Chemical Reactions & pH Notes

Chemical Reactions and Energy

  • All chemical reactions in the body involve potential energy.

  • Activation energy is required to break initial bonds.

  • Once activation energy is applied, bonds are broken and reassemble.

Organic Compounds

  • Organic compounds always contain carbon (C) and hydrogen (H).

  • They usually contain oxygen (O).

Hydrophilic Substances

  • A hydrophilic substance can dissolve in water.

Dehydration Synthesis and Hydrolysis

  • Understanding dehydration synthesis and hydrolysis is essential.

  • You don't need to write out the processes, but should know them.

  • Carbohydrates have the formula C<em>xH</em>2xOxC<em>xH</em>{2x}O_x, showing similar formulas.

Enzyme Influence

  • Under the influence of enzymes (catalysts), molecules form bonds to create new compounds.

  • Example: Two molecules form a bond to create sucrose (table sugar).

Salts

  • Anything that does not donate H+H^+ or OH−OH^- in water is a salt, such as potassium chloride (KCl).

pH Scale

  • The pH scale ranges from 0 to 14.

  • It is an inverse scale: lower numbers indicate higher concentrations of hydrogen ions (H+H^+).

Exponential changes in hydrogen concentration

  • Examples of hydrogen concentrations relative to neutral pH:

    • pH 6: 10−610^{-6} M

    • pH 5: 10−510^{-5} M

    • pH 4: 10−410^{-4} M

Scientific Notation and Logarithmic Scales

  • Logarithmic scales like pH indicate a tenfold change between numbers.

  • A change from one pH number to the next represents a tenfold change.

  • For example, a change from pH 6 to pH 4 is a hundredfold change.

Hydrogen Concentration and pH

  • High concentrations of hydrogen ions correspond to low pH values.

  • Low concentrations of hydrogen ions correspond to high pH values.