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Chemistry A Level > Random Shit > Flashcards

Random Shit Flashcards

1
Q

What differences in physical properties can isotopes have?

A

Higher mass isotopes =
• higher m.p. + b.p.
• higher density

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2
Q

What’s the mass of an electron?

A

1/1836

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3
Q

Define conjugate acid-base pair

A

2 species differing by H+

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4
Q

Assumptions made for weak acids

A

• [H+] = [A-]

  • Breakdown of H2O = neg
  • for every [HA] breakdown -> 1 [H+] + 1 [A-]
  • except v.weak acids/v.dilute ∵ H20 breakdown = sig

• [HA]equi = [HA]start

  • ∵ [HA]start»[H+]equi
  • so little [HA] breakdown ∴ = neg
  • except ka> x 10-2/v.dilute
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5
Q

Methyl orange range

A

3-4 pH

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6
Q

Phenolphthalein

A

8-10 pH

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7
Q

Standard electrode potential

A

E.m.f. of a half cell compared to a H half cell

State the standard conditions

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8
Q

How does ligand substitution allow haemoglobin to transport O2 in blood

A

O2 bonds to Fe2+

When required O2 is substituted

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9
Q

How can an aq solution of an acid contain -OH

A

Water dissociates

H2O -> H+ + -OH

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10
Q

Give 2 reasons why it is uncertain whether reactions predicted from E values may acc take place

A

Conditions not standard

High Ea/slow rate

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11
Q

Suggest why methanol is added to petrol

A

It adds O2

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12
Q

Deduce feasibility of a reaction based on electrode potential

A

If overall cell potential > +0.40V = likely
>0.00 = feasible
< 0.00 = not feasible

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13
Q

Explain in terms of equi why cell potential increase E.g. Cu2+ + 2e -> Cu
If water is added

A
  • H2O reacts w/ Cu2+ ∴ [Cu2+] decreases + equi shifts to left
  • more e released by Cu
  • cell has bigger difference in E/more negative
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14
Q

Explain in terms of electrode potentials why Cr is more reactive than Cu

A
  • E for Cr is more negative

* Cr shifts left and Cu shifts right

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15
Q

In presence of CO, less O2 is transported in the blood. Suggest why in terms of stability constants

A

W/ CO stability constant > than O2

∴ bond w/ CO is stronger

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16
Q

Describe action if platin in treatment of cancer patients

A

Stops cancer cells from replicating

17
Q

What important factors should you consider when deciding the most suitable indicator

A
  • vertical section match pH range
  • colour change
  • end point
18
Q

2 advantages of using fuel cells compared w/fossil fuels

A
  • greater efficiency

* less greenhouse gases/only H2O formed

19
Q

1 adv of using methanol than H in a fuel cell

A
  • liquid ∴ easier to store/transport

* give a greater cell potential

20
Q

Describe bonding in water

A

H bonds between H + lone pair

21
Q

Describe the relative energies of 2s orbitals and each of the three 2p orbitals in a nitrogen atom

A

P orbital E > s orbital

P orbitals are equal in E

22
Q

Why do some people consider use of H uses more energy than fossil fuels

A

E required to produce H

23
Q

Difference between fuel cell + conventional electrochemical cell

A

Fuel cell converts E from reaction of fuel + O2

24
Q

Salt

A

When H atom/s in an acid is replaced w/a metal ion/+ve ion

25
Q

Right equations for the reaction of chlorine and cold, dilute sodium hydroxide

A

Cl2 + 2NaOH -> NaClO + NaCl + H2O

26
Q

Write the equation for the reaction of chlorine and hot concentrated sodium hydroxide

A

Cl2 + 6NaOH -> NaClO3 + 5NaCl + 3H2O

27
Q

Why is the reaction between chlorine + water limited and how do you overcome this

A

Limited by the low solubility of chlorine in water

Dissolve NaOH in water

28
Q

Suggest why there are no other intermolecular forces in solid sulphur

A

Only one type of atom

29
Q

Why is the enthalpy change of hydration of chloride ions exothermic

A

Hydration involves bond forming

30
Q

Explain why x can react spontaneously even though the process is endothermic

A
  • Entropy/disorder increases
  • so H-TS is negative

Or

• calculated G = negative / < 0

31
Q

Explain how electron pairs = prediction of shape

A

Pairs of e repel

Ratio of lone:bonded helps determine

32
Q

Explain how the choice of indicator is linked to pH curve

A

Using vertical section

pH range should match vertical section

33
Q

Explain why something would have a permanent dipole

A

Difference in electronegativity

DIPOLES DO NOT CANCEL ∵ asymmetric

34
Q

What makes a d block element

A

D is the highest E subshell

35
Q

What 2 factors affect rate constant

A

1) increasing T shifts Boltzmann distribution to the right ∴ increasing proportion of P that excess Ea
2) P move faster and collide mor frequently

36
Q

What’s a ppt reaction

A

When 2 aw solutions containing ions react together to form an insoluble ionic solid

37
Q

Suggest why complex ions w/ partially filled d sub levels are coloured

A

Electrons are excited and absorb E from light

38
Q

2 disadvantages of using fuel cells over conventional

A

1) H2 difficult to store

2) limited life cycle of H adsober/absorber

Chemistry A Level (25 decks)

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