Question

I'm following a protocol from some old literature (1962), and I want to make sure I'm being safe. It asks you to dissolve some salts in 150 mL water + 25 mL concentrated HCl, then evaporate to dryness at 100 °C. So the question is whether the acid is dilute enough that this is safe to do in a benchtop drying oven (i.e., not inside a fume hood). I imagine back in 1962, you might have done this drying on steam bath inside a fume hood, but I haven't seen a steam bath around for ages. If this is not safe, please suggest how it could be done safely (I do have a fume hood, but the oven won't fit inside).

Telling me to check with my PI or safety officer isn't going to be helpful in this case.

Answer 1

Dissolving salts with concentrated HCl and evaporating should be done in a fume hood due to the release of corrosive HCl gas. If the oven does not fit in a fume hood.

Step-by-step explanation:

The process of dissolving salts in water combined with concentrated HCl and then evaporating the solution to dryness can be hazardous and should not be done outside of a fume hood.

The hazard arises from the potential release of HCl gas upon heating, which is corrosive and can cause respiratory irritation. A safer alternative would be to evaporate the solution in an environment with adequate ventilation, such as a fume hood.

In cases where the oven does not fit inside the available fume hood, alternative methods such as a rotary evaporator (if available) or setting up a safe and effective local exhaust system for the benchtop drying oven, would be recommended.

Additionally, a steam bath can also be used as a heat source as it provides a more controlled and gentle method of heating, reducing the risk of violent reactions and minimizing the release of HCl gas.