Chem Lab, do ions combine in definite ratios.

Topics: Chemistry, Ratio, Chemical reaction Pages: 5 (820 words) Published: May 19, 2003
LAB 3.Ø.Ø: do ions combine in definite ratios

PURPOSE

The purpose of this investigation is to determine whether ions combine in definite ratios or not. To observe, and create a table of the different ions.

QUESTION

If copper (II) sulfate when mixed with sodium carbonate at different quantities combine to form ions in definite ratios.

HYPOTHESIS / PREDICTION

I believe that the ions will combine in definite ratios due to the fact that the valance electrons will not be changing throughout any chemicals; consequently the ions must combine in definite ratios.

EXPERIMENTAL DESIGN

A technique is performed in which copper (II) sulfate and sodium carbonate are placed together in various test tubes, with various quantities of each chemical and a chemical reaction should happen. The time for the two chemicals to completely react is about five ? ten minutes. The temperatures of the solutions, the quantities of the solutions are all controlled variables. The chemicals are known to form a precipitate.

MATERIALS

-Safety glasses-10 ml copper (II0 sulfate solution

-Seven test tubes-10 ml sodium carbonate solution

-1 test tube rack- Tap water

-Masking Tape

-Two Eye Droppers

PROCEDURE

1.Placed goggles on face.

2.Numbered the test tubes from 1 ? 5 and place in test tube rack.

3.Washed the test tubes with tap water.

4.Using the eyedropper, added the appropriate number of copper (II) sulfate to the numbered test tube.

5.Using the second eyedropper, added the appropriate number of sodium carbonate to the numbered test tubes.

6.Swirled test tubes gently to mix the contents.

7.Allowed the precipitate to settle for 7 minutes.

8.Recorded observations.

OBSERVATIONS

Table 1.1

Test Tube #(Column 1)

Copper (II) Sulfate Drops (column2)

Sodium Carbonate Drops (Column 3)

General Observations- ColourPrecipitate (column4)

119Light BlueLittle

237Medium BlueMedium

355Dark BlueLarge

473Medium BlueMedium

591Light BlueLittle

Double Displacement: CuSO4 (aq) + NaCO3 (aq) à CuCo3(s) + NaSO4 (aq)

ANALYSIS

1.2

Test Tube #: 1 2 3 4 5

Copper (II) Sulfate Drops: 1 3 5 7 9

Sodium Carbonate Drops: 9 7 5 3 1

Ratio of Cu 2+ ions to CO3 2-ions:1:9 3:7 5:5 7:3 9:1

1.The reaction that occurred in the experiment was a chemical reaction, double displacement-precipitate reaction. The Copper reacted with the carbonate and form the precipitate, while the Sodium and Sulfate was the ?clear? part in the test tube.

CuSO4 (aq) + NaCO3 (aq) à CuCo3(s) + NaSO4 (aq)

2.Refer to table 1.2

3.The test tube that contains the most precipitate is #3. This one has the most because of the ratio of Cu to CO3 ions (1:1); therefore the Copper can react equally with the carbonate and the Sodium with the Sulfate. I can conclude then that the close the ratio is the more precipitate will be present.

4.Test tubes #1 and #5 contain the least precipitate because the ratios are the largest, (1:9 , 9:1). Both test tubes produced the same amount of precipitate though. Since the ratios are large that means that one chemical will only have a small amount to react with the other chemical. I can establish that opposite ratios will have the same amount of precipitate.

5.This evidence suggests that ions combine in definite proportions because whenever a large amount of the copper (II) sulfate was added to a smaller amount of the sodium carbonate a small amount of precipitate was produced. Also whenever a small amount of copper (II) sulfate was added to a larger amount of sodium carbonate, still a small amount of precipitate was formed. Therefore ?

Furthermore ions do combine in definite ratios because of the valance electrons. Each chemical has a certain amount of valence electrons, so when another chemical comes to form a molecular bond it must occupy the remaining area of the shell to become stable. No matter what the chemical will always have the same amount of valence...
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