Background: The ions of many common metals impart a characteristic color to a flame. Often these ions are used commercially in fireworks and color-producing "logs." The characteristic color can be used to identify the presence of an unknown ion. In this lab you will investigate the colors produced by ions from groups 1 and 2. The data will be used to identify unknown ions.

Safety: Wear chemical splash goggles, gloves, and an apron. Hold the burning splint over your ceramic plate. Use caution when igniting the Bunsen burner. Be sure to wet all splints before placing them in the nonhazardous waste container.

Disposal: Return unused wooden splints to your teacher. Place wet used splints in the nonhazardous waste container.

Materials:

2 cobalt glass plates Bunsen Burner Flint lighter

Ceramic plate 10 splints: 1-Li, 2-Na, 2-K, 1-Ba, 1-Ca, 1-Cu, 1-Sr, 1-Na/K 2 splints: unknown1, unknown 2

Procedure: Note: record all observed colors in the data table.

1. Ignite your Bunsen burner and adjust the flame to produce a nonluminous flame.
2. Place your ceramic plate next to the burner.
3. Place the lithium splint in the flame and observe the color.
4. Repeat step 3 with Na, K, Ba, Ca, Cu, and Sr.
5. Observe a second burning potassium splint through two pieces of cobalt glass.
6. Observe a second burning sodium splint through two pieces of cobalt glass.
7. Observe the sodium/potassium splint flame through two pieces of cobalt glass.
8. Observe the flames generated by the two unknowns. Using the data recorded in your Data Table, identify the metal ion(s) present in the flame.

Objective: To determine the percentage of hydration for a hydrate.

Safety: Wear chemical splash goggles, gloves, and an apron. Tie back long hair. Use caution in handling the crucible and cover. Transport the crucible and cover on a clean ceramic plate.

Disposal: The magnesium sulfate may be placed in the nonhazardous waste container or flushed down the drain.

Materials

crucible and cover Bunsen Burner triangle pipe and stem iron ring electronic or centigram balance

Ceramic plate crucible tongs ring stand 4g magnesium sulfate

Procedure

1. Heat the crucuble and cover for five minutes.
2. To avoid transfer of mass from your fingers, always handle the crucible and cover with crucible tongs. Place the crucible and cover on a clean ceramic plate. Cover the crucible when it is not being heated.
3. When the crucible and cover have cooled, determine the mass of the crucible and cover and record it in the Data Table.
4. Add approximately 4g of hydrated magnesium sulfate to the crucible. Determine the mass of the crucible, cover, and contents and record it in the Data Table.
5. Place the crucible in the triangle pipe stem. Put the cover on, leaving it slightly ajar. Heat the crucible assembly gently for five minutes. If a crackling sound is heard, remove from heat. After five minutes increase the heat gradually until maximum heat is applied.
6. Continue to heat the assembly for seven to eight more minutes.
7. Remove the crucible and place it on the ceramic plate.
8. After teh crucible has cooled, use your tongs to transfer the crucible to the balance and determine its mass. Record the mass in the Data Table.
9. Reheat the crucible for another ten minutes [cover ajar] and repeat steps 7 and 8.
10. If the difference between mass measurements is greater than 0.01 g, repeat steps 6-8 until the mass measurements differ by 0.01 g or less. Record this mass in the Data Table as the constant mass.
11. Dispose of the magnesium sulfate as directed by your instructor.

Analysis
1. Calculate the mass of the hydrated MgSO₄ using data from the first two entries in the Data Table. Record the result in the Calculations Table.
2. Calculate the mass of anhydrous MgSO₄ using data from the first and fifth entries in the Data Table. Record the result in the Calculations Table.
3. Using the data from the first two entries in the Calculations Table, determine the mass of water lost from the hydrate and record it.
4. Determine the percentage of water in the hydrate from them mass of the water lost and the mass of the hydrate. Record this percentage.
5. Your instructor will provide you with the accepted value. Using that value, calculate the error and percentage error.

Objective: To investigate double replacement reactions and write complete equations for each precipitate-forming reaction.

Safety: Wear chemical splash goggles, gloves, and an apron. Many of the ions used are toxic. Practice strict hygiene.

Disposal: Follow your instructor's directions regarding disposal.

Materials

96-well plate 6 prefilled, labeled pipets containing the following: 0.1 M solutions: silver nitrate, barium nitrate cobalt(II) nitrate, copper(II) nitrate, and lead(II) nitrate

8 prefilled, labeled pipets containing the following: 0.1 M solutions:  sodium iodide, sodium carbonate, sodium oxalate,potassium ferricyanide, sodium bicarbonate, sodium phosphate, sodium sulfate, and sodium silicate pipet rack

Procedure
1. Obtain the 96-well plate and arrange the plate so that the long axis is horizontal.
2. Obtain the two sets of prefilled pipets and place them in your pipet rack.  Do not mix up the two sets.
3. Place 2 drops of silver nitrate in wells A1-A8.
4. Place 2 drops of barium nitrate in wells B1-B8.
5. Similarly, place 2 drops each of the following solutions in wells 1-8 of their respective rows: C, cobalt(II) nitrate; D, copper(II) nitrate; E, iron(III) nitrate; F, lead(II) nitrate.
6. To all of the wells in vertical column 1, add 2 drops of sodium iodide.  Observe the reaction and record your observations in the Data Table.
7. To all of the wells in vertical column 2, add 2 drops of sodium carbonate. Observe the reation and record your observations in the Data Table.
8. To each of the remaining vertical columns, add 2 drops respectively of each of the following solutions: column 3, sodium oxalate; column 4, potassium ferricyanide; column 5, sodium bicarbonate; column 6, sodium phosphate; column 7, sodium silicate;column 8, sodium sulfate. Observe each reaction and record your observations in the Data Table.

Analysis
Write a complete balanced equation for each reaction that produced a precipitate.