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I'm handling 0.12N of sulfuric acid for a science experiment that I am carrying out for a school project. I hear about all these terrible effects if it's ingested, inhaled, or gets in contact in skin. But how dangerous is it?

My safety equipment that I'm using currently are a pair of polyvinyl gloves, goggles, long sleeve shirt, apron, jeans, and closed toe shoes. However, I do not have a respirator and wondering if I should get one.

Would it be safe to handle this without a respirator? I will not be spraying the sulfuric acid directly in the air. However, I will be adding approximately 0.5mL of the 0.12N sulfuric acid into 500mL of water, putting it in a spray bottle, and be watering some plants with it. Will it still be dangerous even spraying a low concentration in the air?

Would the 0.12N concentration still be enough to cause chemical burns on my skin? To what extent and severity? Also, just to confirm, it is safe to add drops of the acid to water, but not vice versa? I would really appreciate the advice that you can provide me.

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    $\begingroup$ You don't need a respirator since sulfuric acid you are using is 300 times less concentrated than the concentrated sulfuric acid which is much more hazardous. You shouldn't be harmed if a little got on your skin if you wash it off quickly. You may want to have a solution of baking soda (5g/100mL) to put on any spins that get on your cloths. The solution that you will be making (pH of 4, this is the acidity of pickles) is even less hazardous and small amounts could probably be inhaled without any problems (but of course, I wouldn't want to do so). $\endgroup$
    – LDC3
    Nov 13, 2014 at 3:39
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    $\begingroup$ This is not a question about personal medical advice but lab safety practice and as such I consider it perfectly on topic for this site. $\endgroup$
    – tschoppi
    Nov 13, 2014 at 14:27
  • $\begingroup$ This is a good example of the principle of dose response: If something is harmful, then a bigger dose is more harmful and a smaller dose is less harmful. The alternative view (not borne out by the science) is that if something is harmful at all, it must be harmful in any quantity. $\endgroup$
    – iad22agp
    Nov 14, 2014 at 18:52

3 Answers 3

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0.12 Normal = 0.06 Molar.

For comparision, concentrated sulphuric acid is 18 Molar.

So the 0.12 N sulphuric acid is over 99% water.

Would it be safe to handle this without a respirator?

Yes, the vapor pressure of sulphuric acid is low, and it has already been diluted with considerable water, so there is no need for a respirator.

My safety equipment that I'm using currently are a pair of polyvinyl gloves, goggles, long sleeve shirt, apron, jeans, and closed toe shoes.

Goggles are the most important safety equipment. An eye wash station and shower are also standard lab safety equipment.

The gloves are good because liquids will not pass through them. Ordinary clothing isn't really helpful because if you did spill something on that part of your body, the substance would absorb into the cloth and you would just be delayed in washing that part of your body by having to take off the clothes.

Would the 0.12N concentration still be enough to cause chemical burns on my skin? To what extent and severity?

Pronged contact may cause some damage, but nothing comparable to the concentrated acid. If you spill some on yourself, stay calm, and wash with soap and water. If you spill on your clothes, take the wet clothes off first, then wash with soap and water.

Also, just to confirm, it is safe to add drops of the acid to water, but not vice versa?

This is always a good rule to keep in mind. 0.12N is dilute enough that little heat will be released from 0.5mL, but just follow the rule.

However, I will be adding approximately 0.5mL of the 0.12N sulfuric acid into 500mL of water, putting it in a spray bottle, and be watering some plants with it. Will it still be dangerous even spraying a low concentration in the air?

Now you are diluting another 1000 fold. The solution will be around pH 4, similar to some rain water. I would still want you to wear goggles and not spray in the direction of anyone.

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That dilute of $\ce{H2SO4}$ won't remotely burn your skin. You can wear goggles just in case you spray it in your face for some reason.

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Q1) For the first question, we can calculate the molarity of the sulphuric acid.(Molarity of acid × volume of acid = molarity of the dilute acid × the volume of water) 0.12N × 0.5ml = molarity of dilute acid × 500ml Molarity of dilute acid = 0.12N × 0.5ml / 500ml = 0.00012N Thus, you can see that the molarity of the acid is quite low, meaning the ph value is nearly at 4 or 5. I can say that is not necessary to wear the respirator but remember to prepare something base or alkaline for cases like the acid start to burn the gloves or your skin.

Q2) Yes. You must add the drop of acid into the water and not vice versa. It is because if you instantly add water to acid, the solution will form an exothermic reaction and release a lot of heat, causing the acid to boil and splatter itself everywhere.

However, if you add drops of acid to water. The heat produce is not enough to cause the solution to boil. Hence, it is must more safer.

I hope that it will help you on experiment.

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