Question

how to determine which is base and which is alkali if question is asked in paper​

Answer 1

Answer:

base

• A substance used to neutralize acid is called a base.
• Eg of base: zinc hydroxide and copper oxide.
• Bases do not dissolve in water

alkali

• Alkali is a base that dissolves in water.
• Not all bases are alkali but all alkali is base.
• It releases OH- ions, accepts a proton
• Eg: potassium hydroxide, sodium hydroxide

Answer 2

Answer:

This simple experiment involves testing a variety of substances to see if they are acidic or alkaline. Litmus paper is used as the indicator

This experiment is most suitable for introductory level chemistry and could be done as a circus with pairs/small groups of students moving from one station to another.

A discussion of the meaning of the words acid, alkali and neutral could be a good way to introduce the experiment. The idea of an indicator should be introduced as a means of distinguishing between the three possibilities, using litmus as the indicator.

Equipment

Apparatus

Eye protection

Watch glasses, 1 per sample (note 1)

White tiles, 1 per sample (note 1)

Red and blue litmus paper, 3 pieces of each per working group

Chemicals

Access to small amounts of common everyday substances such as (note 2)

fizzy drinks

tap water

de-ionised/distilled water

toothpaste

shampoo

soap

vinegar

lemon juice

Health, safety and technical notes

Read our standard health and safety guidance

Wear eye protection.

Provide small amounts of the samples on watch glasses. The watch glasses can be placed on a white tile marked with the name of the substance (use a waterproof marker). The samples can be arranged around the room so that the students visit each in turn. If any solid sample is used, moisten it with a little de-ionised water.

Check hazard labels on any household substances provided. If this activitiy is set as homework, especially on substances not listed above, pupils should be warned that there are many hazardous chemicals in the home. It is recommended that if chemicals such as bleach, drain clear, or scale remover are to be investigated that this is done by the teacher in school. Thick rubber gloves should be worn if planning to do this due to their hazards.