Label each of the following changes as a physical change or chemical change. Give evidence to support your answer.
1 answer:
Answer:
A catalytic converter changes nitrogen dioxide to nitrogen gas and oxygen gas is a chemical change.
Explanation:
Hello.
In this case, since physical changes do not modify the molecular composition and structure of the material undergoing it whereas the chemical change does, for catalytic converters we should know they promote chemical reaction in which the composition is changed; for instance, for the given example, the following chemical reaction is the evidence:
As you can see, nitrogen and oxygen are no longer bonded but separated by themselves, therefore, this is a chemical change.
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Answer:
a. Cyclohexanone
Explanation:
The principle of IR technique is based on the <u>vibration of the bonds</u> by using the energy that is in this region of the electromagnetic spectrum. For each bond, there is <em>a specific energy that generates a specific vibration</em>. In this case, you want to study the vibration that is given in the carbonyl group C=O. Which is located around 1700 cm-1.
Now, we must remember that the <u>lower the wavenumber we will have less energy</u>. So, what we should look for in these molecules, is a carbonyl group in which less energy is needed to vibrate since we look for the molecule with a smaller wavenumber.
If we look at the structure of all the molecules we will find that in the last three we have <u>heteroatoms</u> (atoms different to carbon I hydrogen) on the right side of the carbonyl group. These atoms allow the production of <u>resonance structures</u> which makes the molecule more stable. If the molecule is more stable we will need more energy to make it vibrate and therefore greater wavenumbers.
The molecule that fulfills this condition is the <u>cyclohexanone.</u>
See figure 1
I hope it helps!
