Review for your upcoming AP exam for AP Chemistry
In this post, we begin your preparation for the AP exam by going over a question that we have as part of our free AP practice questions for a topic Omninox offers. The current exams provide an explanation after a user takes the exam, but these posts (and all future posts) will focus on having a more in depth look at the questions and explaining it in further depth for those that need the extra help. In that case, let’s get started!
For the AP Chemistry Exam, a sample question from the “Sample Questions” is shown below:
Which of the following functional groups is/are capable of hydrogen bonding?
II. Carboxylic Acid
The answer choices are:
- II and III only
- II only
- I and II only
- I only
The correct answer to this question in this case is choice 3, I and II only. Now how do we go about solving this question?
Step 1: In order to answer this question, one needs to know what hydrogen bonding actually is. It is defined as one of the attractive forces between a hydrogen atom attached to an electronegatively charged atom (usually oxygen, fluorine, chlorine) in a molecule and another electronegative atom of another molecule. Basically, the hydrogen from one molecule is attracted to an oxygen from another molecule. This is possible due to the difference in electronegativities between the hydrogen and more negative atom, like oxygen for example. You need hydrogen to achieve hydrogen bonding!
Step 2: You must know what the standard organic chemical groups look like. Each of the presented chemical groups have a set structure and format to them which reveal which ones are capable of hydrogen bonding.
An alcohol functional group looks like:
A carboxylic acid functional group looks like:
A keytone functional group looks like:
Looking at all three functional groups, you can see that carboxylic acids and alcohols are the only ones that have a hydrogen atom that is capable of hydrogen bonding. The keytone has a double bonded oxygen attached to an alkane chain. There is no free hydrogen atom present that’s available for hydrogen bonding. That’s why only carboxylic acids and alcohols are the only viable options in this question and are the answer.
Phew, hopefully that review was both insightful and helpful. Look for more of these question reviews for different subjects in the future as a way to help you in preparing for your AP Chemistry exam!
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