warm up 4/2 we know that our bodies need water, but how is the water used? make a list of what that...

Warm Up 4/2

We know that our bodies need water, but how is the water used?

Make a list of what that your body uses water for.

Intro to Solutions

Solution – Homogenous mixture of 2 or more substancesSolvent – Substance that does the dissolving (there is more of this one)Solute – Substance that is dissolved

What solutes could be dissolved into this solvent?

Can these two solids dissolve into each other?

What is the solvent and what are the solutes?

Can a liquid be dissolved in a gas?

How do you know if something will dissolve

in something else?

Like Dissolves Like!• Polar dissolves in polar • Nonpolar dissolves in nonpolar• Nonpolar does not dissolve in polar

http://www.kentchemistry.com/links/bonding/LikeDissolveslike.htm

(polar means the molecule has a + & – end)

What Can Speed up the Solution Rate?

1. Agitation (stirring) – causes the molecules to collide more.

2. Greater surface area (crushing or grinding) – more solute for the solvent to act on.

3. Temperature – Kinetic energy (movement) causes molecules to collide more.

Sugar Lab1. Fill all beakers with 200 mL of

water2. We will test all 3 factors alone

(don’t do 2 factors at once)3. Drop sugar in & time each factor4. Don’t do anything to the “control”5. Don’t let the water boil (100°C)6. Write your observations and times

Water – Universal Solvent

You know that your body needs water to stay alive. It makes up most of your cells and blood, and can be found throughout your body. But what makes water so special? Why isn’t a different liquid compound used in its place?

Quickly discuss this question with those near you.

Why Water?1.High Heat Capacity – prevents sudden

changes in body temp.2.Reactivity – it is a reactant in many of

the chemical reactions in our body (food digestion)

3.Solvent Properties – most reactions in the body don’t happen unless the reactions are dissolved in water.

When you’re ridin’ in a Chevy and you feel something heavy…

Electronegativity! O is more

electronegative than H, so the O atom gets the shared

electrons most of the time.

+

-

The water molecules pull the salt ions away.

http://www.kentchemistry.com/links/bonding/LikeDissolveslike.htm

Called Dissociation.

Hydrogen BondsThe polar ends of the water molecules attract the opposite ends of other water molecules.

Hydrogen Bond Activity

Question: How many drops of water do you think the surface of a penny can hold? Make a prediction on your paper.

Procedure: Use a pipette to drop water onto a penny to find out. Try to use a level surface.

Left Side – On Your Own

Create your own left side for this lesson that demonstrates that you understand the ideas we learned in your own creative way.