Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A-LEVEL CHEMISTRY > THERMODYNAMICS > Flashcards

THERMODYNAMICS Flashcards

You may prefer our related Brainscape-certified flashcards:
Chemistry 101 flashcards AP® Chemistry flashcards Periodic Table flashcards Organic Chemistry 101 flashcards
1
Q

What is thermodynamics? (1)

A

the study of how heat and temperature relate to energy and work.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the born Haber cycle? (1)

A

a way to analyse and break down the enthalpy changes associated with the formation of an ionic compounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is Hess’s law based on? (1)

A

based on the idea that energy is conserved and cannot be destroyed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what does Hess’s law state? (1)

A

the enthalpy change of a chemical reaction is independent of the path taken.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the equation to work out the enthalpy change of formation? (1)

A

enthalpy change of reaction = (sum of) enthalpy change of formation (products) - (sum of) enthalpy change of formation (reactants)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the equation to work out the enthalpy change of combustion? (1)

A

enthalpy change of reaction = (sum of) enthalpy change of combustion (reactants) - (sum of) enthalpy change of combustion (products)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the standard enthalpy change of formation? (1)

A

the standard enthalpy change of formation is the enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions, all reactants and products in their standard states.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the standard molar enthalpy change of combustion? (1)

A

the standard molar enthalpy change of combustion is the enthalpy change when one mole of substance is completely burnt in oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the standard enthalpy of atomisation? (1)

A

the standard enthalpy of atomisation is the enthalpy change which accompanies the formation of one mole of gaseous atoms from the element in its standard state under standard conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the first ionisation energy? (1)

A

the first ionisation energy is the standard enthalpy change when one mole of gaseous atoms is converted into a mole of gaseous ions each with a single positive charge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the first electron affinity? (1)

A

the first electron affinity is the standard enthalpy change when a mole of gaseous atoms is converted to a mole of gaseous ions, each with a single negative charge. (exothermic reaction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the second electron affinity? (1)

A

the second electron affinity is the enthalpy change when a mole of electrons is added to a mole of gaseous ions each with a single negative charge to form ions each with two negative charges. (endothermic reaction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the lattice of formation? (1)

A

the lattice of formation is the standard enthalpy change when one mole of solid ionic compounds is formed from its gaseous ions. is always negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the lattice enthalpy of dissociation? (1)

A

the lattice enthalpy of dissociation is the standard enthalpy change when one mole of solid ionic compounds dissociated into its gaseous ions. is always positive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the enthalpy of hydration? (1)

A

the enthalpy of hydration is the standard enthalpy change when 1 mole of gaseous ions are converted to aqueous ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the enthalpy of solution? (1)

A

the enthalpy of solution is the standard enthalpy change when one mole of solute dissolves completely in sufficient solvent to form a solution in which the molecules or ions are far enough apart not to interact with each other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the mean bond enthalpy? (1)

A

the mean bond enthalpy is the enthalpy change when one mole of gaseous molecules each breaks a covalent bond to form two free radicals averaged over a range of compounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the first step of using a born Haber cycle? (1)

A

start with elements in their standard states

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the second step of using a born Haber cycle? (1)

A

add in atomisation of element 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the third step of using a born Haber cycle? (1)

A

add in atomisation of element 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what is the fourth step of using a born Haber cycle? (1)

A

add in ionisation of metal element

22
Q

what is the fifth step of using a born Haber cycle? (1)

A

add in electron affinity of non-metal element

23
Q

what is the sixth step of using a born Haber cycle? (1)

A

add in enthalpy of formation of element 1

24
Q

what is the seventh step of using a born Haber cycle? (1)

A

the final unknown quantity is the lattice formation enthalpy of the ionic compound.

25
Q

what is the bond dissociation enthalpy? (1)

A

the bond dissociation enthalpy is the energy needed to break one mole of gaseous bonds to give separated atoms. is an endothermic process so is a positive value.

