pH and some other stuff

Define the term buffer and explain in general terms how buffers work.

A buffer is a solution, the pH of which changes only slightly when moderate amounts of either acid or base are added. A buffer maintains an almost constant pH by neutralising moderate amounts of acid or base that are added, it does this by having components that neutralise either base of acid.

Outline the chemical characteristics of acids and bases.

Acid Sour taste Cause colour changes in chemical indicators Can be corrosive (strong acids.) Can be neutralised by bases to form a salt and water. Base Bitter Cause colour changes in chemical indicators Can be corrosive (strong bases.) Can be neutralised by acids to form a salt and water.

Define the terms acidosis and alkalosis, and outline the causes, physiological effects and treatment for each condition.

Acidosis - pH decreases below 7.35. Caused by hypoventilation , loss of bicarbonate ions (diarrhoea) accumulation of metabolic acids, renal dysfunction (kidney failure). - Reduced activity of the central nervous system.if drops below 7 progressive disorientation, coma, death. - ventilation therapy/ intravenous administration of bicarbonate ions/ correction of underlying cause. Alkalosis - pH increases above 7.45. Hyperventilation loss of hydrogen ions (vomiting), excessive intake of alkaline material (antacids), certain diuretics. - over excitation of nervous system and peripheral nerves, if above 7.8 progressive spasms or convulsions, leads to death by respiratory arrest/ correction of cause.

Define the terms acid, base and pH, giving examples to illustrate the definitions.

An acid is a substance that can donate protons in aqueous solution (water). Lemon juice, vinegar.A base is a substance that cannot accept protons in aqueous solution. Bicarbonate. pH is a measure of the number of free hydrogen ions in a solution. pH = potential of Hydrogen.

List the pH of blood and main body secretions.

Blood- 7.35-7.45 Gastric juice- 1.2-3.0 Bile- 7.6-8.6 Pancreatic juice- 7.4-8.2 Sweat- 5.0 Urine- 4.5-8.3 Vaginal secretions- 3.5-4.5 Semen- 7.4-7.8

List the main buffers in the human body, and illustrate how each of them operate.

Carbonic acid/bicarbonate buffer system - operates primarily in blood, each part converts the incoming base/acid into the opposite converter. Phosphate buffer system - primarily within cells rather than body fluid. Similar to carbonic/bicarbonate in this case dihydrogen phosphate converts into the monohydrogen phosphate converter and vis versa. Protein buffer system- in both blood and cells. The organic acids, and functional group work together to neutralise incoming bases, and the amino group neutralise incoming acids

Describe the pH scale used for the measurement of hydrogen ion concentration

Defined as the negative logarithm of the hydrogen ion concentration in grams/litre. The lower the number the higher the acidity, the higher the number the higher the alkalinity.

Summarise the homeostatic regulation of pH of the internal environment.

Homeostasis is maintained in the body through buffering systems. See next question for breakdown.

List 6 important acids and 1 base in the human body, and describe their functions.

Hydrochloric acid - Gastric secretions Fatty acids - Components of fats Deoxyribonucleic acid - DNA Amino acids - Components of protein Lactic acid- Formed by anaerobic metabolism of carbohydrates Ribonucleic acid - RNA Bicarbonate ion - Components of bile and pancreatic secretions.

Define the terms solution, solute and solvent.

Solution - uniform mixture of atoms, ions or molecules of 2 or more substances(1 is quite often liquid.) Solute - in a solution the substance that is being mixed or dissolved Solvent - the substance that causes the dissolution.

Distinguish between strong and weak acids.

The strength of an acid depends on its degree of ionisation in aqueous solution.

Describe the structure of the water molecule and its resulting ability to act as a good solvent.

Water molecules have a polar arrangement of the oxygen and hydrogen atoms—one side (hydrogen) has a positive electrical charge and the other side (oxygen) had a negative charge. This allows the water molecule to become attracted to many other different types of molecules. Water can become so heavily attracted to a different molecule, like salt (NaCl), that it can disrupt the attractive forces that hold the sodium and chloride in the salt molecule together and, thus, dissolve it.