Help with Lab Work: Acids and Bases Safety

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In summary: An oil or grease will dissolve in water if it is in a solution, but will not dissolve in soap because soap is a surfactant.Soap is a surfactant that helps to create an oil in water emulsion.An oil or grease will dissolve in water if it is in a solution, but will not dissolve in soap because soap is a surfactant.Soap is a surfactant that helps to create an oil in water emulsion.
  • #1
MermaidWonders
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Which of the following will burn your skin if you get it on you?
a. concentrated sulfuric acid
b. concentrated nitric acid
c. concentrated potassium hydroxide
d. concentrated hydrochloric acidMy first instinct was that all of them would since they are either concentrated acids or bases. I then tried to answer this question by consulting the MSDS for all of the above, but then all of them had "Causes severe skin burns and eye damage". So now, I am confused. Should we be considering the strength of the acids and base?
 
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  • #2
Hi MermaidWonders,

Isn't it the same thing?
That is, yes, in their concentrated forms they all cause chemical burns.
In a weak form they only irritate the skin.
 
  • #3
Klaas van Aarsen said:
Hi MermaidWonders,

Isn't it the same thing?
That is, yes, in their concentrated forms they all cause chemical burns.
In a weak form they only irritate the skin.

Sorry, I didn't clarify. "Strength" as in whether the acid/base is strong or weak. So should I consult the table of relative strengths of acids and bases, or is it already obvious to say that all of them would burn the skin?
 
  • #4
MermaidWonders said:
Sorry, I didn't clarify. "Strength" as in whether the acid/base is strong or weak. So should I consult the table of relative strengths of acids and bases, or is it already obvious to say that all of them would burn the skin?

An acid or base must both be strong and concentrated to burn the skin.
This is the case for all 4 of them.
I think we can assume that if we call it an acid or a base that it will burn the skin in a sufficiently concentrated form though.
Even vinegar will burn the skin if sufficiently concentrated.
Still, if it's hardly an acid at all (even water is considered to be both acidic and basic), it will obviously not burn the skin.
 
  • #5
Klaas van Aarsen said:
An acid or base must both be strong and concentrated to burn the skin.
This is the case for all 4 of them.
I think we can assume that if we call it an acid or a base that it will burn the skin in a sufficiently concentrated form though.
Even vinegar will burn the skin if sufficiently concentrated.
Still, if it's hardly an acid at all (even water is considered to be both acidic and basic), it will obviously not burn the skin.

Ah, makes sense now. Thank you so much! :)
 
  • #6
Hi, sorry if this is a really dumb question, but since soaps have both a polar and a non-polar component to them, does it mean that they can actually dissolve all substances (polar and non-polar)?
 
  • #7
I would not use the word dissolve; solubilize is a better term. The soap will help create an oil in water emulsion wherein the oil is dispersed into small particles. This property of soap is why it is a member of the more general class of materials called surfactants. The basic feature of a surfactant is that one end of the molecule is hydrophobic such as a long hydrocarbon chain while the other end is hydrophilic such as a sulfonate group; depending on the balance of strength between the 2 ends of the molecule you get surfactants that can form oil in water emulsions and others that can form water in oil emulsions.
 
  • #8
DavidCampen said:
I would not use the word dissolve; solubilize is a better term. The soap will help create an oil in water emulsion wherein the oil is dispersed into small particles. This property of soap is why it is a member of the more general class of materials called surfactants. The basic feature of a surfactant is that one end of the molecule is hydrophobic such as a long hydrocarbon chain while the other end is hydrophilic such as a sulfonate group; depending on the balance of strength between the 2 ends of the molecule you get surfactants that can form oil in water emulsions and others that can form water in oil emulsions.

So they essentially solubilize everything?
 
  • #9
You can manage to emulsify most any hydrocarbon liquid in water or water in a hydrocarbon and solubilize is an extreme case of emulsification where the emusified particles are so small that they don't scatter light. It can be hard to make a stable emulsion and even harder to make one where the particles are so small that they don't scatter light. Making stable emulsions is an art.
 
  • #10
Hey, just another question pertaining to the same lab from last week... since soap can make oil/grease soluble in water, why is hexane immiscible in soap solution?
 
