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ib chemistry hl > 1 stoichiometric relationships > Flashcards

1 stoichiometric relationships Flashcards

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AP® Chemistry flashcards Periodic Table flashcards
1
Q

homogenous mixture

A

same composition/density throughout.

uniform.

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2
Q

heterogenous mixture

A

different composition/density throughout.

non-uniform

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3
Q

matter can either be

A

pure or a mixture

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4
Q

a pure substance can either be

A

an element or compound

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5
Q

a mixture can either be

A

homogenous or heterogenous

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6
Q

ideally do you want a high or low atom economy

A

high, meaning less waste

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7
Q

atom economy =

A

molecular mass of desired products
————————————————————- x 100
sum of molecular masses of all products

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8
Q

what atom economy would you expect from an addition reaction

A

100%

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9
Q

when is a low atom economy not bad

A

when you have uses for the waste products or can use them in industry

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10
Q

what atom economy would you expect from a substitution reaction

A

less than 100%

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11
Q

what atom economy would you expect from an elimination reaction

A

less than 100%

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12
Q

a high atom economy =

A

fewer waste materials

greener and more economical

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13
Q

percentage yield using moles =

A

moles of product obtained
——————————————- x 100
theoretical moles of product

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14
Q

percentage yield using mass =

A

mass of product obtained
——————————————————- x 100
maximum theoretical mass of product

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15
Q

SI for mass

A

kilograms (kg)

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16
Q

SI for thermodynamic temp

A

kelvin (K)

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17
Q

SI for luminous intensity

A

candela (cd)

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18
Q

masses of atoms are compared on a scale relative to…

A

12C

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19
Q

units of molar mass

A

g/mol

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20
Q

Ar =

A

1/12 mass of one atom of carbon-12

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21
Q

what is an ideal gas

A

one that follows the ideal gas equation and all gas laws.

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22
Q

what are real gases

A

all gases that deviate slightly from gas laws.

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23
Q

what happens to gas particles at a high pressure

A

they get closer together.

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24
Q

what happens to gas particles at low pressure

A

they move less rapidly (less KE) and spread out, leading to greater opportunity for intermolecular forces between the particles to have an effect

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25
Q

what is the ideal gas equation

A

PV = nRT

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26
Q

what is R in the ideal gas equation

A

8.314

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27
Q

what happens to ideal behaviour at low temps and high pressures

A

it behaves more like a real gas as particles move slower, so intermolecular forces become more significant

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28
Q

what happens to a real gas at low pressures and high temperatures

A

it behaves more like an ideal gas

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29
Q

what gases show the most ideal behaviour

A

those with a low molar mass and weak intermolecular forces between particles

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30
Q

what gases deviate from ideal behaviour the most

A

those with permanently polarized bonds or higher molar masses. this is because there are stronger intermolecular forces between the molecules. if they have strong hydrogen bonds, the deviation is even greater.

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31
Q

concentration def

A

the amount (in mol) or mass (in g) of solute per volume of solution.

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32
Q

units of concentration

A

mol dm-3,

g dm-3

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33
Q

concentration =

A

amount of volume

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34
Q

concentration =

A

volume (dm cubed)

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35
Q

ppm is

A

parts per million

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36
Q

what is a primary standard

A

high purity )99.9%)
high molar mass
low reactivity
does not change composition in contact with air

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37
Q

what is serial dilution

A

diluting a stock solution multiple times usually by the same factor

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38
Q

what is volumetric analysis

A

the precise measurement of volumes to calculate the concentration of a solution.

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39
Q

what is a titration

A

A titration is a method of volumetric analysis in which the concentration of a solution can be determined.

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40
Q

the titrant

A

a burette is filled with a standard solution of known concentration (the titrant)

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41
Q

what is analyte

A

A carefully measured volume of the solution with the unknown concentration (the analyte) is placed in a conical flask below the burette

42
Q

the first trial of a titration is

A

the rough titration

43
Q

what are concordant values

A

titration volumes within 0.10cm cubed of eachother

44
Q

what is a back titration

A

a technique which is useful for analysing impure substances. It is basically a titration done in reverse. In a back titration, an excess of titrant is added to the analyte and the excess titrant is then titrated to determine how much excess titrant remains. Back titrations are commonly used when one of the reactants is insoluble in water but does react with acid, an example being calcium carbonate.

