Question 13

[M.C.]

Hi,
Shouldn't C be the answer to this question?
Thank you

[matthew]

I think this would be a classic example where the stem provides enough clues to take this problem home. They tell us that very little product is formed. We know that strong acids have a high Ka meaning a lot of ions are being dissociated.

From this rule, weak acids must dissociate very little, or in other terms, form few products. Writing out the K constant with products over reactants, we can see that the reason that Ka values are so big is that there is a large dissociation.

So just understanding why Ka constants are in terms of writing the eqn, and applying this to the clue "very few products (i.e. ions) formed" we have slipped through the other wrong answer choices which do not provide an correct answer to our problem.


Hope this helps. I found that if I go to the problems I missed and look for words that I am not sure about and reference them, I can go directly to my weakness. With time, seeing another problem like this will lower your anxiety b/c you a)know what the problem is asking (b/c you have base knowledge) and b) you are able to solve it b/c you can see the connection)


For example, in BS section, terms like energy might be thinking about mitochondria, or prokaryotes, thinking no organelles, or ADH, water conservation. Kind of like "connect the dots"

[admin]

If the proton is there, no matter where it comes from, it will be, in part, attracted to the delta negative oxygen in -OH. Thus C cannot be true. The problem is that there are not enough protons created and the reason is that HF is on your list of weak acids (CHM 6.1).

[jellywing_2058]

The explanation never mentions that the reaction does not occur; it simply says that only a small amount of product forms. The reason for this is that the acid used (HF) is weaker than HCl, meaning that it is less reactive and that signifies that the yield will be smaller.

[mohsinalam5969]

the answer (A) is absolutely right because if we carefully read the question we will understand that the question is "only a small amount of product is obtained" it doesnt mean that only 1 product is obtained and 2nd is not obtained.....

the reason why i thought that this answer is correct lies in the concept of not only that HF is weak acid but also in the difference of the bond energies of HF & HCl.
further the anhydrous hydrogen halides are all colourless gases at STP except for hydrogen fluoride, which boils at 19 °C due to strong hydrogen bonding.
and all this is due to that HF is a weak acid