Chapter 12-Properties of Water Flashcards Preview

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Flashcards in Chapter 12-Properties of Water Deck (42):
1

How much of the earths land does water cover?

70%

2

How much does water make up of the human body?

70%

3

What are 4 physical properties of water

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

4

Define latent heat

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

5

What are the units for latent heat?

kJ mol-1, and Jkg-1

6

What is the symbol for latent heat?

L

7

Define latent heat fusion of water

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

8

What happens in the process of latent heat fusion of water

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

9

What are the values for latent heat fusions?

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

10

Define latent heat of vaporisation

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

11

Does water have a high latent heat?

Yes

12

Why is it that water has a high latent heat

Strong intermolecular forces between states

13

What are the values for latent heat vaporisation?

40.7 mol (needed to vaporise one mole of water)

14

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

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

15

Define specific heat capacity

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

16

The formula for specfic heat capacity

Q=mct

17

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

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

18

What is waters specific heat

4.15

19

What is ethanols specific heat

2.5

20

Define density

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

21

Formula for density

d=m/v

22

What are the units for density?

gcm-3 and kgm-3

23

What is the official symbol for denisty?

p

24

Is ice or liquid water more dense

Liquid water

25

At what temperature is water at its densist

4 degrees celcius

26

Does ice float on water

Yes

27

What does the low density of ice mean?

It expands when frozen

28

Does pure water conduct electricity

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

29

Define self-ionisation

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

30

What bonds so water have?

dispersion and hydrogen

31

What elements does the hydrogen bind to

Fluorine, nitrogen and oxygen

32

Explain the strength of hydrogen bonding

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

Do temperatures usually increase or decrease down a group?

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

34

List ways the hydrogen bonding affects the properties of water

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

35

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

The universale solvent

36

Are water moelcules polar or non-polar

POlar

37

What is the rule to do with dissolving

like dissolves like

38

Explain how water produces hydrated ions

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

39

List the behaviour of some substances in water

-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

Do polar gases dissolve easily in water?

YEs e.g ammoinia gas and hcl gas

41

Do non-polar gases dissolve easily in water?

NO

42

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

-Temperature: Generally an increase in temperature will decrease solubility