Random Shit

Question 1

What differences in physical properties can isotopes have?

Answer 1

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

Question 2

What’s the mass of an electron?

Answer 2

1/1836

Question 3

Define conjugate acid-base pair

Answer 3

2 species differing by H+

Question 4

Assumptions made for weak acids

Answer 4

• [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

Question 5

Methyl orange range

Answer 5

3-4 pH

Question 6

Phenolphthalein

Answer 6

8-10 pH

Question 7

Standard electrode potential

Answer 7

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

State the standard conditions

Question 8

How does ligand substitution allow haemoglobin to transport O2 in blood

Answer 8

O2 bonds to Fe2+

When required O2 is substituted

Question 9

How can an aq solution of an acid contain -OH

Answer 9

Water dissociates

H2O -> H+ + -OH

Question 10

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

Answer 10

Conditions not standard

High Ea/slow rate

Question 11

Suggest why methanol is added to petrol

Answer 11

It adds O2

Question 12

Deduce feasibility of a reaction based on electrode potential

Answer 12

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

Question 13

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

Answer 13

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

Question 14

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

Answer 14

• E for Cr is more negative

* Cr shifts left and Cu shifts right

Question 15

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

Answer 15

W/ CO stability constant > than O2

∴ bond w/ CO is stronger

Question 16

Describe action if platin in treatment of cancer patients

Answer 16

Stops cancer cells from replicating

Question 17

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

Answer 17

• vertical section match pH range
• colour change
• end point

Question 18

2 advantages of using fuel cells compared w/fossil fuels

Answer 18

• greater efficiency

* less greenhouse gases/only H2O formed

Question 19

1 adv of using methanol than H in a fuel cell

Answer 19

• liquid ∴ easier to store/transport

* give a greater cell potential

Question 20

Describe bonding in water

Answer 20

H bonds between H + lone pair

Question 21

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

Answer 21

P orbital E > s orbital

P orbitals are equal in E

Question 22

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

Answer 22

E required to produce H

Question 23

Difference between fuel cell + conventional electrochemical cell

Answer 23

Fuel cell converts E from reaction of fuel + O2

Question 24

Salt

Answer 24

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

Question 25

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

Answer 25

Cl2 + 2NaOH -> NaClO + NaCl + H2O

Question 26

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

Answer 26

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

Question 27

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

Answer 27

Limited by the low solubility of chlorine in water

Dissolve NaOH in water

Question 28

Suggest why there are no other intermolecular forces in solid sulphur

Answer 28

Only one type of atom

Question 29

Why is the enthalpy change of hydration of chloride ions exothermic

Answer 29

Hydration involves bond forming

Question 30

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

Answer 30

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

Or

• calculated G = negative / < 0

Question 31

Explain how electron pairs = prediction of shape

Answer 31

Pairs of e repel

Ratio of lone:bonded helps determine

Question 32

Explain how the choice of indicator is linked to pH curve

Answer 32

Using vertical section

pH range should match vertical section

Question 33

Explain why something would have a permanent dipole

Answer 33

Difference in electronegativity

DIPOLES DO NOT CANCEL ∵ asymmetric

Question 34

What makes a d block element

Answer 34

D is the highest E subshell

Question 35

What 2 factors affect rate constant

Answer 35

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

Question 36

What’s a ppt reaction

Answer 36

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

Question 37

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

Answer 37

Electrons are excited and absorb E from light

Question 38

2 disadvantages of using fuel cells over conventional

Answer 38

1) H2 difficult to store

2) limited life cycle of H adsober/absorber