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topic one Flashcards

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1
Q

what are the three states of matter

A

solid, liquid, gas.

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2
Q

what is plasma

A

ionised gas mainly found in outer space. it can be referred to as the fourth state

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3
Q

what is kinetic energy

A

the energy related to the motion or movement of an object.

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4
Q

how are the different physical states characterised

A

by the different arrangement and movement of the particles. this is dependent on the amount of kinetic energy that the particles possess.

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5
Q

properties of a solid

A
  1. particles closely packed
  2. strong forces between particles, they vibrate around fixed positions
  3. fixed shape
  4. fixed volume
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6
Q

properties of a liquid

A
  1. particles more spread out
  2. Weaker forces between particles, they can move past each other
  3. take the shape of container
  4. fixed volume
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7
Q

properties of a gas

A
  1. particles very spread out
  2. neglibile forces between particles, they move randomly
  3. no fixed shape
  4. no fixed volume
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8
Q

what are changes of state at constant pressure directly related to

A

change in temperature.

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9
Q

describe the effect of an increase in temperature on a substance

A

increases the average kinetic energy which means the particles are able to overcome the intermolecular forces that exist between them, which results in a change of state.

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10
Q

what is the process of gas to solid

A

deposition

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11
Q

what is the process of solid to gas

A

sublimation

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12
Q

is energy released or absorbed in sublimation

A

absorbed

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13
Q

is energy released or absorbed in deposition

A

released

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14
Q

when does the temperature stay constant during a temperature curve

A

when melting and boiling.

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15
Q

why does temperature stay constant during melting and boiling.

A

At these points, the energy is being used to overcome the intermolecular forces that exist between the particles.

During melting, the energy input is being used to overcome the intermolecular forces that hold the particles in the solid in fixed positions.

During boiling, the energy input is being used to overcome the intermolecular forces that hold the particles in the liquid together.

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16
Q

what is density

A

mass per unit volume

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17
Q

density =

A

mass / volume

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18
Q

what are elements made of

A

the same kind of atom and cannot be broken down into simpler substances by chemical means

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19
Q

what is an atom

A

the smallest particle that shows the characteristic properties of that element.

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20
Q

what are metalloids

A

have the properties of both metals and non metals

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21
Q

elements combine in chemical reactions to make…

A

compounds

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22
Q

what is a compound

A

made up of two or more different elements that are chemically combined

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23
Q

sodium chloride is

A

a white solid

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24
Q

describe hydrogen gas

A

explosive

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25
Q

describe oxygen gas

A

highly reactive

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26
Q

define molecule

A

two or more atoms that are chemically bonded together.

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27
Q

why is NaCl a formula unit

A

tells us the lowest whole number ratio of the two elements that make up the compound.

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28
Q

homogenous

A

same composition throughout

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29
Q

heterogenous

A

non uniform composition

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30
Q

despite homogenous mixtures not being chemically combined

A

they do not seperate physically on standing

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31
Q

what is air composed of

A

nitrogen, oxygen, argon

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32
Q

as each component in air has its own boiling point, the gases can be seperated by

A

fractional distillation

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33
Q

composition of air

A

nitrogen 78%
oxygen 20.9%
argon 0.93%
carbon dioxide 0.04%

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34
Q

are solutions homogenous or heterogenous

A

homogenous

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35
Q

what is the concentration of the solution

A

the amount of solute dissolved in a known volume of a solution

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36
Q

what is the resultant volume

A

the final volume

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37
Q

what is crude oil

A

complex mixture of hydrocarbons (compounds containing only carbon and hydrogen)

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38
Q

chemical reactions involve the formation of new

A

chemical substances

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39
Q

why must the number and dtype of each atom be the same in the reactants and products

A

due to the conservation of mass.
mass must be conserved in a chemical reaction.

