The Chemical Rainbow-Acids and Bases
->What is the
use of sanitary cleaner like Harpic?
To clean
toilet/floor stains etc.
->Haven’t you
been advised by your elders not to touch this liquid? Why?
Yes, because it harms the skin if it comes in contact with
our skin.
Acids are substances which produce hydrogen ions when
dissolved in water. ·
Hydrochloric acid (HCl) and Sulphuric acid (H2SO4) are strong acids.
natural acids such as
formic acid(HCOOH) and acetic acid (CH3COOH) are weak acids.
-> What will
happen when base is dissolved in water?
It will produce hydroxide
ions .
->How you can
identify if a substance is acid or base as it is hazardous to taste all
chemicals?
By use of indicators.
Type of Indicator
|
|
Example
|
Natural indicator
|
Naturally occurring
substances which act as indicators
|
Litmus, turmeric, red cabbage
and china rose .
|
Synthetic indicators
|
They are produced in the
laboratory using chemicals
|
Phenolphthalein, methyl orange colour indicators
|
Olfactory indicators
|
|
Garlic
|
Litmus: ®
is one of the earliest known indicators and it is a natural dye obtained from
lichens
®
solution turns red when added to acid solution.
®
solution turns blue when added to basic solution.
-> When acids dissolves in water which ions are
formed.
Hydrogen ions
-> Give one example of strong base?
Sodium
hydroxide/ potassium hydroxide/ calcium hydroxide.
->What happens
when red litmus paper is dissolved in base?
Red litmus paper turns blue.
->What are
indicators?
Indicators are substances that changes their
properties according to acidic or basic environment.
-> Give
examples of natural indicators.
litmus, china
rose, turmeric
-> What happens when you try to wash a turmeric stain on your
clothes with soap?
The stain turns
red in colour.
-> When
turmeric paper strip is dipped in the shampoo solution , the colour of turmeric paper strip changes to red,
It indicates that shampoo solution is basic in
nature.
-> When turmeric paper strip is dipped in the cold drink , the
colour of turmeric paper strip does not chang.
Cold drink is
acidic in nature.
-> Give any
two examples of natural indicators.
Litmus/Turmeric/China rose
-> Name one synthetic indicator?
Phenolphthalein is a colourless synthetic indicator. When it
is added to
an acidic solution,
it remains colourless
a basic solution ,it
turns bright pink.
-> What is the
colour obtained when universal indicator is added to hydrochloric acid?
Bright red
->What is the
colour obtained when universal indicator is added to calcium hydroxide?
Violet
-> What is the
neutralisation reaction?
->When an acid
is mixed with base in a suitable quantity, the resulting solution is neither
acidic nor basic is known as neutralization
reaction.
->What are the
products formed in neutralisation reaction?
Salt and water
->What is the
common name of sodium chloride?
Common salt
->Where do we
use sodium chloride in our daily life?
It is used in food
to add taste and it is also used as preservative.
-> What happen
when you eat spicy or oily food?
we get
acidity/heartburn
-> What you do when you suffer from acidity?
Take medicine to feel better
-> What does
this medicine do to control acidity?
It neutralizes the
excess of acid in our stomach.
-> Which acid
is present in ant’s bite?
Formic acid
-> What should
be added to treat a soil if it’s too basic in nature?
Compost or organic manure should be added to treat the soil
if it’s too basic in nature.