Lab- 5B

Lab- 5B

Objective:

1. To observe a variety of chemical reaction

2. To interpret and explain observations with balanced chemical equations

                3. To classify each reaction as one of the four main types

Reaction 1:

       

Adjust a burner flame to high heat.

Using crucible tongs, hold a 6cm length of bore copper wire in the hottest part of the flame for a few minutes

Changes during: it starts to change color

Changes after: it turns to black

Equation- Cu+O2 à 2CuO (synthesis)

Reaction 2:

       

Clean an iron nail with a piece of steel wool so the surface of the nail is shiny

Place the nail in a test tube and add copper (II) sulfate solution so that one half of the nail is covered

After approximately 15 mins, remove the nail and note any changes in both the nail and the solution

Changes during: liquid starts to turn green and bubbles all over the nail

Changes after: liquid becomes green

Equation- 3CuSO4 +2Fe à Fe2 (SO4) + 3Cu (single replacement)

Reaction 3:

Put some solid copper (II) sulfate pentahydrate in a test tube so that it is 1/3 full

Using the test tube clamp to hold test tube, heat the test tube, moving it back and forth gently over burner flame

        Continue until there’s no further change is observed

Changes during: smoke appear

Changes after: It turns white

Equation- CuSO4 .5H2Oà CuSO4 +5H2O (decomposition)

Reaction 4:

Allow the test tube contents from reaction 3 to cool

Use medicine dropper to add 2 or 3 drops of water

       

Changes during: change color, heated

Changes after: turns black to blue

Equation- CuSO4 +5H2Oà CuSO4 .5H2O (synthesis)

Reaction 5:

Allow the test tube one quarter with calcium chloride solution. Fill a second test tube one quarter full with sodium carbonate solution

Pour the calcium chloride solution into the test tube containing sodium carbonate solution

       

Changes during: smoke it’s a fast reaction, turn white after added together

Changes after: white solid and becomes milky

Equation- CaCl2 (aq) +Na2CO3 (aq)à 2NaCl2aq) +CaCO3(s) (double replacement)

Reaction 6:

Place a piece of mossy zinc in a test tube

Add hydrochloric acid solution to the test tube until the mossy zinc is completely covered

       

Changes during: zinc starts to get less, bumbles starts to appear

Changes after: zinc disappears, liquid turns a little white

Equation- 2HCl+Znà ZnCl2+H2 (single replacement)

Reaction 6:

Half fill as a test tube with hydrogen peroxide solution.

Add a small amount of manganese (IV) oxide

Test the evolved by placing a glowing splint into the mouth of the test tube

       

Changes during: Bubbles occurs

Changes after: the blowing splints burning again

Equation- 2H2Oà(MnO2) 2H2O+ O2 (decomposition)