Laboratory 02

1
Laboratory 02 The Discovery of Chemical Change
Through the Chemistry of Copper
2
Objectives

• Observe chemical changes through a series of
  chemical
• reactions.
• Learn simple mass and volume measuring
  techniques.
• Understand and use the law of conservation mass.
• Learn the proper techniques for the handling and
  disposal of
• chemicals

3
Law of conservation mass
Law of conservation of mass is a relation stating
that in a chemical reaction, the mass of the
products equals the mass of the reactants.
http//www.youtube.com/watch?vdExpJAECSL8
4
Copper

• Chemical element with the symbol Cu
• Atomic number 29
• Good electrical and thermal conductor
• Pure copper is soft and malleable
• An exposed surface has a reddish-orange tarnish
• It is used as a conductor of heat and
  electricity,
• a building material, and a constituent of various
  
• metal alloys

5
Copper is an essential element for plants and
animal, through not in metallic form but as
copper (II) ions.
Copper (II) salts contain the copper atoms in an
ionized or charged form and are typically blue to
green in color.
6
The copper cycle
1
5
2
4
3
The cycle of copper reactions to be performed in
this experiment
7
Oxidation A common form of chemical reaction
which is the combining of oxygen with
various elements and compounds. Example The
corrosion of metals is a form of oxidation, rust
on iron for example is iron oxide.
Safety Issue NO2 which is generated during this
experiment is very dangerous. ADD NITRIC ACID IN
A HOOD! Do not walk around the room with a flask
that is evolving brown NO2 gases!
8
Reaction 2 Converting copper nitrate to copper
hydroxide
Cu(NO3)2(aq) 2NaOH(aq) Cu(OH)2(s)
2NaNO3(aq)
9
Reaction 3 Converting copper hydroxide to copper
oxide Cu(OH)2(s) heat
CuO(s) H2O(l)
Dehydration involves the loss of water
10
Most metal oxides are basic oxide and react with
acids to form salts and water metal oxide acid
--gt salt water.
11
Reaction 5 Converting copper sulfate back to
copper metal CuSO4(aq) Zn(s)
ZnSO4(aq) Cu(s)

• Add dilute hydrochloric acid (HCl) and stir to
  dissolve any excess zinc.

Hydrogen gas is highly flammable and will burn in
air at a very wide range of concentrations
between 4 and 75 by volume.

• After this point the solid, pure copper can be
  isolated, dried and weighed.

http//en.wikipedia.org/wiki/Hydrogen
12
Weigh and calculate the mass of copper recovered
and your percent yield using the following
equation
13
Safety Notes
Wear safety glasses at ALL TIMES. You will
be using nitric, sulfuric and hydrochloric acids
as well as sodium hydroxide all are damaging
to skin, clothing and especially your eyes.
Perform Reaction 1 in a fume hood. Toxic NO2 is
produced.
Hydrogen gas is evolved in Reaction 5. Keep
your apparatus away from open flames.
14
Lets enjoy the lab session