A student adds 1.00x10^-8 moles HCl to a liter of soln. The resulting soln will be acid, basic, neutral, or impossible to determine?
I believe that it is impossible to determine, because it does specify that the temperature was at 25*C.
Which of the species act as a Lewis acid: CH3CH2N or NO2?
I think NO2, because one of its oxygen is missing an electron.
Lactic acid partially dissociates, Ka=1.4x10^-4, to form hydronium ions and conjugate base. Determine kb for this base.
kb=10^-14/ (1.4x10^-4)= 7.1x10^-11
Is that how I am supposed to do this?
Thanks for the help!
A student adds 1.00x10^-8 moles HCl to a liter of soln. The resulting soln will be acid, basic, neutral, or impossible to determine?
A bad question BECAUSE there are no limits on it. Of course it can be determined. We can measure it with a pH meter, for example. Or we can calculate it. Or from common sense, if we have some water that is neutral, and we add some HCl to it (no matter how few molecules of HCl we add), then the resulting solution MUST be acid. Not very acid, perhaps, but acid.
I believe that it is impossible to determine, because it does specify that the temperature was at 25*C.
Which of the species act as a Lewis acid: CH3CH2N or NO2?
I think NO2, because one of its oxygen is missing an electron.
I still think something is wrong with the N in the first formula so I'm skipping this one.
Lactic acid partially dissociates, Ka=1.4x10^-4, to form hydronium ions and conjugate base. Determine kb for this base.
kb=10^-14/ (1.4x10^-4)= 7.1x10^-11
Is that how I am supposed to do this?
Yes, the procedure is correct although I didn't check the math. Kb = Kw/Ka.
I read Bob Pursley's answers to your later post of this same question. For number 1, his answer is better than mine because the problem just says solution and we don't know the pH of the solution. My answer is correct because I put enough disclaimers on it (such as neutral solution) etc but the problem clearly states solution and not neutral solution.
how many grams are produced from 1.5L of 6M HCl
For the first question, to determine whether the resulting solution is acid, basic, neutral, or impossible to determine, we need to consider the concentration of hydronium ions in the solution.
The equation for the dissociation of HCl is:
HCl → H+ + Cl-
Given that the student adds 1.00x10^-8 moles of HCl to 1 liter of solution, we can calculate the concentration of hydronium ions ([H+]).
[H+] = 1.00x10^-8 M
Since the concentration of hydronium ions is not specified to exceed or fall below the concentration thresholds for acidic or basic solutions, it is impossible to determine the nature of the resulting solution (acidic, basic, or neutral) without additional information.
For the second question, determining which species acts as a Lewis acid, we need to understand that Lewis acids accept an electron pair.
In CH3CH2N and NO2, nitrogen (N) has a lone pair of electrons that can be shared. However, in CH3CH2N, the nitrogen atom is already sharing its lone pair with the surrounding atoms, making it unlikely to accept any additional electron pairs.
On the other hand, NO2 has an electron-deficient oxygen atom as one of its constituents. It can accept a lone pair of electrons, making it a Lewis acid.
So, NO2 acts as a Lewis acid.
For the third question, you are almost there. To determine the Kb (base dissociation constant), you need to use the Kw (water autoionization constant) and the Ka (acid dissociation constant).
Kw = [H+][OH-] = 1.0x10^-14 (at 25°C, standard temperature)
Ka = [H+][A-]/[HA]
Since Ka and Kw are related as Kw = Ka * Kb, we can rearrange this formula to find Kb:
Kb = Kw / Ka = 1.0x10^-14 / (1.4x10^-4) = 7.1x10^-11
So, your calculation for Kb is correct.
You're welcome! If you have any more questions, feel free to ask.