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40
Q

The numbers in front of each formula in a balanced equation are called

A

stoichiometric coefficients

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41
Q

what do stoichiometric coefficients tell us

A

the molar ratios of reactants

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42
Q

commmon (s)

A

Na (s), Mg (s), C (s)

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43
Q

common (l)

A

H2O (l), Br2 (l)

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44
Q

common (g)

A

O2 (g), CO2 (g)

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45
Q

common (aq)

A

NaCl (aq), H2SO4 (aq)

46
Q

what is a precipitate

A

an insoluble solid that forms out of a solution

47
Q

on a relative scale, what is carbon 12 assigned the weight of?

A

12

48
Q

what does Ar mean

A

relative atomic mass, the weighted average mass of an atom compared to 1/12 the mass of an atom of carbon-12.

49
Q

the mass of 1/12 of an atom of carbon12 is known as an

A

atomic mass unit

50
Q

what does a mixture of isotopes make up

A

any natural sample of an element

51
Q

an isotope has a different number of

A

neutrons

52
Q

how can you analyse the abundance of isotopes of an element

A

using a mass spectrometer

53
Q

what is relative atomic mass calculated from

A

a weighed average that takes into account the existence of different isotopes and their relative abundance.

54
Q

why is carbon 12 used as a reference

A

it can be accurately measured and is the most abundant stable isotope of carbon

55
Q

The relative formula (or molecular) mass (Mr) of a compound is

A

the weighted average mass of the compound compared to 1/12 the mass of an atom of carbon-12.

56
Q

why is 1/12 of carbon12 used

A

each amu is 1, so carbon 12 has 12 amu

57
Q

what is the mole

A

the SI unit for the amount of substance (n)

58
Q

the number of particels in a mole of a substance is numerically equal to the

A

Avogadro’s constant, 6.02 × 10^23 mol-1

59
Q

what is molar mass

A

the mass of one mole of a substance

60
Q

what is molar mass numerically equal to

A

relative atomic mass

61
Q

empirical formula

A

the lowest whole number ratio of atoms or ions in a compound. a molecular formula is the actual number of atoms in a compound

62
Q

molecular formula

A

the actual number of atoms in a compound

63
Q

when is the empirical formula equal to the molecular

A

for all ionic compounds

64
Q

how to calculate empirical formula

A

from the percentage, divide by molar mass to find the amount in moles. find the simplest whole number ratio.

65
Q

percentage composition formula

A

mass of element in compound / molar mass of compound x 100%

66
Q

empirical formulas can be found experimentally via…

A

experimental data
water of crystallisation
combustion analysis

67
Q

when are molar ratios useful

A

to determine limiting and excess reagents

68
Q

what is the limiting reactant

A

limits the amount of product that can be produced.

69
Q

what is the excess reactant

A

the amount that remains once the limiting reactant has been consumed in the reaction

70
Q

when determining limiting and excess reactants, what is divided by what

A

the amount in moles is divided by the molar ratio/coefficent

71
Q

what is the theoretical yield

A

the max amount of product that can be produced assuming that all the limiting reactant has reacted.

72
Q

what is the actual yield

A

the amount of product actually produced in a chemical reaction

73
Q

percentage yield

A

actual / theoretical x 100%

74
Q

the kinetic molecular theory of gases

A

The particles in a gas are in constant, random, straight-line motion.
There are negligible forces of attraction (intermolecular forces) between the particles.
Collisions between particles or with the walls of the container are perfectly elastic (no energy is lost).
The distance between the particles is much greater than the size of the particles, therefore, gas particles have negligible volume.
The kinetic energy of the particles in a gas is directly proportional to the absolute temperature (in kelvin).

75
Q

the pressure exerted by a gas in a container is determined by how

A

frequently the particles hit the walls of the container

76
Q

what is avogadro’s law

A

equal volumes of gases at the same temperature and pressure contian equal numbers of particles.

77
Q

molar volume of a gas

A

This states that one mole of a gas at STP occupies a volume of 22.7 dm3 (22700 cm3 or 0.0227 m3).

