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pH & Buffers. Hydrogen ion concentration increasing. 0 1 2 4 5 6 7 8 9 10 11 12 13 14.
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pH & Buffers
Hydrogen ion concentration increasing 0 1 2 4 5 6 7 8 9 10 11 12 13 14 Acidic Neutral Basic Hydroxide ion concentration increasing pH (power of hydrogen): relative concentration of H+ ions in a solution • Scale 0-14…used to indicate strength of acids and bases • Low pH indicates a high concentration of H+ • High pH indicates a low concentration of H+ pH scale
Acid: a solution in which Hydrogen ions (H+) are in higher concentration than Hydroxide ions (OH-) pH is less than 7 • Acid molecules disassociate in water, thus they release H+ in solution • HCl H+ + Cl- • Strong acids (pH of 0-2)= stomach acid (HCl) and battery acid (H2SO4) • Weak acids (pH of 3-6)= lemon juice, vinegar, rainwater • Litmus paper will be red
Base: a solution in which Hydroxide ions (OH-) are in higher concentration than Hydrogen ions (H+) pH is more than 7 • Disassociate in water and release OH- in solution • NaOH Na+ + OH- • Strong bases (pH of 12-14)=solutions of lye (NaOH) and oven cleaner (KOH) • Weak bases (pH of 10-12)=bicarbonate solution • Litmus paper will be blue
Buffer: substance that resists a change in pH when either H+ or OH- are added • Why do we need buffers? • Control pH in the body • Example: carbonic acid (H2CO3) in human blood
pH, Buffers, & Homeostasis • Controlling pH in the body using buffers is a form of maintaining homeostasis • Homeostasis:the ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes.
Homeostasis in Humans • Human blood pH = 7.4 • Anything below 7.0 or above 7.8 can lead to death • Human urine pH = ranges from 4.5 to 8.0 depending on person’s diet • High protein foods (meat, fish, poultry, eggs) and most carbohydrates (breads, pastas, grains) are acid-forming • Most fruits and vegetables are base-forming
Vocabulary • pH • Acid • Base • Neutral • Buffer • Homeostasis