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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 substances Solvent – Substance that does the dissolving (there is more of this one)
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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.
Solution – Homogenous mixture of 2 or more substances Solvent – Substance that does the dissolving (there is more of this one) Solute – Substance that is dissolved
How do you know if something will dissolve in something else?
Like Dissolves Like! • Polar dissolves in polar • Nonpolar dissolves in nonpolar • Nonpolar doesnot dissolve in polar (polar means the molecule has a + & – end) http://www.kentchemistry.com/links/bonding/LikeDissolveslike.htm
What Can Speed up the Solution Rate? • 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.
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? • High Heat Capacity – prevents sudden changes in body temp. • Reactivity – it is a reactant in many of the chemical reactions in our body (food digestion) • Solvent Properties– most reactions in the body don’t happen unless the reactions are dissolved in water.
+ 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. Called Dissociation. http://www.kentchemistry.com/links/bonding/LikeDissolveslike.htm
Hydrogen Bonds The 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.