E(Bonds breaking) > E(bond making)
takes in energy from surrounding

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13
Q

Exothermic

A

E(Bond breaking) < E(bond making)
releases energy to surronding

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14
Q

Standard conditions

A

100 kPa and 298K

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15
Q

Hess’s law

A

the enthalpy change of a reaction is independent of the route it takes

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16
Q

Bond dissociation energy

A

Amount of energy used to break 1 mol of specific covalent bond in gaeous state

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17
Q

General eq for ΔHf
enthalpy change of formation

A

Elements -> compound

20
Q

Collision theory

A

the theory which states that molecules must collide with:

  1. sufficient energy ( energy > Ea)
  2. at the correct orientation

for a reaction to occur

21
Q

hetrogenenous catalyst

A

Catalyst in a DIFFERENT state to reactant

22
Q

Homogenenous catalyst

A

Catalyst in the SAME state to reactant

23
Q

Collision frequency

A

no. of collision per given time

24
Q

3 factors that affects rate

A
  1. Temp.
    2.Conc.
    3.Pressure
25
benefits of catalyst in economic terms
1. ↓temp and Pa needed 2. ↓ CO2 emission 3. ↓lower fuel demand 4. ↓lower economic cost
26
3 methods to record rates
1. Volume of gas produced (/time) 2. change in mass (/time) 3. time for dissapearance/ colour change
27
What are the axises for Boltzman's distribution?
y - no. of particles x- the energies
28
What 3 factors have no effect on Boltzman's districution? Why?
Pressure, concentration and surface area 1. It increase Frq. of successful collision 2. No effect to energies of individual molecules 3. No change to shape of curve
29
Effect of temperature increase to Boltzman's curve
SHIFTS RIGHT ↑ % of molecules have energies >= Ea
30
Effects of Catalyst on Boltzman's distribution
1. ↓ Ea 2. No affect of energies of individual molecules 3. 3. ONLY greater % of molecules with energies >= Ea
31
Homogeneous equilibrium
An equilibrium in which all reactants are in the **same** state
32
Dynamic equilibrium
A closed system in which * rates of foward and reverse reaction are the same * Conc. of reactant and product are constant
33
Le chatellier's principal
When a system in dynamic eqm is subject to change, the position of eqm will shifts to oppose the change.
34
Factors that affects position of eqm
Temp., Pressure, Conc. NOT catalyst as it ↓ Ea for both foward and reverse
35
E.g Le Chatelier principal Q: Effect on position of Eqm when temp increases?
Shifts to endothermic
36
E.g Le Chatelier principal Q: Effect on position of Eqm when pressure increases?
Shifts to side with ↓ gas moles
37
E.g Le Chatelier principal Q: Effect on position of Eqm when c(Product) increases?
Shifts to favor reactant (LHS)
38
3 optimal conditions for haber process | N2+3H2 ⇌ 2NH3
1. ↑ pressure ( less gas moles on the right) 2. ↓ temp. (Foward reaction is exo.) 3. ↑ c( N2 + H2) and low c(NH3)
39
What are the comprimise to conditions for reactions ?
Need to comprimise between 1. Rate + time consumption 2. Eqm - % yield 3. safety (↑Pa - dangerous) 4. cost (↑temp - ↑ cost for fuel) 5. ↓PA - Rates maybe too slow
40
Indication when Kc = 1
conc(reactant) = conc(Product) eqm at the centre
41
Indication when Kc < 1
conc(reactant) > conc(Product) eqm to LHS
42
Indication when Kc >1
conc(reactant) < conc(Product) eqm to PHS