Page 98 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

Reaction of metals with acids
Where do metals
You have already studied the reaction of zinc with
come from?
dilute hydrochloric acid. Write down the products
Metals are isolated from
formed as a result of this reaction.
naturally occurring materials
containing metallic compounds.
Repeat the experiment by adding metals like zinc, Such materials found in the

aluminium, iron and magnesium in different test tubes earth’s crust are known as
minerals. Metals are separated
containing dilute hydrochloric acid. What do you
from them by chemical
observe?
processes. Gold is a metal which
• Which of these metals reacted with the acid? exists in free state. Aluminium is
the most abundant metal on the
earth’s crust followed by iron and
• Which of these metals reacted most vigorously?
calcium.
• Is there any metal which did not react with the acid?

• Which gas is liberated during these reactions? How Metals in human
would you detect it? Try to find out. body too!
• Is there any difference in the vigour of the reaction Though needed only in small
of the metals with the acid? quantities, the presence of
certain metallic minerals is
Let's write down the balanced chemical equation of
essential for the normal
some of these reactions. functioning of the human body
and for health and nutrition.
Zinc + Hydrochloric acid Zinc chloride + Hydrogen Haemoglobin, the compound

Zn + 2HCl ZnCl + H which gives red color to blood,
2 2
contains iron. Calcium is
Mg + 2HCl
essential for the growth of teeth
Fe + 2HCl and bones. Salts of sodium and
2Al + 6HCl potassium are essential for the

When metals like aluminium, zinc, magnesium and proper functioning of cells. Traces
of metals like zinc, copper and
iron react with acids, hydrogen gas is formed along with
selenium are essential for
the salt of the metal.
maintaining the health of a
You have studied that acids are present in lemon and person.
buttermilk. Now you can guess why a stainless steel
knife is preferred to an iron knife to cut lemons and
also why it is not wise to store buttermilk in aluminium
See 'Acidum Lohangalum'
vessels. in School Resources in
IT@ School Edubuntu

Basic Science VIII 97