# Why did roasting of copper(II) sulfate pentahydrate hurt my nose?

I want to use copper(II) sulfate as rocket propellant additive in hope that it will alter the flame colour. Because water is not welcome in rocket fuel, I decided to dehydrate the crystals.

First I tried stainless steel mess tin, but that produced some smoke warning me that it's reacting. So I switched to aluminium mess tin, that one didn't smoke.

But still some fumes, presumably steam was produced. I continued roasting. Almost at the end, I noticed that my nose hurts in the inside a little.

I suppose copper sulfate has got in there. Do you think I risked badly, or is it just weak irritation? How can I avoid it next time, apart of using fumehood?

• You probably just want to do it a lot slower, like in an oven at about 120 °C overnight or something like it. – Martin - マーチン Oct 6 '14 at 14:11
• I'm guessing that by roasting it, some of the sulfate converted to some sulfur gases? – Gimelist Oct 6 '14 at 14:28
• I find this question somewhat disturbing with regards to the complete lack of safety awareness during the planning stage of the experiment. – tschoppi Oct 6 '14 at 21:21
• @tschoppi You wouldn't believe how right you are. I had nasty accident with the same compound later. However now I'm afraid to ask why it happened, because I think I'll just get more comments suggesting how stupid am I. – Tomáš Zato - Reinstate Monica Oct 7 '14 at 15:31
• @TomášZato Well, ask your questions anyway. You will surely get a snarky comment or two, but just to be clear: Behind that unpleasant-looking comment is a real human being that is genuinely concerned for another one. Please just learn from the mistakes you make, so you don't do the same error twice :) – tschoppi Oct 7 '14 at 19:49

Roasting of copper(II) sulfate at elevated temperatures generates sulfur trioxide, which would hurt your nose.

\begin{align} \ce{\underset{\text{(blue)}}{\ce{CuSO4.5H2O}} &->[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][100\ \mathrm{^\circ C}] CuSO4.H2O + 4H2O}\\[6pt] \ce{CuSO4.H2O &->[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][\gt\ 200\ \mathrm{^\circ C}] \underset{\text{(white)}}{\ce{CuSO4}} + H2O}\\[6pt] \ce{CuSO4 &->[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][] CuO + SO3} \end{align}

For me, tschoppi really nails the right response to this question.

Before you handle any chemical you are unfamiliar with, you should first read AND UNDERSTAND all facets of the MSDS (SDS) for that chemical. You need to understand the hazard potential, risk mitigation steps, emergency response strategies and disposal management of all chemicals you are handling.

If you have the capacity to legally obtain chemicals such as copper sulfate pentahydrate, you should also be able to obtain the MSDS (SDS). Google searching will also provide you with this information.

Now, with regards to $\ce{CuSO4.5H2O}$, it has a GHS signal word DANGER, with the following key safety statements:

Hazard Statements

• Toxic if swallowed.
• Causes skin irritation.
• Causes serious eye irritation.
• Very toxic to aquatic life.

Precautionary Statements

• Wash skin thoroughly after handling.
• Do not eat, drink or smoke when using this product.
• Avoid release to the environment.
• Wear protective gloves/ eye protection/ face protection.

Response Statements

• IF SWALLOWED: Immediately call a POISON CENTER or doctor/physician.
• IF ON SKIN: Wash with plenty of soap and water.
• IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
• If skin irritation occurs: Get medical advice/ attention.
• If eye irritation persists: Get medical advice/ attention.
• Take off contaminated clothing and wash before reuse.

Additionally, it advises to wear correct respiratory protection (P2 or N99) and avoid breathing vapours mist or gas.

Given this information, it is unsurprising that you experienced an irritation-type reaction to breathing the vapours. So, how to avoid this next time? Read and understand the MSDS prior to use. Employ the correct protective equipment. Carry out the procedure in a suitably ventilated area, with active ventilation. This could be outside with a strong fan pushing vapours away. If you are unsure about how to handle this chemical correctly, forgo the pretty colours on your rocket.

• Thank you for broad safety info. I was however aware of copper sulfate irritation danger in general. I was wearing safety glasses to avoid risk of eye irritation. I just didn't expect that any gas will form during the process. Your post literally does not contain any information I didn't know. Instead of acting negatively while mentoring me, you could've explained what exactly happened. – Tomáš Zato - Reinstate Monica Oct 7 '14 at 15:25

I want to use copper(II) sulfate as rocket propellant additive in hope that it will alter the flame colour.

It likely won't. AFAIK, common colored flame mixture using copper is copper benzoate/potassium perchlorate mix (pale blue trace), but using it involves known risks of explosive combustion in case of improper handling. In case you are interested in colored light compositions, you need specifically designed compositions, and most of them are not health-friendly.

I suppose copper sulfate has got in there. Do you think I risked badly, or is it just weak irritation? How can I avoid it next time, apart of using fumehood?**

There is no much risks here, though next time stick to ceramics. Copper salts are prone to hydrolysis, so I believe you smelled some sulfuric acid vapors. Not pleasant, but not deadly. In comparison, copper chloride would hydrolyze completely, producing much hydrochloric acid vapors, and that would be much worse.