9..2 Indicators And PH Scale

Question 1

What to use to show the presence of acids/alkaline (distinguish)

Answer 1

Indicators

Question 2

What are 2 kinds of indicators that DISTINGUISH acids/alkaline

Answer 2

Natural indicators and litmus

Question 3

How does red cabbage extract work as a natural indicator

Answer 3

Contains pigments that change colour in the presence of an acid/alkaline

Question 4

What colour is red cabbage extract in acidic/alkaline solutions

Answer 4

Pink in acidic
Green in alkaline

Question 5

What’s litmus

Answer 5

A mixture of pigments extracted fr lichen

Question 6

How does litmus distinguish acids/alkaline

Answer 6

Shows diff colours in acidic/alkaline conditions

Question 7

What forms are litmus available in

Answer 7

Solution and paper

Question 8

What colours do litmus paper come in

Answer 8

Red, blue

Question 9

How to prepare litmus paper

Answer 9

Soak strips of filter paper in litmus solution and dry before use

Question 10

What colour litmus are used to test acids/alkaline

Answer 10

Acid: blue turns red
Alkaline: red turns blue

Question 11

What do we use to show HOW acidic/alkaline substance is

Answer 11

Universal indicator

Question 12

How does universal indicator work

Answer 12

diff colours depending on degree of acidity/alkalinity

Question 13

What is the paper form of universal indicator

Answer 13

PH paper

Question 14

Explain the PH scale

Answer 14

Acidic 0-6, lower —> more acidic
Neutral 7
Alkaline 8-14 lower —> less alkaline

(More acid Less acid less alkaline More alkaline)

Question 15

Arrange these from most to least acidic
Cola, orange juice, Black coffee, sulphuric acid

Answer 15

Sulphuric acid, cola, orange juice, black coffee

Question 16

Arrange these from most to least alkaline
Glass cleaner, limewater, detergent, drain cleaner

Answer 16

Drain cleaner, limewater, glass cleaner, detergent

Question 17

Universal indicator only gives a rough measurement. What are more accurate ways to measure pH value?

Answer 17

PH meter
-probe connected to digital display

PH sensor connected w data-logger
-record,analyse, monitor changes

Question 18

Sum up- list the 2 indicators that DISTINGUISH and 4 indicators that show HOW acidic/alkaline

Answer 18

DISTINGUISH
1. natural indicators
2. Litmus

HOW
1. Universal indicator
2. PH paper
3. PH meter
4. PH sensor connected w data logger

Question 19

Advantages of pH meter

Answer 19

Accurate, reuse, deep colour

Question 20

Disadvantages of pH meter

Answer 20

Expensive, less convenient