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Acids and Bases. Definitions. Our definitions of acids and bases come from the work of Arrhenius in 1884. There are other definitions you may learn later. Acids. Acids are compounds that ionize to form H + ions. Ex. HCl H + + Cl - is the ionization reaction for hydrochloric acid.
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Definitions • Our definitions of acids and bases come from the work of Arrhenius in 1884. There are other definitions you may learn later.
Acids • Acids are compounds that ionize to form H+ ions. Ex. HCl H+ + Cl- is the ionization reaction for hydrochloric acid. • Some properties are: taste sour, can burn skin, turns litmus paper red and Bromothymol blue yellow, reacts with metals.
Simple Acid Naming • Acids are easily formed with hydrogen and the group 17 halogens. This are easy to name. • Ex 1. HF – hydrofluoric acid • Ex 2. HCl – hydrochloric acid • ‘Hydro-’ is added to the front of the name and the end of the non-metal is changed to ‘-ic’. Finally the name ends with the word acid.
Bases • Bases are easily formed between group 1 metals and the polyatomic ion hydroxide • Bases are compounds that ionize to form OH- ions. Ex. NaOH Na+ + OH- is the ionization reaction for sodium hydroxide. • Some properties are: taste bitter, can burn skin, feels slippery, turns litmus paper blue and Bromothymol blue blue, reacts with some metals (Al).
Naming Simple Bases • Simple bases are named the same way as polyatomic ionic compounds. • Ex 1). NaOH – sodium hydroxide • Ex 2). KOH – potassium hydroxide.
Indicators • These are substances that change colour in the presence of an acid or base. • Ex 1). Litmus Paper – it turns red with an acid and blue with a base. • Ex 2). Bromothymol Blue – it turns yellow with an acid and blue with a base.
pH scale • This scale tells you the strength of any gven acid or base. • It runs from 1-14. • 1 is a strong acid and 14 is a strong base with 7 being neutral (water is a 7). • So, 1-6.9 are acids and 7.1-14 are bases. • It is derived from the concentration of H+ in the solution. This is not to be confused with the pOH scale which it the opposite of the pH scale.
Neutralization Reactions • This is the reaction when acids and bases are mixed. For our class we will only look at a strong acid mixed with a strong base. • General Reaction: Acid + Base salt + water • Ex 1). HCl + NaOH NaCl + H2O • Ex 2). KOH + HBr KBr + H2O
Questions • Pg. 218 #2,3 • Pg. 225 #1-3 • Pg. 230 #1-2 • Pg. 236 #1-3