Question about OAT Sample Test

[drill-and-fill]

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All chemicals should be handled with care.
However, extra precautions should be taken
when handling

A. sodium chloride.
B. dilute hydrochloric acid.
C. sodium metal.
D. sodium sulfate.
E. calcium carbonate.

The answer is B.

I was gonna pick C because somewhere in the back of my mind I faintly remember Chad saying that sodium metals are very unstable because they don't exist as pure metals in the natural world, but I didn't listen to that faint voice and picked B instead... and got it wrong. 😳

So is the answer is B because what I said above?

 

[Stacker]

Sodium metal is dangerous only if you have liquids laying around or if you swallow it. HCl is caustic to your skin, eyes, or any other epithelium regardless of the presence of water. That's why you wear gloves, coat, and eye gear in the gen chem labs when you're doing the pKa, pH, dilution experiment
Calcium carbonate is baking soda. NaCl - table salt.

 

[drill-and-fill]

So both sodium metals and the acid are dangerous... but why is sodium metal more dangerous?

 

[chem1234]

Sodium metal in extremely reactive with water. If you had a doplet of water fall on pure sodium metal it would create an explosion. HCL is dangerous, being at a high pH it can eat right through your skin, but being diluted makes it less harmful. Hope that helps

 

[Stacker]

This is a lab question. Alkaline metals are only dangerous with liquids. In other words, you have A which is safe by itself but if you have B, then A+B is dangerous. If you only have A (soft alkaline metal), you don't necessarily have to take as serious a precaution as with acids or bases. Although it is best to always wear protective equipment.

But acid is dangerous even in its diluted form because it can get in your eyes and burn through your cornea. You must have eye and clothing protection. Carrying on the example, A (acid) is dangerous even by itself.

 

[ktran17]

I don't understand how dilute acid could be more dangerous than sodium metal.

Sodium metal + water yields is highly exothermic.

To even move sodium metal, wouldn't you need a special case since it can react with water in the air?

 

[Stacker]

I don't understand how dilute acid could be more dangerous than sodium metal.

Sodium metal + water yields is highly exothermic.

To even move sodium metal, wouldn't you need a special case since it can react with water in the air?

http://www.northstarchemical.com/prod_sulfuricacid_prof.htm

1% of strong acid like sulfuric acid has a pH of 1. Your stomach has a
pH of 2. HCl is a strong acid.
1% of weak acid like vinegar is harmless.

 

[ktran17]

Thanks.

Also, would you guys say dilute acid or dilute base is more dangerous?

I vote dilute base, because its not as apparent compared to acid, but still can cause some serious damage.

 

[Stacker]

Sodium metal in extremely reactive with water. If you had a doplet of water fall on pure sodium metal it would create an explosion. HCL is dangerous, being at a high pH it can eat right through your skin, but being diluted makes it less harmful. Hope that helps

False. At least the second part. And HCl is a strong acid so it has a low pH not a high pH.

 

[ktran17]

Sodium metal in extremely reactive with water. If you had a doplet of water fall on pure sodium metal it would create an explosion. HCL is dangerous, being at a high pH it can eat right through your skin, but being diluted makes it less harmful. Hope that helps

Concentrated HCl is dangerous but it's not going to eat away your skin.. I know this from research experience because I deal with highly concentrated sulfuric acid (18M +)

 

[chem1234]

My bad meant to say low ph, I say things backwards all the time, should have checked. Thanks.

 

[chem1234]

Concentrated HCl is dangerous but it's not going to eat away your skin.. I know this from research experience because I deal with highly concentrated sulfuric acid (18M +)

So if you sit your body in a tub of 18M HCL for 24 hours you would have all your skin still attached?? I'm not saying it's so reactive that if 1 drop gets on your hand it will immediately burn a whole through it or something.

Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes. Acute inhalation exposure may cause coughing, hoarseness, inflammation and ulceration of the respiratory tract, chest pain, and pulmonary edema in humans
http://www.epa.gov/ttn/atw/hlthef/hydrochl.html#ref4

HCl is so strong that if it wasn't for the mucous membrane that protects the stomach lining, the acid would digest the stomach

Read more: http://www.livestrong.com/article/419261-role-of-hydrochloric-acid-in-the-stomach/#ixzz21sJEkTsV​

 

[chem1234]

http://www.northstarchemical.com/prod_sulfuricacid_prof.htm

1% of strong acid like sulfuric acid has a pH of 1. Your stomach has a
pH of 2. HCl is a strong acid.
1% of weak acid like vinegar is harmless.

https://www.ada.org/oat/oat_sample_test.pdf

Question number 62, answer is C. sodium metal.

 

[ktran17]

"handling" chemicals is far different from soaking in a bath tube full of acid. Shoot, if you're gonna do that, I won't be surprised if something like citric acid could dissolve your hand.

Haha, i knew it, sodium metal is more dangerous

 

[chem1234]

"handling" chemicals is far different from soaking in a bath tube full of acid. Shoot, if you're gonna do that, I won't be surprised if something like citric acid could dissolve your hand.

Haha, i knew it, sodium metal is more dangerous

Exactly, lol