Bio Exam Prep

CHEMISTRY SEMESTER TWO EXAM NOTES

CHAPTER 10- WATER

Water and living things

• Cellular Respiration

C6H12O6(aq) + 6O2 (g)                     6CO2(g) + 6H2O(l) + energy[pic 1]

• Photosynthesis[pic 2]

6CO2(g) + 6H2O(l)                C6H12O6(aq) + 6O2 (g)[pic 3][pic 4]

WATER [pic 5][pic 6]

Solid (ice)                                        Liquid (water)                Gas (water vapour)

[pic 7][pic 8][pic 9]

        [pic 10][pic 11][pic 12][pic 13][pic 14]

[pic 15]

[pic 16]

Specific Capacity

• Amount of energy required to raise the temperature of a substance of 1g by 1oC.
• Water has a high heat capacity- it take more energy to heat up 1g of water than 1g of anything else (eg. sand)
• Amount of energy required to raise temp= SHC x m x ∆T[pic 17][pic 18][pic 19][pic 20]

[pic 21]

Water as a solvent

Solvent + solute = solution

• A solution must be:

• Homogenous- solvent and solute distributed evenly throughout solution
• Solute particles must be too small to be seen
• Transparent in visible light.

Why do substances dissolve?

• When one substance dissolves into another, the following occurs:

• The particles of the solute are separated from one another
• The Particles of the solvent of separated from on another
• The solvent and solute particles attract each other

• A solute will dissolve if the attraction between the solute and solvent particles is strong enough to compete with the solute- solute and solvent-solvent forces of attraction

All substances that dissolve in water have ionic or polar covalent bonding

Miscible- two liquids placed in same container they do not form separate layers

Immiscible- form separate layers

1) Dissolving Polar Covalent Compounds

        a) Hydrogen Bonds[pic 22]

        CH3CH2OH(l)                             CH3CH2OH(aq)                             [pic 23]

[The more –OH groups the more likely it is able to dissolve in water]

• H bonds of water break to make H- Bonds with the –OH group of another to dissolve it.

        b)  Forming Ions [pic 24]

                              HCl2(l)  +   H2O(l)                             H30+(aq)   +  Cl-(aq)[pic 25]

2) Dissolving Ionic Compounds

• Solid ionic compounds contain + and - ions.
• In water the H+ is attracted to the – anion [pic 26][pic 27][pic 28]

           The O2-  is attracted to the + cation

[pic 29]

[pic 30][pic 31]

This is called a Dissociation Process

Eg.

NaCl(s)          h20(aq)     Na+(aq)  +  Cl-(aq) [pic 32]

When an ionic compound dissolves in water, producing separate cations and anions.

I.e. dissociated from the lattice.

SOLUBILTY GUIDE FOR COMMON IONIC COMPOUNDS