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Biology. Properties of Water And Acids/Bases (pH) SB1.d. Explain the impact of water on life processes. Why is water important to humans?. 2/3 of the weight of a cell is WATER! Look at all the important uses of water in the body…. What properties of water make it so useful and important?.

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Biology

Biology

Properties of Water

And

Acids/Bases (pH)

SB1.d. Explain the impact of water on life processes.


Why is water important to humans

Why is water important to humans?

  • 2/3 of the weight of a cell is WATER!

  • Look at all the important uses of water in the body…


What properties of water make it so useful and important

What properties of water make it so useful and important?

  • Water is polar:

    a. Has a slight charge on each end.

    b. One side of water is “+” and the other side is “-”

    c. This polarity enables water to dissolve many substances


What properties of water make it so useful and important1

What properties of water make it so useful and important?

2. Water is called “Universal solvent”:

a. Differences in charges pulls/pushes substances apart so they dissolve


What properties of water make it so useful and important2

What properties of water make it so useful and important?

3.Water is cohesive & adhesive which creates surface tension

Cohesive- water molecules stick to each other

Adhesive- water molecules stick to other surfaces

Surface tension- like a skin of water

Ex: how some insects walk on water

Surface tension created by cohesiveness of water


What properties of water make it so useful and important3

What properties of water make it so useful and important?

4. Water moves by capillary action

  • Capillary action- water molecules pull each other up against gravity

  • This is how trees get water from their roots to their leaves.


What properties of water make it so useful and important4

What properties of water make it so useful and important?

5. Water exhibits evaporative cooling:

  • removes heat when it evaporates from a surface- ex: sweating

  • Stores heat- helps maintain earth’s temperature


What properties of water make it so useful and important5

What properties of water make it so useful and important?

6. Water expands during freezing:

  • ex: rocks broken up by ice to create soil

  • Also less dense when frozen so floats on liquid water- prevents entire ponds from freezing- which would kill animals in pond


So why is water so important to life

So why is water so important to LIFE?

  • Used in chemical reactions in cells

  • Helps create soil

  • Plants use to make food for all

  • Used to dissolve materials needed in cells

  • Helps maintain Earth’s temperature


What is the ph scale

What is the pH scale?

Measures the concentration of Hydrogen (H+) ions in a solution


Biology

What is an ACID?

1. release H+ when mixed with water

2. 0-6 on pH scale

3. Sour, corrosive

4. Always have H at front of formula

5. Ex: HCl is hydrochloric acid

What is a BASE?

1. release hydroxide (OH-) when mixed with water

2. 8-14 on pH scale

3. Bitter, slippery, usually in cleaners

4. Always have OH at end of formula

5. Ex: NaOH is sodium hydroxide

Neutral: H+ ions and OH- ions are equal so it is neutral. They are 7 on pH scale.


What s the ph scale got to do with biology

What’s the pH scale got to do with Biology?

  • Chemical reactions in cells release and absorb hydrogen- this can change pH.

  • If pH levels in body are not maintained, electrical chemistry in body doesn’t work- can lead to sickness.


What is a buffer

What is a buffer?

1. Body chemicals that prevent sharp changes in pH so keep solution neutral

2. Help to control pH in blood, digestive tract, etc. to maintain homeostasis


Biology

  • Your stomach juices measure 2 on the pH scale, it is a(n) ___ solution.

  • a. acidic b. basic c. neutral

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

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

  • Water has a slight charge on each end. This property makes water a great solvent. This property is called

    • Polarityb. Capillary actionc. Frost wedging

  • 4. Insects can walk on H2O & paper clips are able to float on H2O because of water’s

    • Surface tension from hydrogen bonds

    • Cohesion with other molecules

    • Adhesion with its own water molecules

    • High specific heat

  • 5. Trees are able to move water from the roots to the leaves by the property of water known as

    • Polarityb. Capillary actionc. Surface tension

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

  • a. capillary action b. evaporation c. cohesion


Match these pictures with their water properties

Match these pictures with their water properties:

1.

6.

  • Cohesion & adhesion

  • Capillary action

  • Evaporative cooling

  • Surface tension

  • Expansion during freezing

  • Polarity- universal solvent

2.

4.

5.

3.


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