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Year 1 - University > Core inorganic and physical chemistry for forensic science > Flashcards

Core inorganic and physical chemistry for forensic science Flashcards

1
Q

What does the state in which a substance exist depend upon?

A

The competition or balance between intermolecular forces and thermal energy

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2
Q

What is the equation for pressure?

A

Force/area

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3
Q

What is mechanical equilibrium?

A

Equality of pressure

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4
Q

Define diathermic

A

Thermally conducting

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5
Q

Define adiabatic

A

Thermally insulating

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6
Q

Define thermal equilibrium

A

No change of state occurs when two object are in contact through a diathermic boundary

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7
Q

Zeroth Law of Thermodynamics

A

If A is in thermal equilibrium with B, and A is in thermal equilibrium with C, then C is also in thermal equilibrium with B

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8
Q

Charles’ Law

A

At a constant pressure, the volume of a fixed mass of gas is proportional to its pressure

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9
Q

Boyle’s Law

A

Provided temperature is kept constant, the volume of a fixed mass of gas is inversely proportional to its pressure

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10
Q

Law of combining volumes (Gay-Lussac)

A

At any given p and T, the volumes of gases that react with one another are in the ratios of small whole numbers

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11
Q

Avogadro’s hypothesis

A

equal volumes of gases at the same p and T contain an equal number of molecules

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12
Q

Avogadro’s Law

A

volume of a gas maintained at a constant pressure and temperature is directly proportional to the number of moles in the gas

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13
Q

what assumptions were made about the ideal gas law

A

there are no intermolecular forces in the gas, and gas molecules have no volume

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14
Q

what is the critical point

A

a set of conditions under which a liquid and its vapour become identical

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15
Q

system

A

part of the world in which we have special interest

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16
Q

surroundings

A

region outside the system where we make our measurements

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17
Q

what is work defined as

A

motion over some distance against an opposing force

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18
Q

what is the equation for work when pressure is constant

A

-P x change in V

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19
Q

Name the 3 ways the energy of a system may be changed other than work itself

A

heat (energy change results from a temperature difference between system and surroundings), exothermic process, endothermic process

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20
Q

what is the difference between endothermic and exothermic

A

exothermic is when energy is transferred as heat to the surroundings, endothermic is when energy is acquired from its environment as heat

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21
Q

define internal energy (U)

A

total energy of a system

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22
Q

define the first law of thermodynamics

A

the change in energy of a system is equal to the sum of the work done on the system and heat put into the system

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23
Q

what is the equation for the change in U

A

q + w

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24
Q

define calorimerty

A

study of heat transfer during physical and chemical processes

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25
Q

define calorimeter

A

device for measuring energy transferred as heat

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26
Q

define adiabatic process

A

transfer of energy in the form of work only

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27
Q

define thermochemistry

A

the study of energy transferred as heat during the course of chemical reactions

28
Q

what is the enthalpy change for an exothermic reaction

A

< 0, negative

29
Q

define standard enthalpy change

A

the change in enthalpy for a process in which the initial and final substances are in their standard states

30
Q

define standard enthalpy of transition

A

the standard enthalpy change that accompanies a change of physical state

31
Q

define the standard enthalpy of sublimation

A

a change in enthalpy independent of the path between two states

32
Q

define Hess’s law

A

the overall enthalpy change of a reaction is independent regardless of the route taken

33
Q

define standard enthalpy of formation

A

the enthalpy change to form a compound from its elements under standard conditions with all products and reactants in their standard states

34
Q

define mean bond enthalpy

A

the average enthalpy change associated with the breaking of a specific bond

35
Q

define Kirchoff’s Law

A

standard reaction enthalpies at different temperatures can be calculated from the heat capacities at constant pressure

36
Q

define spontaneous reactions

A

those that, once started, will continue without any outside intervention

37
Q

define the second law of thermodynamics

A

the state of entropy of the entire universe, as an isolated system, will always increase over time

38
Q

Define the third law of thermodynamics

A

the entropy of a pure crystalline substance at absolute zero is zero

39
Q

If G<0…

A

the reaction is spontaneous in the forward direction

40
Q

If G=0…

A

the reaction is at equilibrium

41
Q

If G>0…

A

the reaction is non-spontaneous in the forward direction but the reverse direction is spontaneous

42
Q

name the 4 factors which affect reaction states

A

physical state of reactions, reactant concentrations, reaction temperature, the presence of a catalyst

43
Q

define chemical rate

A

the change in the concentration of reactants or products per unit of time

44
Q

define reaction rate

A

either the rate of the disappearance of A or the rate of the appearance of B

45
Q

equation for rate

A

concentration/time

46
Q

what are the four ‘rules’ for collision theory

A

particles must collide before reaction, not all collisions lead to reactions, reactions must have an activation energy, for the reaction to occur the molecules must collide at a specific orientation

47
Q

define steric hinderance

A

when molecules are large so it is harder for them to collide at the correct orientation

48
Q

what are the 4 factors rate of reaction can be increased by

A

increasing surface area, increasing concentration, increasing temperature, using a catalyst

49
Q

define first order

A

when the rate doubles, the concentration doubles

50
Q

define second order

A

when the concentration doubles, the rate quadruples. It is the square of what happens to the concentration

51
Q

define half-life

A

the time required for the concentration of a reactant to react half of its initial value

52
Q

define heterolysis

A

one of the atoms gains both electrons and becomes negatively charged

53
Q

define homolysis

A

each atom keeps one of the bonding pairs of electrons, forming free radicals

54
Q

define rate determining step

A

slowest step which limits the overall reaction rate

55
Q

define the effective nuclear charge (Zeff)

A

the amount of positive charge experienced by an electron from the nucleus

56
Q

what is the equation for Zeff

A

Z-S, where Z is the nuclear charge and S is the shielding constant

57
Q

describe the trends of effective nuclear charge

A

increases across a period as protons are added to the nucleus, and increases down a group as the increase in protons is offset by the increased number of shielding electrons

58
Q

describe the trends in orbital energies

A

increase down a group as they increase with the value of n, and decrease across a period because n remains unchanged and Zeff dominates

59
Q

describe the trends in atomic size

A

decreases across a period due to increasing Zeff, and increases down a group as orbitals with a higher n have larger radii

60
Q

define ionisation energy

A

the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

61
Q

describe the trends in ionisation energy

A

increases across a period due to increasing Zeff, and decreases down a group as there is lower nuclear attraction

62
Q

define electron affinity

A

the energy required to add an electron to each atom in one mole of gaseous atoms to form one mole of 1- ions

63
Q

describe the trends in electronegativity

A

decreases down a group as atomic radius and shielding are increasing, and increases across a period due to an increase in nuclear charge and a decrease in atomic radius

64
Q

define electronegativity

A

measure of the tendency of an atom to attract a bonding pair of electrons

65
Q

define redox reaction

A

process of electrons being transferred between species, both oxidation and reduction occur

66
Q

define reducing agent

A

species which donates electrons, the species itself is oxidised

67
Q
A

Year 1 - University (3 decks)

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