Answer:
See explanation and images attached
Explanation:
a) In the mechanism for the acid catalysed esterification of propanoic acid using ethanol, we can see that the first step is the protonation of the acid followed by nucleophillic attack of the alcohol. Loss of water and consequent deprotonation regenerates the acid catalyst. We can see the fate of the 18O labelled ethanol in the mechanism shown.
b) In the second mechanism, an unnamed ester is hydrolysed using an acid catalyst. The attack of the acid and subsequent nucleophillic attack of water labelled with 18O leads to the incorporation of this 18O into the product acid as shown in the mechanism attached to this answer.
Argon is the third most common gas found in the air we breathe. The air we breathe has approximately 78% nitrogen and 21 % oxygen. The third more abundant gas in the air we breathe is Argon. It is available in a very small quantity in the air that we breathe.
The percentage of the gas argon is about 0.9% in the air
that we breathe. There are several other gases also present in the air that we
breathe, but they are found mostly in negligible amounts.
Answer:
Aspirin was purified in the lab by recrystallizing the crude aspirin. The melting point of the purified aspirin is expected to be lower than the melting point of crude aspirin.
Explanation:
The presence of impurities in a sample lowers the melting point of the impure substance. Hence the melting point of an impure substance is always less than the melting point of the corresponding pure substance.
Bearing this in mind, the statement "Aspirin was purified in the lab by recrystallizing the crude aspirin. The melting point of the purified aspirin is expected to be lower than the melting point of crude aspirin." is found to be false since impure substances tend to have a slightly lower melting point than the pure substance, and a broader melting temperature range.
I believe the correct answer from the choices listed above is option C. The ratio of Al3+ ions to S2- ions in a neutral compound would be 2:3. When it is a neutral compound the chemical formula would be Al2S3. As you can see in every 2 ions of Al you need 3 ions of S to maintain neutrality. Hope this answers the question.
