LIVING THINGS Properties of Water

And Acids/Bases

HEADINGSVOCAB

IMPORTANT INFO

Living Things Use & Need Energy a.) Energy comes from food, used to maintain body

b.) AUTOTROPH: produce own food

c.) HETEROTROPH: must consume food

d.) DECOMPOSER: breaks down dead material for food

Living Things Respond to their Surrounding

a.) Reaction to a stimulus

b.) Action causes a reaction

c.) Reaction is called a response

d.) Involves one individual

Question: Describe the properties of water that make it important to living things.

Water is polar ■it has an uneven

distribution of electrons between the hydrogen and oxygen atoms

■One side is positive, the other is negative

Water Properties:

A. Water is Cohesive:

▪attraction B/T same molecules

▪causes molecules to draw inward at surface

▪Ex: Some insects & spiders can “walk” on the surface of H2O

B. Water is Adhesive

▪Adhesion in water is when the water is 'sticky' or attracted to other surface

▪Attraction between different mol.

▪Causes H20 to bend at surface

▪Ex: Capillary action-pulls column of water up to the top of a plant

▪Water is called the “Universal Solvent”: dissolves many other substances due to polarity

▪Differences in charges pulls/pushes substances apart

▪ Water exhibits evaporative cooling: removes heat when it evaporates from a surface

▪Ex: sweating cools skin

▪ Water expands during freezing: expands into crystal formation releasing heat

▪Ex: rocks broken up by ice creating soil; ice layer protects fruit from freezing

Acids, Bases and the pH scale

a.The pH scale measures the concentration of H+ ions

•How acidic something is)

b. Ranges from 0-14

c. At 7: H+ ions and OH- ions are equal so it is neutral

d. ACIDS: release H+ when mixed with water

•0-7: acidic, has more H+ ions

• Sour, corrosive

• Ex: HCl, H2SO4

• Always have H+ at front of formula

e. BASES: release OH- when mixed with water

• 7-14: basic, has more OH- ions

• Bitter, slippery, usually in cleaners

• Ex. NaOH, CaOH

• Always have OH- at end of formula

What is a buffer?▪ Buffers are weak acids/bases that react with strong acids/bases

▪prevent sharp changes in pH

▪Helps to neutralize

▪Helps control pH in blood, digestive tract, etc. = maintain homeostasis (internal balance)

Quiz : The following are all examples of the characteristics of life. Identify each one.

A. Adapt D. genetic code G. Respond to stimulus

B. Made of cells E. Grow and develop H. Homeostasis

C. Reproduce F. Use/need energy

1. You eat a hamburger for lunch.

2. A baby gains 3 pounds in one week and begins to recognize voices.

3. A polar bear has white fur to blend in with the snow.

4. Your start to cry whenever you get a shot at the doctor’s office.

5. You begin to shiver because it is cold outside.

6. Red and white particles make up part of your blood.

7. A chick breaks out of an egg.

8. Your saliva measures 7 on the pH scale, it is a(n) ___ solution?

a. acidic b. basic c. neutral

9. The ___ property of water helps in the formation of soil.

a. capillary action b. expansion during freezing c. evaporative cooling

10. Laundry detergent typically has a pH of 3 which indicates a(n) ___ solution?

a. acidic b. basic c. neutral

11. The use of ___ helps to maintain a certain pH in our bodies maintaining homeostasis.

a. buffers b. bases c. acids

12. The ___ property of water removes heat helping to cool your skin through sweating.

a. capillary action b. evaporation c. cohesion