This document summarizes key concepts about chemical reactions, acids and bases, and chemical components of cells. It discusses how catalysts lower the activation energy of reactions without being consumed; how acids and bases dissociate in water to release ions; how pH measures hydrogen ion concentration and blood pH is tightly regulated; and the main inorganic substances in cells including water, oxygen, carbon dioxide, and inorganic salts.

1. section 3 of chapter 2
chemical reactions

2. Chemical Reactions

3. activation energy: energy required to start a reaction
A catalyst reduces the amount of energy needed to
initiate a reaction.
Catalysts increase the rate of reactions, but are not
consumed by the reaction- reusable

4. Acids, Bases, and Salts
Electrolytes – are substances that dissociate in water to release ions.
Example: NaCl → Na+ + Cl-

5. Acids - electrolytes that dissociate to release protons (H+) in water
Example: HCl→ H+ + Cl-
Bases- electrolytes that absorb H+ from water, or
electrolytes that dissociate to release hydroxide ions (OH-) in water
Examples: NaOH→ Na+ + OH-
Salt – electrolyte formed by the reaction between an acid and base
Acid + Base → Salt + water
Example:
HCl + NaOH → NaCl + H2O

6. acid and base concentrations
pH
pH measures the concentration of hydrogen ions [H+] in a solution.
As pH decreases, [H+] increases = solution is more acidic
acidic property increasing
pH
0
alkaline property increasing
7
neutral
14

7. Small changes in pH reflect large changes in [H+]
change of 1 pH = 10 fold change in [H+]
change of 2 pH = 100 fold change in [H+]
change of 3 pH = 1000 fold change in [H+]

8. Blood
Average blood pH = 7.35 - 7.45
Acidosis = blood pH less than 7.3
Symptoms include fatigue, disorientation, and difficulty breathing.
Alkalosis = blood pH greater than 7.5
Symptoms include agitation and dizziness
Blood contains several buffers
Buffer = resists changes to pH

9. Chemical components of cells
Organic Vs. Inorganic
Molecules
Organic molecules
Compounds with carbon
May form macromolecules
Includes proteins, carbohydrates, lipids, nucleic acids
Inorganic molecules
Compounds that lack Carbon (exception is CO2)
Usually dissociate in water

10. Inorganic Substances
Water (H2O)
2/3 of weight in a person
Transports gasses, nutrients, wastes, hormones, ect.
Oxygen (O2)
Used in cellular respiration
Carbon Dioxide (CO2)
Waste of metabolic reactions
Inorganic Salts
Na+, Cl-, K+, Ca2+, HCO3-, PO42-
End of Section 3, Chapter 2