exam Flashcards

1
Q

primary standard solution

A

a solution containing one solute, prepared by dissolving a known mass of that solute in a known volume of water. As a result the concentration is known accurately

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2
Q

primary standard

A

a substance that can be prepared pure and dissolved in water to make a solution whose concentration is accurately known

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3
Q

where are the strongest oxidants on the electrochemical series

A

top left (at cathode)

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4
Q

rules for ox number

A

F = -1
H to non-metals is +1, H to metals is -1
Oxygen in peroxides is -1

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5
Q

salt bridge function

A

contain free-moving unreactive ions that keep polarity/charge constant

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6
Q

cell potential

A

E (cathode) - E (anode)

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7
Q

water properties

A

high latent heat
high specific heat capacity
high melting and boiling point
universal sovent

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8
Q

why does water expand upon freezing

A

as cools, molecules slow down and water adopts more regular lattice bc rigid H bonds bw molecules
this -> hexagonal lattice as ice pushes molecules further apart vs liquid form, expanding liquid water
tf same no of molecules occupy larger space and ice has a lower density

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9
Q

latent heat of fusion

A

nrg required to convert 1 mol of substance from s to l at its melting point

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10
Q

latent heat of vaporisation

A

nrg required to convert 1 mol of substance from l to g as it’s boiling point

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11
Q

specific heat capacity

A

amount of nrg required to raise the temp of 1g of substance by 1 degree C
Q=mcAT

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12
Q

process of dissolving

A

forces being formed need to be approximately the same strength or stronger than forces being broken
“bonds being formed are weaker than those that were broken tf immiscible”

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13
Q

insoluble ions

A

halides w Ag, Pb, Hg
SO4 w Pb or Ba
O, S, CO3, PO4 except for G1
OH except G1, Ba or Ca

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14
Q

ppm

A

mg/L or ug/g

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15
Q

w/w%
w/v%
v/v%

A

g/g
g/mL
mL/mL

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16
Q

crystallisation

A

solid crystals form as temp decreases and the solute can no longer remain dissolved. the slower the cooling, the bigger the crystals

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17
Q

Kw - ionic product of water

A

[OH][H3O] = 10 ^-14

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18
Q

ph

A

-log [H]; 14 + log[OH]
10 ^-pH; 10 ^pH-14

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19
Q

assumption with diprotic acids

A

assume all molecules eg H2SO4 dissociate and all hydrogen ions contribute to pH

20
Q

Ka (weak acids)

A

[H+]^2 / [acid]

21
Q

collision theory

A

for a chemical reaction to occur, reactant particles need to collide with sufficient nrg and the correct orientation

22
Q

factors affecting the rate of reaction

A

increase fq of successful collision:
SA of solid
concentration of solution
pressure (by decreasing volume)(Boyle’s law)
increase proportion w nrg > = Ea
temperature
catalysts (reduce Ea)

23
Q

dynamic equilibrium

A

rate of forward reaction = rate of reverse reaction

24
Q

Le Chatelier’s Principle

A

system at equilibrium has a tendency to partially oppose a change

25
Q

orbital

A

region of space in which up to 2 e are likely to be located. Orbitals may also be empty

26
Q

Pauli’s Exclusive Principal

A

a max of 2 e in a given orbital of opposite spins

27
Q

Hund’s Rule of Maximum Multiplicity

A

every orbital in a sub shell is half-filled before any orbital in that subshell is filled

28
Q

Aufbai=u Principal

A

subshells are filled in order from lowest to highest nrg

29
Q

electron configuration exceptions

A

Chromium and Copper

30
Q

cc

A

measure of net attractive force felt by valence e towards the nucleus
protons- inner shell e

31
Q

electronegativity

A

strength with which atoms of an element attract electrons when they are chemically combined with another element

32
Q

ionisation nrg

A

amount of nrg required to remove an electron from 1 mol of a gaseous atom

33
Q

mettalic bonding

A

electrostatic force of attraction in lattice between sea of delocalised e and positively charged cations

34
Q

covalent bonding

A

shared pair of e bw two non-metal ions

35
Q

dative covalent bond

A

both of shared electrons are contributed by one atom only

36
Q

fuel

A

substance that burns in air or oxygen to release a usable amount of nrg

37
Q

substitution reaction (alkanes)

A

UV light

38
Q

haloalkane + OH –>

A

alcohols

39
Q

alkene + hydrogen

A

Ni catalyst + 150C

40
Q

alkene + water

A

(steam) H3PO4, 300C, 60-70atm

41
Q

thermoplastic

A

no cross-links
chains loosely tangled together
low mp
can be remoulded
eg plastic bags/cling wrap

42
Q

thermosetting

A

cross-link bw chains
rigid and inflexible
X be remoulded
eg kitchen bench cover

43
Q

elastomers

A

can be stretched/deformed
retain their shape
few cross-links

44
Q

polymerisation

A

under pressure w catalyst

45
Q

LDPE

A

Low density polyethene:
high temp and pressure
amorphous (branched chains that don’t fit well)
low mp
soft and flexible
eg carrier bags, plastic wrap

46
Q

HDPE

A

high density polyethene:
cataylst at lower temp
unbranched chains that fit together
more cyrstalline and less amorphous
eg wheelie bins. classroom chairs