45
Q

what is a standard solution

A

one of known concentration

46
Q

what is molar concentration

A

the number of moles of solute dissolved per litre of solution, i.e., M = mol/L

47
Q

moles =

A

conc x vol

48
Q

1dm cubed =

A

1000 cm cubed

49
Q

what is R

A

8.314

50
Q

what should p be in in the ideal gas equation

A

Pa

51
Q

what should V be in in the ideal gas equation

A

m cubed

52
Q

what should T be in in the ideal gas equation

A

kelvin

53
Q

cm cubed to m cubed

A

divide by 1000000 (10^6)

54
Q

dm cubed to m cubed

A

divide by 1000

55
Q

celsius to kelvin

A

+273

56
Q

kpa to pa

A

divide by 1000

57
Q

absolute zero

A

0 on kelvin

-273 celsius

58
Q

combination or synthesis reaction

A

when two or more substances react to produce a single product

59
Q

decompositon reaction

A

a single reactant being broken down into two or more products

60
Q

single replacement reactions

A

when one element replaces another in a compound. eg redox

61
Q

double replacement reactions

A

between ions in a solution to form insoluble substances and weak or non-electrolytes, also termed metatheiss reactions. eg acid base

62
Q

how to get from molecules to moles

A

divide by avogadros

63
Q

how to get from moles to molecules

A

multiply by avogadros

64
Q

isotopes

A

atoms of the same element that have the same number of protons but different numbers of neutrons

65
Q

relative abundance

A

measure fo how much of each isotope occurs in an element

66
Q

relative atomic mass

A

Ar

weighted average of the atomic masses of its isotopes and their relative abundances

67
Q

relative molecualr mass/relative formula mass

A

combining Ar values to form Mr

68
Q

molar mass

A

mass of one mole of a substance. g/mol

69
Q

qualitative analysis

A

determining which elements are present in a compound

70
Q

quantative analysis

A

determining the relative masses of elements

71
Q

how could reduced yield of products be caused

A

loss of products from reaction vessels
impurity of reactants
changes in reaction conditions like temp or pressure
reverse reactions consuming products in equilibrum systems
the existence of side reactions due to the presenve of impurities

72
Q

kinetic theory

A

most volume occupied by a gas is empty space
gaseous particles constantly move in straight lines but random directions
gaseous particles undergo elastic collisions with eachother and the container walls. no loss of KE
gaseous particles exert no force of attraction on other gases

73
Q

stp vokme

A

22.7 dm^3 mol^-1

74
Q

boyles law

A

V1p1 = V2p2

75
Q

charles law

A

V1 V2
—– = ——-
T1 T2

76
Q

gay-lussac law

A

p1 p2
—- = —–
T1 T2

77
Q

combined gas law

A

p1V1 p2V2
——– = ——–
T1 T2

78
Q

ideal gas equation

A

pV = nRT

79
Q

why do gases deviate from the ideal gas law at high pressures

A

molecules have finite volume

80
Q

volume and pressure are……. in a fixed mass of an ideal gas

A

inversely proportional .

81
Q

is sublimation exo or endothermiv

A

endothermic

82
Q

is evaporation exo or endothermic

A

endothermic

83
Q

is condensation exo or endothermic

A

exothermic

84
Q

avogadro’s law

A

V1 V2
—– = ——
n1 n2

85
Q

how do you find the limitign reagent

A

calculate moles and then divide by coefficent

86
Q

1 molecule’s mass =

A

Mr

  1. 022 x 10^23
87
Q

for reactions of gases, what cna you use instead of the molar ratio

A

the volume ratio

88
Q

1 ppm =

A

1 mg/dm cubed

89
Q

1mg =

A

0.001 grams

90
Q

pressure =

A

V

91
Q

how do you get from atoms to moles

A

divide by avogadros

92
Q

what is aboslute temperature proportional to

A

kinetic energy

93
Q

what is Mr/other names

A

sum of Ar / sum of relative atomic masses

relative formula mass
relative molecular mass

94
Q

moles to grams

A

multiply by molar mass

95
Q

grams to moles

A

divide by molar mass

96
Q

how to calculate molecualr formula

A

empirical formula Mr

then multiply everythign in the empirical formula by that factor

97
Q

molar conc =

A

volume of solution

98
Q

standard solution is when

A

the precise conc is known

99
Q

what is avogadros law

A

equal volumes of gases at the same temp and pressure contain equal numbers of particles

100
Q

which gases show themost ideal behavour

A

low molar mass

weak intermolecular forces between particles

ib chemistry hl (12 decks)

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