Classify the following as elements, compounds and mixtures: Chlorine gas, potassium chloride, bronze, aluminium, diamond, carbon monoxide, Iron filings, iron sulphide, soda water, air, water, gallium, iodine, tincture of iodine, silicon, sugar, table salt, slaked lime, magnesium ribbon, lead nitrate.
Answers
Element : An element is a pure substance. The representative particles for an element are all atoms of a single element.
An element can be located on a periodic table.
For example, hydrogen H, sodium Na etc.
Compound : A compound is also a pure substance but it is a combination of 2 or more elements. The representative particles for a compound are molecules.
They contain 2 or more elements combined in a fixed ratio.
For example, water H₂O. Here 2 elements H and O are combined in 2:1 ratio.
Mixture : A mixture is a combination of 2 or more substances which are not combined in a definite ratio. A Mixture has variable composition and they do not have definite representative particles.
For example, alloys are made by mixing different metals.
A salt solution is a mixture of water and NaCl.
Components of a mixture can be separated by physical processes like evaporation, filtration etc.
Based on the above discussion we can categorize the given compound as follows.
1) Chlorine gas ( Cl₂) = Element
Because it contains only 1 type of element
2) Potassium chloride ( KCl) = Compound
3) Bronze = Mixture
Its an alloy of copper and tin.
4) Aluminium (Al) = Element
Contains single element
5) Diamond (C) = Element
6) Carbon monoxide (CO) = Compound
Combination of C and O
7) Iron filings (Fe) = Element
8) Iron sulphide (FeS) = Compound
9) Soda water = Mixture
In soda water, the gas is mixed with water
10) Air = Mixture
Air is a mixture of various gases like N₂, O₂, CO₂ etc.
11) Water (H₂O) = Compound
12) Gallium (Ga) = Element
13) Iodine (I) = Element
14) Tincture of iodine = Mixture
Tincture is made by dissolving iodine in alcohol and water along with some other substances like NaI or KI
15) Silicon (Si)= Element
16) Sugar ( C₁₂H₂₂O₁₁) = Compound
17) Table salt (NaCl) = Compound
18) Slaked lime [Ca(OH)₂] = Compound
19) Magnesium ribbon ( Mg) = Element
20) Lead nitrate [ Pb(NO₃)₂] = Compound