AAMC 8 solution

[chiddler]

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I stared at this for way too long :|

Which of the following statements is consistent with the incorrect conclusion that HCl is ionic?

B. A 1 M solution freezes below 0 degrees C.
*C. A 1 M solution conducts electricity

I know that the passage says ionics conduct electricity! But why oh why is B wrong?!

 

[MedPR]

I stared at this for way too long :|

Which of the following statements is consistent with the incorrect conclusion that HCl is ionic?

B. A 1 M solution freezes below 0 degrees C.
*C. A 1 M solution conducts electricity

I know that the passage says ionics conduct electricity! But why oh why is B wrong?!

I think the info to why B is wrong is somewhere in the passage.

 

[chiddler]

I think the info to why B is wrong is somewhere in the passage.

it's not!!

all the text minus table which just lists electronegativities.

 

[MedPR]

Sorry, I meant that B is wrong because C is a better answer because C is explicitly stated in the passage. I'll take a look at the passage in a minute and see if I find anything else though.

 

[chiddler]

you're right about the answer being in the passage.

but come on. it's..

just

not fair!!

 

[MzAries]

I understand why this was the correct answer being that it was in the passage but this is not a correct statement in general right?? Certainly aqueous HCl CAN conduct electricity right?? It will dissociate into H+ and Cl- so I don't see why it can't.... That's how you measure conductivity no??

 

[MedPR]

I understand why this was the correct answer being that it was in the passage but this is not a correct statement in general right?? Certainly aqueous HCl CAN conduct electricity right?? It will dissociate into H+ and Cl- so I don't see why it can't.... That's how you measure conductivity no??

Re-read the question; It correctly says that HCl can conduct electricity, which is the reason why you might think it is an ionic compound.

 

[MzAries]

Re-read the question; It correctly says that HCl can conduct electricity, which is the reason why you might think it is an ionic compound.

Right, so the question stem is stating that the statement HCl is an ionic compound is INCORRECT, therefore it is NOT an ionic compound in reality. Therefore the answer that is consistent with the incorrect statement would be that it CAN conduct electricity, suggesting that in reality it cannot because it is really covalent, not ionic.

I'm confused by this because I always thought that while HCl is covalant, it does dissociate in water and become ionic and therefore can conduct electricity.

 

[chiddler]

Right, so the question stem is stating that the statement HCl is an ionic compound is INCORRECT, therefore it is NOT an ionic compound in reality. Therefore the answer that is consistent with the incorrect statement would be that it CAN conduct electricity, suggesting that in reality it cannot because it is really covalent, not ionic.

I'm confused by this because I always thought that while HCl is covalant, it does dissociate in water and become ionic and therefore can conduct electricity.

i don't think it "becomes ionic". rather, it ionizes in solution which is different from actually being in an ionic bond.

yes it should conduct electricity in reality as well.

 

[MedPR]

Right, so the question stem is stating that the statement HCl is an ionic compound is INCORRECT, therefore it is NOT an ionic compound in reality. Therefore the answer that is consistent with the incorrect statement would be that it CAN conduct electricity, suggesting that in reality it cannot because it is really covalent, not ionic.

I'm confused by this because I always thought that while HCl is covalant, it does dissociate in water and become ionic and therefore can conduct electricity.

Let me reword the question so it will make more sense to you.

The question says this "Which of the following properties of HCl would lead you to believe that HCl is ionic even though it is covalent?" Answer: HCl solution conducts electricity.

 

[ridethecliche]

Covalent things can lead to FP depression as well.

They just don't break into two ions. Remember the formula has the i for the number of particles it breaks into.

NaCl would give 2
Glucose would give 1

They'd still cause FP depression.

 

[MzAries]

Let me reword the question so it will make more sense to you.

The question says this "Which of the following properties of HCl would lead you to believe that HCl is ionic even though it is covalent?" Answer: HCl solution conducts electricity.

Okay, I see what you're saying now. Tricky tricky! I wasted time on that question because of the stupid wording and would have gotten it wrong it the other choices made any remote sense.