6th graders - Complete answers on your study guides before tomorrow's Water Unit test (Friday.)

Graphic courtesy of the Clean Freak webpage at http://www.cleanfreak.com/blog/chemistry/

14. Municipal water plants send water out to homes and businesses.  How do they:

1. Test for contaminants? (name at least 3 tests they can use. See p. C-59):

ans:  turbidity, pH, nitrates, copper, odor, iron,

2. Treat for biological contaminants? (name at least 3 methods. See p. C-69-71):

***ans: chlorination!  To a lesser extent, coagulation and filtration.   

  15. What is chlorination used for?  ans: chlorination Kills bacteria

16. If you use Universal Indicator Solution, what types of chemicals react with UIS to turn the solution to the color:

1. Red/Orange means the chemical is a(n)  ans: acid ______:
2. Yellow-Green means the chemical is a(n) ans: neutral
3. Blue or violet means the chemical is a(n) ans: base

17.How is water pollution different from water contamination?

ans: water pollution is both harmful & man-made, while water contamination may not be one or the other.

18. Match the following pollutant with its correct classification:

1.    b._Wild bird waste                                a. Non-point source pollution

2.    _c._Paint Factory chemicals                 b. Natural Biological contamination

3.    _a._Diesel (truck) fuel                          c. Point source pollution                                                                                                                                                                      

19.     What is an acid? 

Ans: An acid is a corrosive chemical that has a pH less than 7 when mixed with water and a pH indicator.

20.    List three properties of acids:

a.    pH less than 7 in presence of indicator

b.    sour in taste

c.    sticky to touch  OR

d.    react strongly with metals and flesh

21.    What is a base? 

Ans: corrosive substance that shows a pH of greater than 7. Bases are bitter in taste, and slippery to touch. They react strongly with oils, grease, fats.

22.    List three properties of bases:

a.    pH of greater than 7.

b.    Bases are bitter in taste

c.    slippery to touch – OR-

d.    react strongly with oils, grease, fats.

23.   

Acid                       Base ·         Corrosive  ·         Not neutral

Draw a Venn diagram showing differences and similarities between acids and bases.

			·                       pH of greater than 7. ·            Bases are bitter in taste ·            slippery to touch   ·           react strongly with oil, fat,      grease.
	·      pH less than 7 w/ indicator ·      sour in taste ·      sticky to touch  ·      react strongly w/metals & flesh

 

24    What is neutralization? What happens to acids or bases when they are combined?

Ans: when an acid is added to a base until evenly balanced to produce a neutral (pH = 7 ) solution. Acids and bases lose their acid or base nature.

25.     What are two properties of neutral substances?   They are neither acid nor base and they have a pH of about _7_.

26.    What is the pH scale? Define it, draw it, and be sure to explain what the numbers mean in terms of the nature of the chemicals in each part of the pH scale. 

 Ans: The pH scale ranges from 0 to 14, with neutral at 7, strongest acids near 0-3 and strongest bases near 12-14.