Ch 10 Section 5 Flashcards Preview

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Flashcards in Ch 10 Section 5 Deck (43):
1

water is the most abundant

liquid

2

oceans, rivers, and lakes cover about

75% of earth's surface

3

water is an essential component of all organisms: 70% to 90% of the mass of living things is

water

4

the chemical reactions of most life processes takes place in water, and water is frequently a

reactant or product in such reactions

5

water molecules consist of two atoms of hydrogen and one atom of

oxygen united by polar-covalent bonds

6

water molecule shape:

bent

7

the angle between the two hydrogen-oxygen bonds is about

105 degrees

8

this is close to the angle expected for ... of the oxygen-atom orbitals

sp3 hybridization

9

the molecules in solid/ liquid wate rare linked by

hydrogen bonding

10

the number of linked molecules decreases with increasing temperature because increases in kinetic energy make

hydrogen bond formation difficult

11

nevertheless, there are usually from ... to ... molecules per...

4 to 8; group in liquid water

12

if it were not for these molecular groups, water would be a

gas at room temperature

13

nonpolar molecules, such as methane, that are similar in size and mass to water molecules do not

undergo hydrogen bonding. they are gases at room temp

14

ice consists of water molecules in the

hexagonal arrangement

15

the empty spaces between molecules in this pattern account for the relatively

low density of ice

16

as ice is heated, the increased energy of the molecules causes them to

move and vibrate more vigorously

17

when the melting pt is reached, the energy of the molecules is so great that the

rigid open structure of the ice crystals breaks down, and ice turns into liquid water

18

hydrogen bonds between molecules of liquid water at 0 degrees celsius are .... and more .... than those between molecules of ice at the

fewer; disordered; same temperature

19

because the rigid open structure of ice has broken down, water molecules can

crowd closer together

20

liquid water is

denser than ice

21

as the liquid water is warmed from 0 degrees celsius, the water molecules

crowd still closer together

22

water molecules are as tightly packed as possible at

3.98 degrees celsius

23

at temperatures above 3.98 degrees celsius, the increasing kinetic energy of the water molecules causes them to

overcome molecular attractions

24

the molecules move farther apart as the temperature continues to

rise

25

as the temperature approaches the boiling point, groups of liquid water molecules absorb enough energy to

break up into separate molecules

26

because of hydrogen bonding between water molecules, a high kinetic energy is needed, causing water's boiling point to be

relatively high (100 degrees celsius) compared to other liquids that have similar molar masses

27

at room temperature, pure liquid water is

transparent, odorless, tasteless, and almost colorless

28

any observable odor or tase is caused by

impurities, such as dissolved minerals, liquids, or gases

29

water freezes and ice melts at

0 degrees celsius at a pressure of 1 atm

30

molar enthalpy of fusion of ice is

6.009 kJ/mol

31

the molar enthalpy of fusion of ice is relatively larged compared with the molar enthalpy of fusion of

other solids

32

water has the unusual property of .... in volume as it freezes, because its molecules form an..

expanding; open rigid structure

33

ice at 0 degrees celsius has a density of only about .... wile liquid water at 0 degrees celsius has a density of

.917 g/ cm3 ; .99984 g/ cm3

34

this lower density explains why ice floats in

liquid water

35

the insulating effect of floating ice is particularly important int he case of

large bodies of water

36

iv ice were more dense than liquid water, it would sink to the bottom of

lakes and ponds, where it would be less likely to melt completely

37

the water of such bodies of water in temperature climates would eventually

freeze solid, killing nearly all the living things in it

38

at 100 degrees celsius (boiling point at 1 atm) water's molar enthalpy of vaporization is

40.79 kJ/ mol

39

both the boiling pt and the molar enthalpy of vaporization of water are quite high compared with those of

nonpolar substances of comparable molecular mass, such as methane

40

the values are high because of the strong hydrogen bonding that must be overcome for

boiling to occur

41

the high molar enthalpy of vaporization makes water useful for

household steam-heating systems

42

the steam (vaporized water) stores a great deal of

energy as heat

43

when steam condenses in radiators, great quantities of

energy are released