Chemistry in the Community

Water: Exploring Solutions

Overview of Section A• Sources and Uses of Water– Direct and indirect use–Water purification–Water cycle

• Skills– Scientific method–Metric system– Lab safety–Water purification procedures

Activity: Sources and Uses of Water

Activity: Sources and Uses of Water

Questions: 1. Are all sources equally useful? Explain why or why not?2. Are any of the sources interchangeable? Explain why or

why not.3. Are any limited in availability? Explain why or why not4. Which source (or sources) would be used most

frequently? Why?5. Can we take the availability of water for granted? Why

or why not? 6. How would you group the different uses of water?

Metric System• Why metric?– Chemistry is a quantitative science,

supported by measurements and calculations

– Internationally adopted as an SI unit (SI = Le Systeme International d’Unites)

– Base units from which other units are derived

Metric SystemMetric Unit

What it is used to measure?

Example

Metric System• Metric conversions

Prefix Abbreviation Numerical Meaning Factor

kilo k 1 000 103

hecto h 100 102

deka da 10 101

deci d 0.1 10-1

centi c 0.01 10-2

milli m 0.001 10-3

micro 0.000 001 10-6

nano n 0.000 000 001 10-9

pico p 0.000 000 000 001 10-12

Metric System• Metric conversions– Quantities can be converted from one

unit to another through the use of equivalences (how they compare to each other) and a conversion factor.

Metric System• Metric conversions– Examples:• Equivalence: 1 kilogram = 1000 gram• Conversion factor:

1 kilogram or 1000 gram1000 gram 1 kilogram

• To convert 4573 g into kg multiply as follows:4573 g X 1 kg = 4.573 kg 1000 g

Metric System• Metric conversions–More Examples:

Metric equivalencesPrefix Abbreviation Numerical Meaning

kilo k 1 000

hecto h 100

deka da 10

Base Unit m, L, g 1deci d 0.1

centi c 0.01

milli m 0.001

micro 0.000 001

nano n 0.000 000 001

pico p 0.000 000 000 001

Metric conversions– Examples:• Equivalence: 1 kilogram = 1000 gram• Conversion factor:

1 kilogram or 1000 gram1000 gram 1 kilogram

• Equivalence: 100 milligram = 1 decigram• Conversion factor:

100 milligram or 1 decigram 1 decigram 100 milligram

Metric conversions– Examples from ladder worksheet

Direct and Indirect Uses of Water

• Can of orange juice takes ~120 L to produce

• A hard boiled egg takes ~450 L to produce

• What is your first reaction to these volumes?

Direct and Indirect Uses of Water• If you were to eat 2 eggs and one 1.3 L

carton of orange juice you will have expended as much water as……

…taking 10 showers…washing 10 loads of clothes…washing 25 loads of dishes…or flushing 100 times

WOW!!

Direct and Indirect Uses of Water

WHY??

Direct and Indirect Uses of Water

Direct use examples Indirect use examples

Direct and Indirect Uses of Water

• Direct Use =

• Indirect Use =

Histogram

• A frequency distribution that shows how often each different value in a set of data occurs.

• A column chart• Based on data set determine bin size

Collected data from 35 teens who have cell phonesStudent Time (min) Student Time (min)

1 10 19 54

2 24 20 33

3 243 21 156

4 22 22 35

5 34 23 86

6 67 24 46

7 32 25 88

8 34 26 97

9 64 27 201

10 7 28 24

11 54 29 46

12 43 30 86

13 68 31 78

14 90 32 5

15 222 33 88

16 122 34 87

17 45 35 53

18 96

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 More0

1

2

3

4

5

6

7

Number of Students

Time Students Spend Texting on Cell Phone

Time (minutes)

20 40 60 80 100 120 140 160 180 200 220 240 260 More0

1

2

3

4

5

6

7

8

9

Time Students Spend Texting

Number of students

Time (minutes)Range, median, mean