BCH1001 Electrolytes, Acids, Bases and Salts (6) PDF

Biochemistry & Cell Biology BCH1001 Electrolytes – acids, bases and salts Dr Patricia Johnson [email protected] Some basic chemistry an atom or molecule which has gained or lost one or more of its electrons, giving it...

Biochemistry & Cell Biology BCH1001 Electrolytes – acids, bases and salts Dr Patricia Johnson [email protected] Some basic chemistry an atom or molecule which has gained or lost one or more of its electrons, giving it a net positive or negative electrical charge is called an ion (charged particle) Positively charged: cation Negatively charged: anion  What is an electrolyte? All fluids of living systems contain dissolved ions and molecules For example, blood contains sodium and chloride ions, glucose molecules and many other species Ions in water can carry electricity An electrolyte is a substance that dissolves in water to give a solution of ions that can conduct an electric current Ions in the skin enable an electrocardiogram to be done which records the electrical activity of the heart What is an electrolyte?  Any compound that can dissociate (break down) in solution to give ions is an electrolyte e.g. acids, bases and salts  Hydrochloric acid (HCl), sodium hydroxide (NaOH) and sodium chloride (NaCl) are all good electrolytes yielding anions and cations:  ACID: HCl H+ + Cl-  BASE: NaOH Na+ + OH-  SALT: NaCl Na+ + Cl-  An electrolyte in a solution is concentrated if it has a high concentration of ions, or dilute if it has a low concentration What is an electrolyte? In physiology, the primary ions of electrolytes are sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl-) and phosphate (PO43-) These are very important in cell membranes where they have their own ion channels, for controlling hydration in the body and they are critical for nerve and muscle function Sometimes, electrolyte balance in the body is disturbed and electrolyte-containing substances must be given by IV  What are acids and bases? An acid is a hydrogen ion donor, so lots of H+ ions A base is a hydrogen ion acceptor, so few H+ ions Hydrogen ion (H+) = proton H+ ions are always attached to something else in solution; they cannot Acid rain can do exist independently real damage to the environment  What are acids and bases? An acid is a hydrogen ion donor, so lots of H ions + H+ H+ +H+ H H+ +H + H H+H+ H+ A base is a hydrogen ion acceptor, so few H+ ions H+ ions are always attached to something else in solution; they cannot exist independently  What are acids and bases? Acids turn blue litmus paper red and have a sour taste e.g. vinegar, lemons Bases turn red litmus paper blue and have a bitter taste and soapy feel e.g. chalk, milk of magnesia Litmus test Strong acids are almost 100% ionised in solution e.g. hydrochloric acid (HCl), nitric acid (HNO3) Weak acids are only ionised to a small extent (< 50%) in solution e.g. acetic acid (CH3COOH) Strong Acids Strong Bases Perchloric acid Potassium hydroxide HClO4 KOH Hydrochloric acid Sodium hydroxide HCl NaOH Sulfuric acid Calcium hydroxide H2SO4 Ca(OH)2 Nitric acid Lithium hydroxide HNO3 LiOH Acids and Bases https://www.youtube.com/watch?v =DupXDD87oHc&list=PL4Ooa7gc jW8SjrmESk32EDZP-clTYL7WY &index=13&t=0s What are salts? Salts are the products of reactions between acids and bases Acid + base salt + water HCl + NaOH NaCl + H O 2 Cl - + Na+ NaCl They are ionic compounds and are solid crystals at room temperature They are strong electrolytes since they are 100% dissociated in water back to their ions  What is pH? pH is a term used to describe the level of acidity or basicity (alkalinity) of a solution  pH = -log [H+] 10 The range is 0-14  pH < 7, acidic  pH > 7, basic (alkaline)  pH = 7, neutral  If the pH changes from 2 to 3, that’s a 10 times decrease in [H+]!  The range in the body is 1-2 (stomach acid) to 6-8 (urine, blood and saliva) to 9 (pancreatic juice) Each pH unit represents a tenfold change in H3O+ The pH of our blood is normally controlled to within a few tenths of a pH unit by our body chemistry. If our blood pH changes as much as half a pH unit, serious illness will result. Proper skin pH is essential for a healthy complexion. The pH of one's stomach directly affects the digestive process. What is pH scale? pH = -log10 [H+] Log scale therefore a slight change in value has very significant effects….. Electrolytes and pH-Useful websites www.medicinenet.com/electrolytes/article.htm www.chemtutor.com/acid.htm