Recent content by JJMB

Thanks for the explanation. It makes sense now.

Homework Statement The standard enthalpy of formation for liquid water is -285.8 kJ / mole. Which of the following could be the standard enthalpy of formation for water vapor? A) -480.7 kJ / mole B) -285.8 kJ C) -241.8 kJ / mole D) +224.5 kJ / mole Homework Equations The...

van der Waals forces: These are very weak forces between temporary dipoles. The electrons around a molecule aren't always symmetrical. If at a particular moment, more electrons are around the left side of a molecule than the right, then the left side carries a partial negative charge and the...

The four quantum numbers are used to describe an electron. 1st QN tells you what shell it is in. n = 1,2,3,... 2nd QN tells you what subshell it is in. l = 0,1,2,... 3rd QN specifies an orbital. m_l can be anywhere from -l to positive l, including 0. This is the reasoning behind the 2l + 1...

I think your answer would be correct if only n and l were given. The reason that 2*l + 1 does not apply is because the magnetic quantum number (m_l) is specified. The magnetic quantum number has to do with energy level within a subshell, and if I remember correctly, each orbital is associated...

I worked through it and got 2.65 * 10^-7 M, a bit off from the answer you gave. I assumed standard temperature and pressure, are you given different information in the problem? I started by calculating the mass of 1 L of air at STP, then used % by mass to calculate mass of the NCl3, used that...

People thought I was crazy for it, but puzzles like this were the reason I liked organic chem. I just worked through this one myself now and it took about 10 minutes of drawing possible structures and crossing them out. Hint: Recall that 2 - 2.5 is the normal range for hydrogens bound to a...

The term multiplet isn't specific as far as I know. When you see multiplet, just think 5+ peaks. A specific description, like sextet or heptet, may be used if very high resolution is being used. You generally won't need to know how many peaks are in a multiplet to solve any of the problems you...

Take one of the hydrogens on carbon #2 in the center of a propane molecule for an example. It has 6 neighboring hydrogens that will split the NMR signal. This would give a total of 7 peaks, which could be referred to as a heptet or more commonly a multiplet.

The oversimplified version is this, depending on the substitution of the aromatic ring, you can have a few doublets or triplets so close together than they become a large multiplet that is hard to differentiate unless you have very high resolution.

With that many degrees of unsaturation, the multiplet in that range is almost certainly hydrogens on aromatic ring / rings.

Using Henderson-Hasselbalch, we find that [acetate] / [acetic acid] = 17.37 This ratio also applies to the number of moles of each, so moles acetate / moles acetic acid = 17.37 Rearranging this equation, we find that: moles acetate = moles acetic acid * 17.37 Since the concentration of the...

Use the Henderson-Hasselbalch to first find the ratio of acetate / acetic acid molarity. This is also the ratio of the number of moles of each. The sum of the two molarities should equal 1.0 M. You must find a way to rearrange one equation and plug it into the other. Post back if you need more...

4-methylcyclohexanol contains a hydroxy group. If you are doing anything with IR, the big broak hydroxy group peak around 3200-3500 1/cm is something you should know by heart. 4-methylcyclohexene, being an alkene, would contain a C=C peak which wouldn't be found in the alcohol. Just consult...

p-nitrophenol and o-nitrophenol would be more acidic than m-nitrophenol. p and o-nitrophenol would be approximately the same acidity. Tip: Try drawing out the resonance structures for each conjugate base to understand. Best of luck, -JJMB Edit: The isomers which have the most stable...