What is pH?

1. What is pH?

2. Acids and Bases 2 • Some of our favorite foods make our tongue curl up because they are SOUR.

3. Bitter! 3 • Some foods have a “bite” of their own because they’re somewhat bitter. • WHY?

4. The scientific reason for this: 4 • These foods are either acidic or basic. • Liquids can be acidic or basic too

5. Acids and Bases 5 • Chemicals may be classifyied as acids or bases. • Things that are neither acids nor bases are neutral. • pH measures how acidic or basic a solution is.

6. Acids 6 • Often taste sour * • Strong acids can burn skin & eyes • Strong acids can dissolve metals • Examples: • Stomach acid (very strong) • Lemon juice, tomatoes, vinegar • Car battery acid (dangerous!) *Never test an unknown acid by tasting it!

7. Bases 7 • Can taste bitter, sweetish, or salty * • Often feel slippery or “soapy” * • Strong bases can burn skin & eyes • Bases are often used for cleaning • Examples: • Milk • Baking soda, soap, bleach • Borax (like what we added to make goop) • Sea water (slightly) • Drain cleaner (dangerous!) *Never test an unknown base by touching or tasting it!

8. 8 No I am Not: • Some substances are not really an acid or a base: For example, pure water

9. pH 9 • pH stands for “potential Hydrogen” • Acids form hydrogen ions H+ in water. • Bases form hydroxide ions (OH)- in water

10. It’s simple! We measure pH by using special strips of paper called pH paper How Do We Measure pH? 10

11. How Does It Work? 11 • The paper is treated with chemicals that change color to show the pH. • When the paper touches the substance being tested, it turns a specific color to tell if the substance is an acid or a base.

12. Acid 12 • If the pH is less than 7, it is an acid 0--------------7---------------14 Acid Neutral Base

13. Base 13 • If the pH is greater than 7, it is a base 0--------------7---------------14 Acid Neutral Base

14. Neutral 14 • A pH of 7 is called neutral—neither acid nor base. 0------------7------------14 Acid Neutral Base

15. The pH Scale 15 • pH scale ranges from 0 (red) -14 (bluepurple) • pH 7 is neutral (yellow); neither acid nor base • Pure water is pH 7 • The closer to the ends of the scale, the stronger the solution is

16. 16 The pH Scale

17. How does pH affect our environment? • It can affect our soil • It can affect out water • From a fish tank, to a swimming pool, to our oceans! • It has a huge affect on our oceans!!!

18. pH and our environment:

19. pH in our soil • Acidic soil (pH is low number) is usually where oak trees grow. • when oak trees leaves fall to the ground, the soil turns acidic from the leaves – and grass can’t grow there (ever notice that green grass doesn’t grow under an oak tree?) • Farmers/vineyards need to keep track and check the pH of their soil. • Green grass needs a more neutral pH soil

20. pH in our water • Hot tubs and swimming pools need to have their pH levels checked • Fish need a specific pH. Goldfish can’t live if there is too much ammonia ( too “basic”) • Ocean life is sensitive; ocean life can’t live in an environment that has: • too high of pH, greater than 7 (too basic) or • too low of a pH, less than 7 (acidic)

21. But what about our water on Earth? • The acidity of Earth’s water is changing due to pollution: too much pollution creates acid rain and it is changing the acidity of our oceans.

22. Acid Rain • Occurs all over the world – see map • Happens because the pollution is absorbed by the clouds, the clouds absorb the carbon from the pollution, which chemically creates an acid - and neutral rain changes into acidic rain. Acidic rain changes the water cycle of many countries • Over time, acid rain can destroy the metal on cars, buildings, and it can runoff into streams, change the soil, and kill forests

23. pH in our oceans • We have too much pollution in our atmosphere. • Our oceans absorb the carbon from the pollution, which chemically creates acid, and then this changes the acidity of our oceans. • The acidic ocean then dissolves the coral reefs which are home to many varieties of sea life. Once their gone, their gone.

24. What can be done? We need to pay attention to our environment. Go green – recycle, change the way you buy things, change the way you travel, change the way you throw away garbage – a little goes a long way.