Ch 12 - Properties of water Flashcards

1
Q

How much of the earths land does water cover?

A

70%

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2
Q

How much does water make up of the human body?

A

70%

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3
Q

What are 4 physical properties of water

A

-is a polar molecule-freezes at 0 degrees-exissts in liquis form at 25 degrees-will boil at 100 degrees

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4
Q

Define latent heat

A

Amount of energy needed to change a substance to a different state.

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5
Q

What are the units for latent heat?

A

kJ mol-1, and Jkg-1

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6
Q

What is the symbol for latent heat?

A

L

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7
Q

Define latent heat fusion of water

A

The amount of energy required to change a fixed amount of water from a solid to a liquid state.

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8
Q

What happens in the process of latent heat fusion of water

A

The bonds in the ice are broken enabling the water molecules to move around more freely

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9
Q

What are the values for latent heat fusions?

A

6.02kJ energy is needed to change one mole of water from a solid to a liquid

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10
Q

Define latent heat of vaporisation

A

Amount of energy hat is needed to change a fixed amount of water from a liquid to a gas.

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11
Q

Does water have a high latent heat?

A

Yes

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12
Q

Why is it that water has a high latent heat

A

Strong intermolecular forces between states

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13
Q

What are the values for latent heat vaporisation?

A

40.7 mol (needed to vaporise one mole of water)

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14
Q

What is perspiration and how does it involve latent heat vaporisation?

A

Perspiration is a way of removing unwanted heat from the body, .

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15
Q

Define specific heat capacity

A

The amount of energy needed to raise one gram of substance by one degree

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16
Q

The formula for specfic heat capacity

A

Q=mct

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17
Q

What is the pattern with high specific heat capacity and energy?

A

The higher the specific heat capacity the more energy it will need to absorb to raise the temperature.

18
Q

What is waters specific heat

A

4.15

19
Q

What is ethanols specific heat

A

2.5

20
Q

Define density

A

The measure of amount of mass that is contained in a certain volume of substance

21
Q

Formula for density

A

d=m/v

22
Q

What are the units for density?

A

gcm-3 and kgm-3

23
Q

What is the official symbol for density?

A

p

24
Q

Is ice or liquid water more dense

A

Liquid water

25
Q

At what temperature is water at its densist

A

4 degrees celcius

26
Q

Does ice float on water

A

Yes

27
Q

What does the low density of ice mean?

A

It expands when frozen

28
Q

Does pure water conduct electricity

A

In the very slightest, however is described as a non-conductor

29
Q

Define self-ionisation

A

Water molecules reacting slightly with one another to produce a small amount of ions

30
Q

What bonds so water have?

A

dispersion and hydrogen

31
Q

What elements does the hydrogen bind to

A

Fluorine, nitrogen and oxygen

32
Q

Explain the strength of hydrogen bonding

A

No electrons left to shield one side as both of the hydrogens are drawn towards the oxygen, hence water can attract other molecules very closely resulting in a stronger bond.

33
Q

Do temperatures usually increase or decrease down a group?

A

increase due to having to break down larger molecules which require more energy.

34
Q

List ways the hydrogen bonding affects the properties of water

A

-High melting and boiling points-High latent heat (fusion and vaporisation)-High heat capacity-Ablitlity of water to dissolve other substances

35
Q

What is water also reffered to as in regards to solubility?

A

The universale solvent

36
Q

Are water moelcules polar or non-polar

A

POlar

37
Q

What is the rule to do with dissolving

A

like dissolves like

38
Q

Explain how water produces hydrated ions

A

Salt is placed in the water and the water surrounds the postiive and negative ions and pulls them apart

39
Q

List the behaviour of some substances in water

A

-some can remain undissolved-ionisation (polar molecules reacting with water to orm ions)-Ionic substances may dissociate-Other polar molecuels such as (suagr and ethanol) can still undergo disscation however the solution will not conduct electricty

40
Q

Do polar gases dissolve easily in water?

A

YEs e.g ammoinia gas and hcl gas

41
Q

Do non-polar gases dissolve easily in water?

A

NO

42
Q

What can have an impact on gases dissolving in wate?r

A

-Temperature: Generally an increase in temperature will decrease solubility