(a) What is an amalgam?
(h) State at least one method of preventing rusting
2. Define mctal with an example,
o Write two properties of metal.
3. Write one of the reaction for each of the following characteristics
ta) Formation of precipitate
(b) Evolution of heat
Answers
Answer:
a) An amalgam is an alloy of mercury with another metal. It may be a liquid, a soft paste or a solid, depending upon the proportion of mercury. ... Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore.
h) Galvanising is a method of rust prevention. The iron or steel object is coated in a thin layer of zinc. This stops oxygen and water reaching the metal underneath - but the zinc also acts as a sacrificial metal . Zinc is more reactive than iron, so it oxidises in preference to the iron object.
2. The definition of metal is any of the elements with a positive electrical charge, typically with a shiny surface and a good conductor of heat. An example of metal is gold.
o Properties of Metals
●Luster: Metals are shiny when cut, scratched, or polished.
●Malleability: Metals are strong but malleable, which means that they can be easily bent or shaped. ...
●Conductivity: Metals are excellent conductors of electricity and heat.
3) a) 3.Formation of precipitate:
The action of Barium Chloride on sodium sulphate.
BaCl2(aq)+Na2SO4(aq)→BaSO4(s)+2KNaCl(aq)
b) reactants → products + energy.
exothermic reaction