  • #11
I went from you saying solution to me saying emulsion. A surfactant is not going to make a true solution, it will make an emulsion and if you work really hard you might be able to make the emulsion particles so small that the liquid will appear clear.

I would expect that you could make a hexane in water emulsion by selecting the proper surfactants. There are thousands of different surfactants you can purchase, selecting the correct combination for a particular emulsion is the art. A place where I worked, they made a paraffin in water emulsion; perhaps hexane would be more difficult.

You can also use a co-solvent to bring immiscible substances into solution. Colognes contain water and essential oils etc. that would not normally be miscible; you get a clear solution because 70% or more is ethanol. If you start diluting the cologne with more water it will become cloudy as the organics drop out of solution. Another example is the alcoholic drink called absinthe, it is a clear green colored liquid containing essential oils along with the alcohol but as you add it to water it becomes cloudy as the essential oils drop out of solution (forming an emulsion).
 
  • #12
DavidCampen said:
I went from you saying solution to me saying emulsion. A surfactant is not going to make a true solution, it will make an emulsion and if you work really hard you might be able to make the emulsion particles so small that the liquid will appear clear.

I would expect that you could make a hexane in water emulsion by selecting the proper surfactants. There are thousands of different surfactants you can purchase, selecting the correct combination for a particular emulsion is the art. A place where I worked, they made a paraffin in water emulsion; perhaps hexane would be more difficult.

You can also use a co-solvent to bring immiscible substances into solution. Colognes contain water and essential oils etc. that would not normally be miscible; you get a clear solution because 70% or more is ethanol. If you start diluting the cologne with more water it will become cloudy as the organics drop out of solution. Another example is the alcoholic drink called absinthe, it is a clear green colored liquid containing essential oils along with the alcohol but as you add it to water it becomes cloudy as the essential oils drop out of solution (forming an emulsion).

So is soap just not the appropriate surfactant to make a hexane in water emulsion? Also, is it true that we can essentially make almost any emulsion by choosing the right surfactants?
 
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  • #13
To the first question: yes, that would be my guess.

To the second question: that is saying more than should be inferred. Making emulsions is an art, I don't know of any way to compute a result.
 
  • #14
DavidCampen said:
To the first question: yes, that would be my guess.

To the second question: that is saying more than should be inferred. Making emulsions is an art, I don't know of any way to compute a result.

Alrighty, thank you so much!
 

FAQ: Help with Lab Work: Acids and Bases Safety

1. What are the common safety precautions when working with acids and bases in the lab?

When working with acids and bases in the lab, it is important to wear appropriate personal protective equipment (PPE) such as gloves, goggles, and a lab coat. It is also important to work in a well-ventilated area and to handle these chemicals with care to avoid spills or splashes. Additionally, it is recommended to have a neutralizing agent, such as baking soda, on hand in case of accidents.

2. How should I handle and store acids and bases in the lab?

Acids and bases should be handled with caution and care. When transferring these chemicals, use proper techniques such as using a dropper or pouring slowly to avoid spills. It is also important to label all containers properly and to store them in a designated area away from other chemicals. Acids and bases should also be stored separately from each other to avoid any potential reactions.

3. What should I do if I accidentally spill acid or base on my skin?

If you accidentally spill acid or base on your skin, immediately rinse the affected area with large amounts of water for at least 15 minutes. Remove any contaminated clothing and seek medical attention if necessary. It is important to always have a first aid kit and safety shower nearby when working with these chemicals.

4. Can I dispose of acids and bases down the drain?

No, acids and bases should never be disposed of down the drain as they can be harmful to the environment and can potentially damage plumbing systems. It is important to follow proper disposal procedures, which may include neutralizing the chemicals with a base or acid, before disposing of them in designated waste containers.

5. What are some common acids and bases used in the lab?

Some common acids used in the lab include hydrochloric acid, sulfuric acid, and nitric acid. Common bases used in the lab include sodium hydroxide, potassium hydroxide, and ammonium hydroxide. It is important to familiarize yourself with the properties and safety precautions of each specific acid and base before using them in the lab.

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