The pH Scale and Indicators

The pH Scale

pH- “potency hydrogen” [H + ], a measure of how acidic or basic a solution is, the concentration of H + ions pH SCALE- a logarithmic scale ranging from 0 (1x10 0 very acidic) to 14 (1x very basic or alkaline) NEUTRAL- neither acidic or basic, pH of 7

pH in Our Lives

Soil pH – pH of the soil can vary considerably, depending on the type of rock in the area – Has a huge effect on what types of plants can grow where – Soil pH can sometimes be altered to improve growing conditions (ex. adding compost makes soil more acidic)

Our skin – slightly acidic (which wards off acne bacteria) – “pH balanced” does not mean 7 Swimming pools need a pH of

Metal toxins in soil – ex. from batteries, lead factories – ACID LEACHING (removal by neutralization) – PHYTOREMEDIATION (removal by sponges)

Indicators

INDICATORS: __ME60 __ME60

Disadvantages of indicators: – Only identifies a substance as an acid or base, does not tell you pH – Coloured solutions are difficult to test

Other measurements: – LITMUS PAPER- wide range pH paper, tells you pH – pH METER- electrode attached to digital display

RED CABBAGE SCIENCE EXPERIMENT: – – – flk&feature=related flk&feature=related ACIDS, BASES, AND PH SCALE SONG: I&feature=related I&feature=related

Neutralization Reaction In order to neutralize (have a pH of 7) an acid or a base, we can use a neutralization reaction. Acid + Base Salt + Water By adding an acid to a base, the products are salt and water. Both of which are neutral. Warning: if you add too much acid or too much base, the resulting substance won't be neutral!

Practice: Complete “The pH scale” worksheet in your booklet (including the Neutralization Reaction portion at the bottom)