Lab 8.3 Reactions in Aqueous Solutions

Purpose

To combine solutions containing cations and anions and name the ionic compounds and write the formulas of any new compounds formed that are insoluble.

Introduction

After completing this experiment you should be familiar with the relative solubility of some common salts (ionic compounds). Solutions of ten salts have been prepared. Five of the salts have a common cation, sodium (Na+). The other five salts have the a common anion, nitrate (NO3-). The number of drops of each salt should be kept constant, so that the only difference in mixtures is the cation from the first group and the anion from the second group.

When a salt dissolves in water, the cations and anions dissociate. When combined with another salt solution, the cations and anions may “switch partners” and form a new compound. If this compound is insoluble in water, it will form a precipitate.

Aqueous Salt (NaCl) Solution


 

 

Materials

Procedure

  1. Place a plastic sheet over the attached 5 X 5 grid.
  2. Place 2 drops of silver nitrate on the plastic sheet in each of the squares in the "A" row. (A1, A2, A3, A4, and A5). Place 2 drops of iron (III) nitrate solution in each of the squares in the "B" row (B1, B2, B3, B4, and B5). Repeat for all of the remaining nitrate solutions, assigning each metal ion to a row of its own.

A.     0.1 M silver nitrate (AgNO3)

B.     0.1 M iron (III) nitrate (Fe(NO3)3)

C.     0.1 M zinc nitrate (Zn(NO3)2)

D.     0.1 M copper (II) nitrate (Cu(NO3)2)

E.      0.1 M calcium nitrate (Ca(NO3)2)

  1. Place 2 drops of sodium chloride solution in each of the "1" squares in the first column: A1, B1, C1, D1, and E1. Place 2 drops of sodium hydroxide in each of the "2" squares in the second column: A2, B2, C2, D2, and E2. Repeat for all of the remaining sodium solutions, assigning each anion to a column of its own.

(1)   0.1 M sodium chloride (NaCl)

(2)   0.1 M sodium hydroxide (NaOH)

(3)   0.1 M sodium carbonate (Na2CO3)

(4)   0.1 M sodium sulfate (Na2SO4)

(5)   0.1 M potassium hydrogen phosphate (K2HPO4)

4)      Mix the solutions in each square with a CLEAN toothpick each time.

5)      Note and record observations for the 25 squares. If the box contains a precipitate after adding the two solutions, fill in the corresponding square with the color of the precipitate and note any unusual observations. If there is no evidence of a precipitate, write “none” in the square. A clear, colorless solution indicates that no precipitate is present.

 

 

Data Table

 

If there is a precipitate, record the color. If there isn’t a precipitate, write “none”.

 

 

 

1

2

3

4

5

Anions à

 

Cl-

OH-

CO32-

SO42-

HPO42-

 

Cations

 

 

 

 

 

A

Ag+

 

 

 

 

 

B

Fe3+

 

 

 

 

 

C

Zn2+

 

 

 

 

 

D

Cu2+

 

 

 

 

 

E

Ca2+

 

 

 

 

 

 

 

Data Analysis and Conclusions:

  1. Which combinations of cations and anions might form new salts or ionic compounds that are soluble? How do you know?

 

 

 

 

  1. Write balanced chemical equations for all combinations that produced a precipitate.

Put a plastic sheet over this grid.