pH

A- What is pH?

A1.pH represents the concentration of H+ in a solution

A2.pH = the power of Hydrogen

pH = -log10 [H+]

A3.Lower pH means higher H+

concentration

B- What is pH used for?

B1.pH tells how acidic or basic a solution is

B2.Very acidic solution has low pH value

B3.Very basic solution has high pH value

C1. pH scale lies from 0 (very acidic) to 14 (very basic)

C2. Neutral solution has pH =7

D- pH and soil

D1.Corn and small grains prefer pH 5-6 (acidic? neutral? Or basic?)

D2. it’s slightly acidic- D3.Potatoes and

blueberries prefer pH < 5 (acidic? neutral? Or basic?)

-D4. it’s basic

E- Hydrangea color

E1- Blue flowers if in acidic soil (pH <5.5)

E2- Pink flowers if in basic soil (pH> 6.5)

F- pH and Cosmetics

F1. Our skin has a pH of 5.5F2. What can you infer about our skin?F3. Why is it necessary to have pH 5.5?

F4.High pH cosmetic products can remove layers of dead cells, making skin look brighter and clearer. Occasional use only

G. How to test pH?

pH paper

G2.IndicatorsG1.pH meter

Red cabbage juice

H. pH paperH1. Litmus paper:

H2. Litmus: an indicator from lichen

H3. 2 kinds: blue and red

H4. Acids turns blue litmus to red

H5. Bases turns red litmus to blue

I. pH paper with universal indicator

I1.Paper dipped in mixture of many indicators that produce different color at different pHI2.Acids turn pH paper to red/orange colorI3.Bases turn pH paper to blue/green color

J- Natural indicator

J1. Natural indicator: such as red cabbage juice

K. Other indicators

1 7 14

K1. Color of bromothymol blue =? when pH =13

Lab• Read the pH of

common household substances using both:

-pH paper- natural indicator

(i.e. red cabbage juice)