Investigating “Green Powder”

The task in hand was to work out what the green powder really is, by running a series of experiments on it. Before the experiments began, we first had to look the container for any hazard signs, this one displayed the harmful sign, and thus meaning it should not be induced. After this, we came up with some questions, to which the answer would help us work out what the green liquid. These questions were:

Will it dissolve in water?

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Does it dissolve in sulfuric acid (H4SO2)?

What happens when the powder is heated over a Bunsen flame?

With these questions in hand we set out to find the answer to each of them and thus find out what the green powder is.

With it dissolve in water?

Equipment

1 test tube

1 spatula

1 test tube rack

Diagram

Method

First of all we took a test tube and filled it to 1/3 with water after which we added a spatula full of the green powder, and left in a test tube rack to see if it would dissolve.

Results

Although it had looked like it had dissolved at first, after time it turns out it had not. (This effect is called suspension, when the molecules of the powder mix between the water making it seem as though it has dissolve, although time reveals that it hasn’t) therefore the powder doesn’t dissolve in water.

Will the powder dissolve in sulfuric acid?

Equipment

1 spatula

1 test tube

1 test tube rack

1 pair of goggles

Diagram

Method

First of all we put on our goggles because sulfuric acid if corrosive and would be extremely harmful if it got in our eyes. Then we put a spatula of the green powder into your test tube as before. Then we put the test tube into the test tube rack after gently pouring the sulfuric acid into the test tube. After this we observed the results.

Results

After we added the sulfuric acid, it was obvious that there had been a reaction because the solution had begun to fizz and change colour. After the solution had settled (though it was still fizzing slightly) it was obvious that the two substances had reacted together to make a blue liquid. From experience, we were able to identify the solution as copper sulfate, thus telling us that if the sulfur and some, if not all of the oxygen came from the sulfuric acid then the green powder must contains copper to some level.

What happens when you heat the powder over a Bunsen flame?

Equipment

1 test tube

1 spatula

1 pair of tongs

1 Bunsen burner

1 pair of goggles

Diagram

Method

First we put on our goggle incase something went wrong and the green powder shot off out of the test tube. Then we put a spatula of the green powder in a test tube. The test tube was then held with the tongs (to protect our fingers) and was then held in and out of the flame repeatedly (to slow the heating process and thus reduce the chance of accidents occurring) until we were satisfied that the heat had caused a change to occur.

Results

As the powder heated, it started to change colour from green to black. Also the particles of the powder started to vibrate violently, this is due to the heat going into the powder. But the cause of the powder turning black was either the loss of, or addition of a gas. Though from whichever scenario, the result of the reaction seems to be copper oxide (CuO).

To investigate this further we repeated the sulfuric acid experiment to see if a reaction still occurred with the CuO, to which the results were the same as in the same experiment with the green powder.

Another thing that we noticed in the sulfuric acid experiment was that some sort of gas was being given off, so our next experiment was to find the answer to the question.

What gas is being given of from the copper sulfate solution?

Equipment

2 test tubes

1 bung with fitted glass tube

1 spatula

1 pair of goggles

Diagram

Method

Like in the sulfuric acid experiment, first we put on our goggles, and then we put a spatula of the green powder into one of the test tubes, and put a small amount of lemon juice into the other test tube. Then we held the two test tubes in position, near each other. Then we poured the sulfuric acid into the test tube with the green powder, as before, but this time we put the bung with the glass tube into the end, and put the other end of the glass into the test tube with the lemon juice, and observed the results.

Results

The gas from the reaction traveled through the tube and into the test tube of lemon juice, which collected the gas. The gas then turned the lemon water misty, which means that the gas must be CO2 or carbon dioxide. From this, we can work out that if the carbon didn’t come from the sulfuric acid (H4SO2), so therefore it must have come from the green powder.

Conclusion

From all the experiments carried out on the green powder, we were able to establish that the green powder contains copper, because it reacts with the sulfuric acid to make copper sulfate. Also we were able to establish that the green powder also contains carbon, because, when the powder reacts with the sulfuric acid, it gives of carbon dioxide. And finally, although it cannot be certain, the solution may contain oxygen, because in the heating experiment the powder may be giving off carbon dioxide, therefore leaving copper oxide. If all this is true, then from the results, the green powder must be Copper Carbonate (CuCO3).