26
Q

what factors effect the lattice enthalpy? (2)

A

-the charge on the ion
-the size of the radius

27
Q

what effect does the charge of an ion have on the lattice enthalpy? (1)

A

the charge on the ions increases, the lattice energy increases, as the size of the ions decrease the lattice energy decreases

28
Q

what effect does the size of the radius have on lattice enthalpy? (1)

A

the smaller the ion, the greater the charge density and therefore the force of attraction is greater between ions.

29
Q

why is the second electron affinity endothermic? (1)

A

because they to overcome electron on electron repulsion - electrostatics tell us that like charges repel, the electron is negatively charged and so is the negative ion.

30
Q

what do ionic solvents dissolve well in? (1)

A

ionic solvents dissolve well in polar solvents.

31
Q

what is needed to dissolve an ionic solvent? (1)

A

in order to dissolve an ionic compound the lattice must be broken up, this requires an input of energy (lattice enthalpy)

32
Q

why do some values of enthalpy formation differ? (1)

A

in some ionic compounds there is a large discrepancy between the two values for lattice formation because the bonding in question has covalent character.

33
Q

what does the distortion present in some compounds do to the enthalpy change of formation value? (1)

A

this distortion means there are more electrons than expected concentrated between the metal and non-metal nuclei represents a degree of electron sharing or covalent accounts for the lattice enthalpy of discrepancy.

34
Q

what factors increase polarisation? (2)

A
  • positive ion (small size, high charge)
  • negative ion (large size, high charge)
35
Q

how do you work out the enthalpy change of solution? (3)

A
  • add the enthalpy change for the lattice dissociation of the compound
  • add the enthalpy change for the solution of the metal atom
  • add the enthalpy change for the solution of the non-metal atom
36
Q

what does the perfect ionic model assume? (2)

A

-all bonds are ionic
-all ions are perfect spheres/point charges

37
Q

what effect does covalent character have on the enthalpy change of solution? (2)

A

-if the calculated value is close to that seen in the born Haber cycle it has very little covalent character
-as the amount of covalent character increases the magnitude of the lattice enthalpy calculated from the born Haber cycle becomes greater compared to the perfect ionic model.

38
Q

what occurs in enthalpy change of hydration? (1)

A

when a substance dissolves electrostatic attractions are formed between the polar water molecules and the ion in question.

39
Q

what factors effect the enthalpy change of hydration? (2)

A

-the strength of the attraction between the ion and water, the smaller the ions, the greater the attraction therefore the greater the hydration enthalpy.

40
Q

what is the general trend in hydration enthalpies? (1)

A

hydration enthalpies decrease going down a group.

41
Q

What are the terms feasible and spontaneous used to describe? (1)

A

chemists use the terms feasible or spontaneous to describe reactions that take place on their accord.

42
Q

what in the entropy of a system? (1)

A

the randomness of a system, expressed mathematically

43
Q

how does temperature effect the entropy of a system? (1)

A

entropies increase with temperature, largely because at higher temperatures particles spread out and randomness increases.

44
Q

how can the entropy change of a reaction be calculated? (1)

A

can be calculated by adding all the entropies of the products and subtracting the sum of the entropies of the reactants.

45
Q

what factors govern the feasibility of a reaction? (2)

A

two factors govern the feasibility of a chemical reaction;
-the entropy and enthalpy change.

46
Q

what must the Gibbs free energy change be for it to be a feasible reaction? (1)

A

the result must be negative for the reaction be feasible and will be positive if it is not feasible.

47
Q

what does Gibbs free energy change depend on? (1)

A

depends on temperature meaning that some reactions may be feasible at one temperature but not at another.

48
Q

what is entropy? (1)

A

matter and energy tend to disperse and become more disordered, the degree of disorder is measured by its entropy.

49
Q

when is a system most stable? (1)

A

a system becomes more stable when its energy is spread out in a more disordered state. (most stable in a gas - high entropy)

50
Q
A

A-LEVEL CHEMISTRY (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions