|GOAL: This experiment explores some of the reactivity of ionic compounds. You will observe a variety of double displacement reactions. Upon completion of this experiment, you should be able to predict the products of a double displacement reaction.|
|Double displacement reactions are of the type:
AB + CD à AD + BC
In the reactions you will study, each of the compounds will form ions in solution, then the ions will recombine to form new compounds, or remain in solution. In today's experiment you win perform the reaction, observe the results, then test known compounds and design further experiments using these known compounds to test your hypotheses about what has occurred. If you see no visible signs of reaction, such as a temperature change, a precipitate being formed, or a gas being released, it may be that the compounds have simply dissolved in solution without recombining. If you feel this is the case, simply write "no reaction", however you must justify this conclusion.
An example of a double displacement reaction is the following:
NaCl + AgNO3 à NaNO3 + AgCl
When solutions of the two reactants are combined, a white precipitate
is formed. This is definite evidence that a reaction has occurred.
In this reaction, sodium chloride dissolves in solution to form sodium
ions Na+ and chloride ions (Cl-) Silver nitrate dissolves to give
silver ions (Ag+) plus nitrate ions (NO3- ). These ions recombine
to form the products as shown in the reaction. How can you tell which
product or if both are the white precipitate? One way would be to
take a small amount of sodium nitrate (NaNO3) and see if it dissolves
in water. If it does, you can rule it out as the product that precipitated.
Likewise you could see if silver chloride dissolves in water. If you
did these experiments you would find that NaNO3 does indeed dissolve
in water whereas AgCl does not. You would conclude that the white
precipitate formed was AgCl.
NaOH + HCl à NaCl + H20
The only evidence of a reaction having occurred is a temperature change. The reaction vessel feels warm to the touch. This heat is released when water forms from the hydroxide ion (OH-) and the proton (H+).
In today's experiment you will combine reactants, notice any evidence of a reaction (precipitate, color change, temperature change, etc.) and determine what reaction has occurred, if any, by observing other combinations of reagents and testing known compounds from the laboratory.
2.) Write the ions for the compounds listed in the previous question.