Oceans Flashcards

1
Q

What are the two types of solvent?

A

Polar and non Polar

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2
Q

Why do ionic substances only dissolve in polar solvents?

A

The ion-dipole bonds formed are stronger than the electrostatic forces between the ions

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3
Q

Why don’t ionic substances dissolve in non-polar solvents?

A

Non polar molecules don’t interact strongly enough with the ions

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4
Q

Why do covalent substances dissolve in non-polar solvents?

A

Intermolecular bonds between covalent molecules are weak and can be broken by non polar solvents

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5
Q

Why don’t covalent molecules tend to dissolve in polar solvents?

A

Hydrogen bonds between water molecules are stronger than bonds between covalent molecules and the water.

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6
Q

How do ionic solids dissolve in water?

A

1) partially positive charge on H attracted to negative ions
2) partially negative charge on O attracted to positive ions
3) Ions separate from ionic lattice and becomes surrounded by water molecules

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7
Q

What is Hydration?

A

When a molecule becomes surrounded by water molecules

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8
Q

What is an ion called when it is surrounded by water molecules?

A

Hydrated ion

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9
Q

What is hydration called when the solvent isn’t water?

A

Solvation

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10
Q

What is the definition of standard lattice enthalpy?

A

the enthalpy change when `1 mole of an ionic lattice is formed from its gaseous ions under standard conditions

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11
Q

What is a giant ionic lattice?

A

Positive and negative ions held together by electrostatic attractions in a lattice (formed by ionic compounds)

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12
Q

What charge is lattice enthalpy?

A

Always negative because bonds and broken and energy is released

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13
Q

What makes standard lattice enthalpy more negative?

A

It is a measure of bond strength so the stronger the bonding the more negative it is

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14
Q

What is the definition of enthalpy change of hydration?

A

The enthalpy change when 1 mole of aqueous ions is formed from gaseous ions.

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15
Q

Is enthalpy change of hydration endothermic or exothermic?

A

exothermic

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16
Q

What is the definition of enthalpy change of solution?

A

Enthalpy change 1 mole of an ionic substance dissolves in enough solvent to form an infinitely dilute solution

17
Q

What is the overall effect on enthalpy when something dissolves called?

A

enthalpy change of solution

18
Q

How do you measure enthalpy change of solution using an experiment?

A

Put reactants in polystyrene and measure temp change

19
Q

What equation do you use to calculate enthalpy change?

A

q=mc x change in temp

20
Q

What is charge density?

A

charge/radius

21
Q

How is lattice enthalpy affected by charge density?

A

Ions with higher charge density are better at attracting each other in ionic lattices - so it has a more exothermic lattice enthalpy because the ionic bonds are stronger

22
Q

How does charge density affect enthalpy of hydration?

A

Ions with higher charge molecules are better at attracting water molecules than those with lower charge densities - so it would have a more exothermic enthalpy of hydration

23
Q

What is solubility?

A

The maximum amount of solid which will dissolve in a certain solvent

24
Q

Equation for moles using mass

A

moles = mass/mr

25
Q

What is Ksp

A

solubility product

26
Q

What is entropy?

A

Number of ways that particles can be arranged and the number of ways that the energy can be shared between the particles.

27
Q

Does increased disorder increase or decrease energetic stability of a substance?

A

Increase

28
Q

Put the states in order of increasing enthalpy

A

solid, liquid, gas

29
Q

Why do gases have the highest disorder?

A

most random arrangement of particles

30
Q

What is energy measured in?

A

quanta - packages of energy

31
Q

How does energy affect entropy?

A

Increased energy quanta means more ways particles can be arranged and the greater entropy

32
Q

How does the moles affect entropy?

A

More moles means more particles so more ways the particles can be arranged

33
Q

What is the equation for total entropy change?

A

ΔtotS = ΔsysS + ΔsurrS

34
Q

What is the equation for entropy of the system?

A

ΔsysS = Sproducts - S reactants

35
Q

What is the equation for entropy of the surroundings?

A

ΔsurrS = -ΔH/T
ΔH in Jmol-1
T in K

36
Q

What does the total entropy change need to be for reactions to be feasible?

A

Positive or zero

37
Q

If the ΔsysS is negative what should ΔsurrS be to make the reaction feasible?

A

positive and at least as large as ΔsysS

38
Q

What factors affect entropy?

A
  • moles
  • physical states
  • temperature