I know you are, so what am I?
What type of material is this?
a) a pure substance which is a compound ex: water H2Odefinite chem composition
b) a pure substance which is an element ex: diamond C , gold Au, silver Ag
c) a solution of compounds ex: salt in water NaCl + H2Odefinite chem composition
d) a solution of elements ex: bronze(alloy): Cu(s) + S(s)
e) a mechanical mixture of compounds ex: copper sulphate + alcohol
CuSO4 + C2H5OH
f) a mechanical mixture of elements ex: iron nails + zinc pellets Fe(s) + Zn(s)
1) At room temperature, a material is a homogeneous green liquid that has a definite
composition. Although it is separable into simpler substances by means of a
chemical reaction, it is not separable by dissolving, filtration, chromatography or any
other physical change. The material can be best described as:
definite composition: compound or element, has a chemical formula
cannot be a solution (separated by evaporation)
cannot be a mechanical mixture: homogeneous/same throughout
cannot be an element: can be separated by chemical means
Ans: pure substance that is a compound
2) At room temperature, a material is a homogeneous purple liquid that has a definite
composition. It is separable into simpler substances by means of a chemical reaction
as well as by dissolving, filtration, chromatography or any other physical change. The
material can be best described as:
cannot be mechanical: homogeneous
physical + chemical separations
Therefore it is a solution of compounds (KMnO4 + H2O)
3) A beaker containing a colorless liquid. After the liquid was evaporated, there was no
residue in the beaker. The material can be best described as:
Cannot be a solution (solid dissolved in a liquid)
It can be a pure liquid compound such as water, alcohol
Could it be mercury or bromine? No, mercury is shiny liquid, bromine is brown liq.
4) A beaker containing a colorless liquid. After the liquid was evaporated, there was a
white residue in the beaker. The material can be best described as:
residue: solute(solid) dissolved in the solvent(liquid)
liquid that is a solution of compounds ex: NaCl (salt) dissolved in water
5) A material is a homogeneous brown gas that has a definite composition. Although it is
separable into simpler substances by means of a chemical reaction, it is not
separable by dissolving, chromatography, or any other physical change. The
material can be best described as:
definite composition: compound or element has a chemical formula
can be separated chemically: compound that is a gas at room temperature
A pure substance that is a compound
Ex: NO2 (smog)
6) A copper penny is dipped into a heated solution of tin. The penny becomes silver. After
depositing this penny on a hot plate, it changes into a gold colour. What type of
material is this gold penny?
copper silver  gold
+ Sn
Cu + Sn = brass
alloy: solution of metals (Cu + Sn)
Ans: solution of elements (alloy)
7) A heterogeneous black material is in a sealed erlenmeyer flask. A magnet atracts
some of this material, with the remaining black powder left on the bottom of the flask.
The material can be best described as:
magnet: only attracts iron(Fe)
Heterogeneous mixture: 2 black powders in flask (Fe and C)
Answer: mechanical mixture of elements Ex: iron filings with coal dust