All Questions
13
questions
-5
votes
1
answer
113
views
Find the pH of a solution obtained by mixing 100 ml 0.1m Na3PO4 and 100 ml 0.1 M NaH2PO4. Given that H3PO4: [Κα₁ = 10^-4, Κα₂ = 10^-7, К��з = 10^-11] [closed]
So, my query is that since NaH2PO4 is a weak acid, and Na3PO4 is a basic salt, wouldn't they react? Another theory was that since NaH2PO4 is a weak acid and Na3PO4 is a salt of strong acid and NaH2PO4,...
1
vote
0
answers
42
views
Why is it that in a buffer solution the equilibrium concentrations may be assumed to be the initial concentrations? [duplicate]
Considering the Henderson–Hasselbalch equation,
$$\text{pH} = \text{p}K_a + \lg \frac{[\ce{AcO⁻}]} {[\ce{AcOH}]}$$
$$\text{p}K_a = \lg \frac{[\ce{AcO⁻}][\ce{H⁺}]} {[\ce{AcOH}]}$$
Why are the values ...
- 11
0
votes
2
answers
2k
views
How to know if a reaction forms H3O+ ions or OH- ions? [closed]
How would you know when an acid or base is paired with $\ce{H2O}$ that it will form an $\ce{OH-}$ ion or a $\ce{H3O+}$ ion? I just started the acid and base equilibrium unit, and I'm just confused on ...
- 59
1
vote
2
answers
393
views
How can I calculate the amount of HF in aquoues solution of NH4F and an aquoues solution of NH4HF2?
Dissociation of $\ce{NH4F}$ and $\ce{NH4HF2}$ in water is complete, I assume:
$$\ce{NH4F -> NH4+ + F-}$$
and
$$\ce{NH4HF2 -> NH4+ + HF2-}$$
Can I calculate the amount of $\ce{HF}$ in these ...
- 421
-1
votes
1
answer
1k
views
Methyl Orange Indicator-Reason for small amount of NaOH [closed]
I used methyl orange as my indicator to titrate a weak acid:
At first, I added 3 drops of methyl orange to a solution of the weak acid, $\ce{CH3COOH}$, and the solution turned red. Then, after adding ...
-1
votes
1
answer
3k
views
Calculate pH at equivalence point [closed]
Calculate the pH at the equivalence point of a titration of 62 mL of 0.1 M $\ce{CH_3NH_2}$ with 0.20 M HCl. The $\ce{K_b}=4.4\cdot10^{-4}$.
At the equivalence point, the moles of CH3NH2 equals the ...
4
votes
4
answers
4k
views
Why does the degree of dissociation change when we dilute a weak acid even though the equilibrium constant is constant?
$K$ represents the ratio of concentrations of molecules in a solution at equilibrium, which means that $Q_\mathrm{r}$ (that ratio at any given point) looks to be identical to $K$. In other words, the ...
-1
votes
2
answers
1k
views
Calculate pH of a mixture of a strong base and acid. Knowing only the pH, wt/v%, and volume of both solution. [closed]
Title explains all. I have been stuck on this for an hour and for some reason cannot understand it. I have tried to do an ICE table but get stuck halfway as I do not know whether I would use the w/v ...
5
votes
1
answer
643
views
Why do my equilibrium calculations on this HF/NH4OH buffer system not match those in literature?
I've been trying to reproduce Figure 2 from this research paper (full text available).
The Problem
However I can't seem to get the same values as in the paper. I did the math both by hand and with ...
- 161
3
votes
2
answers
5k
views
Why doesn't a buffer solution change ph(Appreciably?)
Consider a buffer solution containing weak acid $\ce{CH3COOH}$ and its salt $\ce{CH3COONa}$:
\begin{align}
\ce{CH3COOH &<=> CH3COO- + H+} \tag{1}\\
\ce{CH3COONa &-> CH3COO- + Na+} \...
- 4,197
1
vote
1
answer
555
views
Acid-Base buffer question
Calculate the change in pH of a buffer made by combining $\pu{500 ml}$ of $\pu{0.1 M}$ $\ce{CH_3CH_2COOH}$ and $\pu{500 ml}$ of $\ce{CH_3CH_2COONa}$, when $0.04$ moles of $\ce{NaOH}$ is added to the ...
2
votes
2
answers
47k
views
Finding new pH after NaOH added to buffer solution
I have a buffer containing 0.2 M of the acid $\ce{HA}$, and 0.15 M of its conjugate base $\ce{A-}$, with a pH of 3.35. I need to find the pH after 0.0015 mol of $\ce{NaOH}$ is added to 0.5 L of the ...
- 749
3
votes
1
answer
603
views
Why do acids usually completely react with bases?
When a neutralisation reaction happens, for example, $ \pu{100 mol l^-1}$ of $\ce{HCl}$ with $\pu{100 mol l^-1}$ $\ce{NH_3}$, why does all of the base and acid get converted to salt? Why isn't there ...
- 295