acids and alkalis - Research at ASSAf

(1)

QUESTONLINE.ORG.ZA Quest Vol. 17 No. 2 | 2021 5

Acid: The bottom end of the scale

Drain Cleaner Bleach Ammonia

Soap

Baking Soda

Seawater Pure Water

Urine (average) Black Coffee Tomato Juice

Battery Acid Stomach Acid

Soda

C

BY NC ND

ACIDS, ALKALIS, AND THE pH SCALE

14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 NEUTRAL

A C I D I C A L K A L IN E

H⁺ CONCENTRATION

(in moles per litre)

1 × 10

^-14

1 × 10

^-13

1 × 10

^-12

1 × 10

^-11

1 × 10

^-10

1 × 10

^-9

1 × 10

^-8

1 × 10

^-7

1 × 10

^-6

1 × 10

^-5

1 × 10

^-4

1 0.1 0.01 0.001

The pH scale is a way of gauging the acidity or alkalinity of a solution. It is calculated using: pH = -log₁₀[H⁺]. Adding an acid to water increases the H⁺ (H₃O⁺) concentration, and decreases the OH^- concentration. An alkali does the opposite.

pH

1 0.1 0.01 0.001

1 × 10

^-4

1 × 10

^-5

1 × 10

^-6

1 × 10

^-7

1 × 10

^-8

1 × 10

^-9

1 × 10

^-10

1 × 10

^-14

1 × 10

^-13

1 × 10

^-12

1 × 10

^-11

OH^- CONCENTRATION

(in moles per litre) EVERYDAY EXAMPLE

Lemon Juice Antacid Tablets

RedOrangeYellowTurquoiseBluePurple

Green

ACIDS AND ALKALIS | THEME

(2)

Academy of Science of South Africa (ASSAf)

ASSAf Research Repository http://research.assaf.org.za/

A. Academy of Science of South Africa (ASSAf) Publications D. Quest: Science for South Africa

2021

Quest Volume 17 Number 2 2021

Academy of Science of South Africa (ASSAf)

Cite: Academy of Science of South Africa (ASSAf), (2021). Quest: Science for South Africa, 17(2). [Online] Available at: http://hdl.handle.net/20.500.11911/191

http://hdl.handle.net/20.500.11911/191

Downloaded from ASSAf Research Repository, Academy of Science of South Africa (ASSAf)