Part 2: Reactions & Inorganic Compounds Chemistry Comes Alive Part 2: Reactions & Inorganic Compounds

Chemical Reactions Reactants  Products Some reactions are reversible: 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 Synthesis = combining atoms/molecules to form larger, more complex molecule A + B  AB Anabolic reactions Decomposition = breaking apart molecules AB  A + B Catabolic reactions 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: Inorganic compounds: no carbon Small, simple Water, salts, acids, bases 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 High heat capacity: absorb/release heat; maintain constant temps High heat of vaporization: liquid  gas; evaporative cooling Polar solvent: dissolve substances; universal solvent Reactivity: involved in many chemical reactions 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+