Which of the following molecules has a double bond?
1. NO3- 4. H2
2. C2H4 5. C12
3. SO2 6. None of the previous answers
I got that three of these molecules have a double bond (NO3-, SO2, and C2H4), but the answer is one. I am thinking that maybe the professor wants C2H4 because it is the "clearest cut" double bond?
Yes and No. The answer is 1 and that is C2H4. The so-called "double bond" in NO3^- and SO2 are not real double bonds although we draw double bonds with the Lewis dot structure. Remember that there are resonance forms so these double bonds are only figments of our imagination. In real life they are somewhere between a single bond and double bond and all of the bonds are equal.
You are correct that there are three molecules among the options given that have a double bond: NO3-, SO2, and C2H4. However, if the question asks for only one molecule with a double bond, then the correct answer is C2H4, also known as ethene. This is because C2H4 has a carbon-carbon double bond, which is a clear and specific example of a double bond.
To determine which of the given molecules has a double bond, we can look at the Lewis structures or molecular formulas of each molecule.
1. NO3-: The Lewis structure of NO3- shows that it has a resonance structure with one double bond and two single bonds, represented as O=N-O. So it has a double bond.
2. C2H4: The molecular formula C2H4 indicates that this molecule is ethene (ethylene). In the Lewis structure of C2H4, there is a double bond between the two carbon atoms. Therefore, C2H4 has a double bond.
3. SO2: The Lewis structure of SO2 reveals that it has a double bond between the sulfur atom and one of the oxygen atoms. So it has a double bond.
4. H2: H2 is the molecular formula for hydrogen gas. It consists of two hydrogen atoms bonded together by a single bond. It does not have a double bond.
5. C12: C12 is a molecular formula that does not correspond to any specific molecule. Therefore, we cannot determine if it has a double bond or not.
6. None of the previous answers: Since three of the given molecules (NO3-, C2H4, and SO2) have a double bond, we cannot select this option as the correct answer.
Based on the analysis, the correct answer is C2H4. It is the only molecule out of the given options that definitely has a double bond. The other options either have a double bond in some resonance structures (NO3-) or have an ambiguous molecular formula (C12).