Copper citrate

Synthesize copper citrate and explore its properties!

Difficulty:
Danger:
Duration:
2 days
Copper citrate

Reagents

Safety

  • Put on protective gloves and eyewear.
  • Remove protective gloves before lighting the splint (step 6).
  • Conduct the experiment on the plastic tray.
  • Keep a bowl of water nearby while working with fire.
  • Keep flammable materials and hair away from flame.
  • Observe safety precautions when working with boiling water.
General safety rules
  • Do not allow chemicals to come into contact with the eyes or mouth.
  • Keep young children, animals and those not wearing eye protection away from the experimental area.
  • Store this experimental set out of reach of children under 12 years of age.
  • Clean all equipment after use.
  • Make sure that all containers are fully closed and properly stored after use.
  • Ensure that all empty containers are disposed of properly.
  • Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
  • Do not replace foodstuffs in original container. Dispose of immediately.
General first aid information
  • In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
  • If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
  • In case of inhalation: Remove person to fresh air.
  • In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
  • In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
  • In case of injury always seek medical advice.
Advice for supervising adults
  • The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
  • This experimental set is for use only by children over 12 years.
  • Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
  • The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
  • The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
  • Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

FAQ and troubleshooting

The copper(II) sulfate didn't dissolve in 10 seconds. What should I do?

If there are relatively large crystals in the beaker, stir for about 10 more seconds. If the remaining crystals are relatively small, they should dissolve later in the experiment.

I can't get the sodium citrate out of the bottle.

Use a wooden stick from the set to loosen the sodium citrate in the bottle. This should help break up any lumps and allow you to measure the sodium citrate as intended.

The solution in the flask after filtering is slightly blue. Is everything okay?

Yes, this is okay. The copper(II) sulfate solution is blue, and when filtered, the sediment remains on the filter while the solution drains into the flask. Make sure that the filter isn’t torn (this will let sediment into the flask). If this happens, you’ll have to change the filter.

The filter is torn. What should I do?

First, don't worry! If there is sediment on the filter, then carefully put it on the tray and leave to dry. If the sediment has gotten into the flask, then pour the solution into the beaker and rinse the flask with water to wash off the residue. Repeat the process with a new filter and continue the experiment.

It’s filtering so slowly! Can I use a wooden stick to stir the sediment and speed up the process?

No, you shouldn't do that. You might tear the filter.

There’s a small amount of sediment remaining in the beaker.

In this case, pour more water into the beaker, carefully swirl it, and quickly transfer the mixture to the filter. If necessary, repeat this step several times.

The sediment is still sticky; what should I do?

Try letting it sit in a dry place for at least 4 more hours or until it dries out. Continue the experiment.

I added sodium citrate and stirred the solution, but there’s no sediment.

Something definitely went wrong. Luckily, the set should contain enough reagents for you to repeat the experiment from the very beginning once more. Be sure to dissolve the copper(II) sulfate in boiling water.

Step-by-step instructions

Make a copper sulfate CuSO4 solution. CuSO4 doesn't really fancy dissolving in cold water, but will do just fine in hot water.

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Add some sodium citrate. Both copper sulfate and sodium citrate are soluble in water, but they can combine to form copper citrate, which is not.

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Filter out the solid copper citrate.

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Rinse the precipitate once more and let it dry.

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The light blue powder you end up with still contains a lot of water. If you heat it carefully, the water will evaporate, and the crystals will turn dark blue.

copper-v3_copper-citrate_en-astm963_iks-s-05

One cool thing about dry copper citrate is that it decomposes quite spectacularly if you set it on fire.

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Disposal

Dispose of the reagents and solid waste together with household garbage. Pour solutions down the sink and wash with an excess of water.