Chemistry in the Community

The approach of the ChemCom course is to study a societal problem or issue, then introduce and develop chemical concepts that address and deal with this issue.

1A. Sources and Uses of Water

Objectives Unit 1A: Sources and Uses of Water Identify direct and indirect water uses. Learn about water purification techniques. Learn the hydrologic cycle. Identify main sources of water on Earth.

Do Now: read News articles on pgs. 4-6 These articles are the basis of the Unit 1 Reading guide chart

A.1: Items to think about What may have caused the fish kill? Is the water safe to drink? What are the various concerns of the citizens?

The story may be imaginary, but the problems are not. These challenges face humans every day.

Two water-related challenges: Can we get enough water to supply are needs? Can we get sufficiently pure water?

1. This water is obviously clear, but is it pure? 2. What is “pure” water? 3. How pure does the water need to be?

ChemQuandry Facts: page 8 It takes about 120 L of water to produce one 1.3 L can of fruit juice. It takes about 450 L of water to put one fried egg on your plate. Why does it take so much water?

ChemQuandry Facts: page 8 Handout: make a list of how water is used in juice production and egg production.

In egg production water is used: For drinking by chickens. To grow chicken feed. Grow trees to build chicken houses. Wash the eggs. Produce the carton to package the eggs.

In juice production water is used: Grow fruit trees. Wash the fruit. Process fruit into juice. Mining ore to produce the cans. Production of the can itself.

A.2: Activity: Data Table: Water use in a typical household. How much water do you think you use each day? How is water used in your daily life? Data Table: Water use in a typical household. Complete the table (similar to table on page 9)

A.3: Lab – Foul Water Students will purify a foul water sample so it could be used to wash hands. Introduce the concept of water purity and what is pure water. Techniques include: filtration, absorption, separation. Work in pairs. Distillation purification is impractical on a large scale due to cost and equipment use. Show video during lab period.

A.4 – Water Supply and Demand Is the United States in danger of running out of water? The answer is yes and no. Each day about 4 trillion gallons of rain or snow fall in the United States. Only 10% is used by humans. The rest flows in large bodies of water or evaporates into the air, and falls again. This is known as the water cycle or hydrologic cycle. (Figure) So the answer is No. However, the distribution of rain an snow in the United States does not necessarily correspond to areas of highest water use.

Water Cycle http://www.uwsp.edu/geo/faculty/ritter/images/hydrosphere/hydrocyc_small.jpg

This is related to the ChemQuandry we did with fruit juice. The average U.S. family of four ( 2 adults and 2 children) use an average of 1480 liters (390 gallons) of water daily. This volume represents direct water use, that which can be easily measured. There is also indirect water use, hidden uses of water that you never have considered. This is related to the ChemQuandry we did with fruit juice. Includes drinking water for chickens, water to grow chicken feed and water for processing the product. However, the distribution of rain flow is not equal in all parts of the country. Areas of high use may not get enough rain or snow. See figure. So the answer is YES for certain parts of the country.

Direct vs. Indirect Usage of Water Direct water use – Water that can be directly measured Indirect water use – Water that can not be directly measured Revisit Chem Quandry on page 8.

A.5: Homework: Answer questions 1-3 on page 17

A.6 Where is the world’s water? Most of the Earth’s total water is from the ocean (about 97%) The remaining 3% is fresh water and it is stored mostly in glaciers Examples: next slide

Water can be found in three different physical states Gaseous state: water vapor in the air (humidity) Liquid state: lakes, oceans, rivers and rain Solid state: ice and glaciers

City Water Comes from underground pipes Water comes from a reservoir or water tower Water has been treated and purified If the water originated from a river it is called SURFACE WATER

Rural Water May have its own water supply in the form of a well Aquifer – (a water-bearing layer of rock, sand or gravel) Water is then usually held in a tank before being brought into the home. If the water has originated from a well you are using GROUND WATER

A.7: Water –Use Analysis Complete the water-use analysis chart and answer questions 1-6. Use table 1.1 on page 20 Use worksheet A.2 to help complete the analysis.

A.8: Water –Types Potable Water – is pure enough for use in drinking and cooking. Grey Water – is left over from home use (such as showers, sinks, laundry and dishwashers. Can be used for other purposes such as watering the lawn. Black Water – has contacted toilet waste and must be treated before reuse. 29

A.8: Water –Types List three water uses that you do without? Identify one activity that you could not For which tasks could you reduce your water use 30 30

Homework: Unit 1 Section A Supplement Answer questions 1 – 7. Due: Period 6: Friday, September 27th Period 1: Monday, September 30th