Properties of Water

Practice Quiz

1. What two elements make up water?

Hydrogen (H) & Oxygen (O)

H2O2. Write the chemical formula for water.

3. Is water an element, compound, or mixture?

Compound

4. Define the term compound.

A substance with two or more elements chemically combined in definite proportions.

A covalent bond

5. What kind of chemical bond exists between a hydrogen and oxygen atom in a water molecule?

6. Draw a model of a water molecule.

7. Draw partial (+) and partial (-) charges on the water molecule you drew above.

δ +This symbol also means partial →

(+)(+)

(-) (-)The parentheses mean ‘partial.’

8. Which of the following molecules are polar?

(+)(+)

(-)(-)

(+)(-)

(-)

(-)

(-)

(-)

(+)

(+)(+) (+)

water carbon dioxide

methaneHydrogen chloride

(-)(+)

(+)

(+)

(-)

(-)

formaldehyde

(-)

(+)(+) (+)

ammonia

9. Draw two water molecules and a hydrogen bond.

10. How many hydrogen bonds can a water molecule form with other water molecules?

2

(+)

(-)Hydrogen bond

The use of dashed lines show that hydrogen bonds

are relatively weak.

Four

3

1

4

11. What term describes the attraction between molecules of the same substance?

Cohesion

12. Without a hydrogen bond, when molecule A moves to the right, will it be able to drag molecule B along with it?

AB

No

13. With a hydrogen bond between them, will molecule A be able to drag molecule B along with it?

AB

Yes

14. What are some examples of water cohesion? Surface tension

Drops on a penny Insect trapped in water

A proboscis keeps this bee at a safe

distance

15. What are some examples where surface tension breaks down?

“Scaring” pepper Bread clip motor boat

16. What term describes the attraction between molecules of different substances?

Adhesion

(+)(+)(+)(+)(+)

(-)

glassWater drop on glass slide

17. What will happen when a charged rod or balloon is brought up close to a stream of water?

The water will be attracted toward the rod

18. What are some examples of water adhesion?

A meniscus that water forms in a

glass tube.

Capillary action

Scotchgard ® carpet

19. What are some examples of anti-adhesion?

Wax-layer on leaves

Water on wax paper

Duck feathers repel water

New: Researchers have made an omniphobic material that repels both water and oil.

Nature has never made this type of material.

20. What is the term which describes the amount of heat energy needed to increase a substance’s temperature?

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.00

0.54

0.42

0.21 0.20 0.190.12 0.09

0.03 0.02

Heat Capacity of Various Materials [cal/(g·°C)]

Hea

t Cap

acit

y [c

al/(

g·°C

)] Heat Capacity

21. Which substance in the chart is able to absorb the most heat for a given change in temperature?

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.00

0.54

0.42

0.21 0.20 0.190.12 0.09

0.03 0.02

Heat Capacity of Various Materials [cal/(g·°C)]

Hea

t Cap

acit

y [c

al/(

g·°C

)] Water

22. Which substance in the chart is able to absorb the least amount of heat for a given change in temperature?

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.00

0.54

0.42

0.21 0.20 0.190.12 0.09

0.03 0.02

Heat Capacity of Various Materials [cal/(g·°C)]

Hea

t Cap

acit

y [c

al/(

g·°C

)] Air

23. What example in the Properties of Water lab demonstrated a low heat capacity for air and a high heat capacity for water?

Air-filled balloon Water-filled balloon

24. What is a mixture?A substance made up of elements or compounds that are combined but not chemically bonded together.

25. What are some examples of mixtures?

watersugarcorn syrupCO2

caramelcaffeinecitric acid

BeefOnionTomatoLettuceCheeseKetchupMustardbread

copperzinc

26. What are two kinds of mixtures made with water?

Solutions and suspensions

27. Compare solvent, solute, and solution.

Sugar water

solution

water

solventwhat does the

dissolving

Sugar cubes

solutewhat is being

dissolved

28. Define a solution?A mixture in which the molecules of the mixed substances are evenly spread out.

29. Which substance(s) below dissolve in water?

salt

polar

oil

Non polarNon polar

paraffin waxMagnesium sulfatepolar

iodine

Non polar

30. What is a suspension?

A mixture from which some of the nondissolved particles settle out slowly upon standing.

31. What some examples of suspensions?

Chocolate milk

Paint Blood

33. What does the pH scale indicate?It indicates the concentration of hydrogen ions (H+) in a solution.

32. When water breaks apart, what kind of ions are formed?

Hydrogen (H+) ions and hydroxide (OH-) ions

+

(-)

( )

34. What is the range of the pH scale?

0 to 14

35. What is the pH of a substance that has an equal number of H+ and OH- ions?

7

36. Substances with a pH below 7 are ________ while those above 7 are _________?

Acids Bases

37. Acids have more ____ions than _____ ions?

38. The _______the pH, the greater the acidity.lower

H+

OH-

39. _______ have more OH- ions than H+ ions?Bases

Oven cleanerLemon juice

Human bloodSoap

Oven cleaner

Lemon juice

Pure waterHuman blood

Soap

40. Place the 5 substances listed below on the scale to the right.

Pure waterClick for answer

41. The pH in most cells in the human body must stay between _______ and______ ?

42. __________ are weak acids or bases that can react with strong acids or bases to stop sharp, sudden changes in pH.

Buffers

6.5 7.5

43. Buffers play an important role in the process of ______________, where living things are able to maintain a stable, internal environment.

homeostasis