Characteristic Reactions of Acids
Purpose:
To treat several different metals with acid and to identify any gas produced. To treat a carbonate
and a bicarbonate with acid and to identify any gas produced. To study an acid-base
neutralization reaction.
Background:
Acids ionize in aqueous solution to produce hydrogen ions (H+). The strength of an acid depends
on the degree to which it ionizes. Strong acids ionize almost completely, while weak acids
ionize to a lesser degree. Bases dissociate in aqueous solution to produce hydroxide ions (OH-).
(Ammonia gas, NH3, actually ionizes in aqueous solution to produce a weak base.) The
properties of acids and bases depend on the presence of the free H+ or OH- as the predominant
ion in a solution.
In this experiment we will observe the following:
1. Reactions of acids with metals. The single replacement can be represented by the
general equation:
metal + acid  metallic ion + hydrogen gas
M(s) + 2H+(aq)  M2+(aq) + H2(g)
2. Reaction of an acid with a carbonate and bicarbonate. The double replacement
reaction can be represented by the general equation:
carbonate + acid  carbon dioxide + water
CO32-(aq) + 2H+(aq)  CO2(g) + H2O(l)
3. Neutralization reaction. Acids neutralize bases (and vice versa). For example, when
HCl combines with NaOH, the net reaction is
H+ + OH-  H2O
Equipment:
Safety goggles
Test tube rack
Forceps
Test tube holder
Test tubes
10 mL Graduated cylinder
Scoopula
Spot plate
Chemicals:
6 M hydrochloric acid, HCl
1 M hydrochloric acid, HCl
iron staples
magnesium ribbon
calcium carbonate, CaCO3
6 M acetic acid, CH3COOH
Wood splints
copper strips
zinc strips
sodium bicarbonate, NaHCO3
Procedure:
WEAR YOUR SAFETY GLASSES THROUGHOUT THE EXPERIMENT!!
As you perform the experiment, record your observations on the report sheet.
1. Place a piece of each metal in a spot on a spot plate.
2. Place several drops of 6M hydrochloric acid in a sample of each metal. CAUTION: HCl is
corrosive. Note the degree of reactivity for each sample. (VF - very fast, F - fast, M - moderate,
S - slow, VS - very slow, or NVR.)
3. Repeat steps 1 through 2 using 6 M acetic acid instead of hydrochloric acid.
4. Obtain a larger piece of magnesium and place it in a medium test tube. Add about 5 mL of
1M hydrochloric acid to the metal. Check for the production of hydrogen gas by collecting the
gas in a medium inverted test tube and testing it with a burning wood splint.
5. Clean out the test tubes and spot plate. Pick out any pieces of un-reacted metal with the
forceps and place them on a paper towel. Dispose in the trash.
6. Place 3 mL of 1 M hydrochloric acid in each of two test tubes. Add a small sample of sodium
bicarbonate to one and a small sample of calcium carbonate to the other. Check for the gas being
produced by holding a burning wood splint at the top of the test tube. If the flame goes out,
carbon dioxide is the gas most probably being produced.
7. Flush the solutions in the drain.
8. Rinse all of the test tubes with tap water and place them in the plastic bin.