Im not sure where to factor in the two longer compounds for this problem.
"Rank the given compounds based ontheir relative acidities"
HF
H2C--CH2
NH3
CH4
HC---CCH3
This is the order i thought it was, but this isnt right apparently...
(--- means triple bond, -- means double bond)
You didn't post the order you thought was correct. And the problem doesn't say increasing acidity or decreasing acidity.
From least acid to most acid.
NH3
CH4
ethylene
methyl acetylene
HF
H atoms on double and triple bonded carbon are acidic, triple bonds always moreso than double bonded C.
okay thanks but that was wrong actually
Sorry about that. I mixed up the NH3 and CH4
As a series, they go across the periodic table like this.
CH4 NH3 H2O HF with HF being the most acid and CH4 the least acid. Actually, I typed it that way the first time but the computer didn't post it and when I redid it I screwed up.
To rank the given compounds based on their relative acidities, you need to consider their molecular structure and the factors that affect acidity. Acidic compounds tend to have an easily removable proton (H+) from their molecular structure.
Here are the steps to determine the relative acidities:
Step 1: Identify the acidic proton in each compound.
In each compound, identify if there is a proton (H+) that can be removed easily. Remember that acidic protons are typically attached to electronegative elements (elements with high electron-attracting ability) or located near electron-withdrawing groups.
Step 2: Compare the stability of the resulting conjugate bases.
After removing the acidic proton from each compound, compare the stability of the generated conjugate bases. More stable conjugate bases indicate stronger acids.
Step 3: Arrange the compounds based on their acidities.
Based on the stability of the conjugate bases, arrange the compounds in order from strongest acid to weakest acid.
Now, let's follow these steps for your given compounds:
HF:
The acidic proton is the hydrogen (H+) attached to the electronegative fluorine (F) atom. This compound is a strong acid because the fluoride ion (F-) is a very stable conjugate base.
H2C--CH2:
In this compound, there are no acidic protons to remove. Therefore, it is not acidic and should be placed at the bottom of the acidity ranking.
NH3:
The ammonia molecule (NH3) has one acidic proton attached to the nitrogen (N) atom. When the proton is removed, it forms the ammonium ion (NH4+), which is a stable conjugate base. Thus, NH3 is a weak acid.
CH4:
Methane (CH4) does not have any acidic protons, so it is not acidic and should be placed at the bottom of the acidity ranking.
HC---CCH3:
The terminal proton in this compound attached to the carbon atom is acidic. When removed, it forms a propyne anion, which is a relatively stable conjugate base. Therefore, HC---CCH3 is a weak acid.
Based on the above analysis, the correct order of the given compounds based on their relative acidities is as follows:
1. HF (strong acid)
2. HC---CCH3 (weak acid)
3. NH3 (weak acid)
4. CH4 (not acidic)
5. H2C--CH2 (not acidic)