78
Q

relationship between the amount of a gas (in mol) and its volume

A

amount in mol = vol (dm^3) / molar vol (22.7dm^3)

79
Q

an ideal gas is

A

a gas that exhibigts the five postulates of the kinetic molecular theory, as well as obeying gas laws.

80
Q

what are the gas laws

A

Boyle’s law, Charles law, Gay-Lussac’s Law

81
Q

what temperature scale must you use for gas laws

A

kelvin.

82
Q

Boyles law

A

at constant temperature the pressure and volume of a fixed mass of an ideal gas are inversely proportional to each other

83
Q

Charles Law

A

at constant pressure the volume of a fixed mass of an ideal gas is directly proportional to its absolute temperature (in kelvin)

84
Q

Gay-Lussac’s law

A

at constant volume the pressure of a fixed mass of an ideal gas is directly proportional to its absolute temperature (in kelvin).

85
Q

Combined gas law:

A

PV/T = k
P1V1/T1=P2V2/T2

86
Q

ideal gas equation

A

PV = nRT

87
Q

what unit is pressure in the ideal gas equation

A

pascals

88
Q

waht unit is volume in the ideal gas equation

A

m cubed

89
Q

waht unit is temperature in the ideal gas equation

A

kelvin

90
Q

convert cm cubed to m cubed

A

divide by 10^6

91
Q

convert dm cubed to m cubed

A

divide by 10^3

92
Q

how to convert kPa to Pa

A

multiply by 10^3

93
Q

with real gases, some of the assumptions made about ideal gases no longer apply under certain conditions

A

At very high pressure the gas particles are closer together. Under these conditions, the actual volume of the particles becomes significant.
At low temperatures, the particles move less rapidly (have lower average kinetic energy). This means that there is a greater opportunity for intermolecular forces between the particles to have an effect.

94
Q

Using the conditions of temperature and pressure at STP, the product of PV/RT for an ideal gas is always equal to

A

one.

95
Q

when is the greatest deviation from ideal behaviour seen

A

when the gas is subjected to a low temperature and a high pressure

96
Q

why is ideal behaviour deviated from at high pressure

A

spaces between particles lessen so intermolecular forces operate and particles become attracted to eachother. additionally, the non zero volume of the particles becomes significant in that the volume of a real gas at high pressure is higher than expected and PV/RT > 1.

97
Q

which gases show the most ideal behaviour

A

low molar mass and weakest intermolecular forces

98
Q

units of concentration

A

include mol dm-3, g dm-3 or parts per million (ppm).

99
Q

concentration =

A

concentration (mol dm−3)=amount of solute (mol)volume of solution (dm3)

100
Q

when would oyu use parts per million

A

in very dilute concentrations

101
Q

what is a standard solution

A

a solution with an accurately known concentration

102
Q

what is a primary standard solution

A

it has:
High purity (99.9 %).
High molar mass.
Low reactivity.
Does not change composition in contact with air.

103
Q

hy should you not use NaOH to make a primary standard solution

A

it absorbs moisture from the air

104
Q

what is a secondary standard solution

A

a solution that has been standardised against a primary standard solution.

105
Q

what is serial dilution

A

involves diluting a stock solution multiple times, usually by the same factor, which results in an exponential decrease in concentration.

106
Q

Continued dilutions will decrease the concentration by a factor of WHAT each time.

A

ten

107
Q

volumetric analysis

A

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

108
Q

describe a titration

A

A titration is a method of volumetric analysis in which the concentration of a solution can be determined. In a titration, a burette is filled with a standard solution of known concentration (the titrant). A carefully measured volume of the solution with the unknown concentration (the analyte) is placed in a conical flask below the burette (Figure 2). An indicator is used to determine the end-point of the titration. In acid–base titrations, for example, a suitable indicator is added to the solution in the conical flask and the volume of titrant required to reach the end-point of the titration is recorded. Acid–base titrations are covered in more detail in section 8.2.2.

109
Q

first trial of a titraion

A

rough titration. do not use to calculate volume

110
Q

concordant volumes are

A

0.10cm cubed within eachother

chemistry (13 decks)

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