Chapter 2
Part 2: Reactions & Inorganic Compounds
Chemical Reactions • Reactants Products
• Eg. 6CO2 + 6H2O C6H12O6 + O2
• Some reactions are reversible:
• Eg. 3H2 + N2 2NH3
• Chemical equilibrium: point at which forward and reverse reactions offset one another exactly
• Reactions still occurring, but no net change in concentrations of reactants/products
3 Patterns of Chemical Reactions 1. Synthesis = combining atoms/molecules to form larger,
more complex molecule
A + B AB
Anabolic reactions
2. Decomposition = breaking apart molecules
AB A + B
Catabolic reactions
3. Exchange Reaction = bonds made/broken to exchange parts
AB + C AC + B
AB + CD AD + CB
Factors influencing rate of reaction: Temperature: temp, rate
Concentration: reactants, rate (as reactants , rate will )
Particle size: small particles move faster
Catalysts: increase rate of reactions (enzymes)
Two classes of chemicals: 1. Inorganic compounds: no carbon
Small, simple
Water, salts, acids, bases
2. Organic compounds: contain carbon
Usually large, complex
Carbs, lipids, proteins, nucleic acids
Water Polar molecule = shares electrons
(e-), but not shared equally
Electrons spend more time around oxygen (very electronegative)
Oxygen end of H2O slightly -
Hydrogen end of H2O slightly +
Hydrogen bonds in water Attraction between (+) end of polar molecule with the
(-) end of another polar molecule
Properties of Water 1. High heat capacity: absorb/release heat;
maintain constant temps
2. High heat of vaporization: liquid gas; evaporative cooling
3. Polar solvent: dissolve substances; universal solvent
4. Reactivity: involved in many chemical reactions
5. Cushioning: protect, cushion organs
Salts Ionic compounds
Dissolve in H2O
Electrolytes – conduct electrical current in solution
Common salts in body: NaCl, CaCO3, KCl, calcium phosphate (bones)
Acids & Bases Acid: release hydrogen (H+) ions (proton donor)
HCl H+ + Cl-
Sour taste
Eg. acetic acid, carbonic acid
Base: take up H+ ions (proton acceptor)
NaOH Na- + OH-
Bitter taste, feel slippery
Eg. bicarbonate ion (HCO3-), ammonia (NH3)
pH Scale Acids: pH < 7
Neutral pH = 7
Bases: pH >7
Buffers Maintain homeostasis by resisting changes in pH of
body fluids
Blood pH: 7.35 – 7.45
Release H+ ions when pH rises; bind H+ ions when pH drops
Weak acids or bases
Major buffer: carbonic acid – bicarbonate system
H2CO3 (carbonic acid) HCO3- (bicarbonate) + H+