Questions tagged [titration]

A laboratory method to determine the concentration of an analyte in solution. The solution volume plays a key role in the analysis.

Filter by
Sorted by
Tagged with
0
votes
1answer
764 views

Why heating up things before H2C2O4 &KMnO4 titration? [closed]

In my school, there is a redox titration between H2C2O4 being titrand and KMnO4 being titrant. After adding H2SO4 to the acid to give an acidic medium for redox, the whole mixture inside the conical ...
1
vote
0answers
49 views

What is the electrode potential at the equivalence point if concentrations of titrant and titrand are going to be zero?

Let's assume that the titrand is $\ce{Fe^2+}$ and the titrant is $\ce{Cr2O7^2-}$. Then $$E = E^\circ_\ce{Fe^{2+}/Fe^{3+}} - \frac{RT}{nF}\ln\frac{\ce{[Fe^{2+}]}}{\ce{[Fe^{3+}]}}$$ $$E = E^\circ_\ce{...
0
votes
1answer
38 views

Regarding acid-base reactions, how does one know when a hydrophobic base substance is fully protonated?

When there's a weak base substance (hydrophobic powder), and it needs to be completely protonated by adding an acid (eg: HCl), how does one know when it's completely protonated? Since the powdered ...
-1
votes
1answer
954 views

Why does a colour change in neutralisation occur? [closed]

An indicator shows whether an substance is a base or an acid but during a neutralisation reaction the colour change occurs due to the solution be neutral (i.e pH is 7). But since the indicators only ...
0
votes
1answer
51 views

Experimental determination of pH [closed]

I am trying to determine the experimental pKa for two weak acids that were titrated against 0.20M NaOH. I have read elsewhere that you can take the point where the graph becomes steep and divide the ...
1
vote
1answer
536 views

Precipitation titration with Volhard method

In the Vollhard method Chloride is precipitated from a solution using escess silver ions. $$\ce{Ag+_{(aq)} + Cl-_{(aq)} -> AgCl_{(s)}}$$ After precipitation the solution is filtered and ammonium ...
-2
votes
4answers
1k views

Titration of Na2CO3 against HCl

$\pu{25 mL}$ of $\pu{0.125 M}$ $\ce{Na2CO3}$ is titrated with $\pu{0.100 M}$ $\ce{HCl}$. Given that $K_\mathrm{a1} = 4.3\times 10^{-7}$ and $K_\mathrm{a2} = 4.8\times10^{-11}$ for the diprotic acid $\...
1
vote
1answer
179 views

Finding mass percentage of components of a solid mixture

A workbook question asks: $\pu{2.184g}$ of a solid mixture containing only $\ce{K2CO3}$ ($\mathrm{FW = 138.2058}\pu{ g/mol}$) and $\ce{KHCO3}$ ($\mathrm{FW = 100.1154} \pu{g/mol}$) is dissolved in ...
0
votes
1answer
454 views

What are some example of the use of argentometric titration?

Like, we use alkalimetric titration to calculate the real concentration of table vinegar. What about argentometric titration?
0
votes
1answer
460 views

NaOH being added to Formic Acid (Please catch my error!)

I am adding 0.55 mL of 0.1M NaOH to 10 mL of 0.5M Formic Acid. Here are the values I calculated to use. Moles H+ : 0.5 * (10mL / 1000) = 0.005 mol Moles OH- : 0.1 * (.55mL / 1000) = 0.000055 mol ...
-3
votes
1answer
56 views

neutralization of a strong acid with a strong base [closed]

When a 1M H2SO4 is mixed with an equal volume of 1M NaOH, is the mixture acidic, basic, or neutral?
1
vote
1answer
2k views

When using a “dilute hydrochloric acid” solution, how diluted should it be?

Quite often when reading through some instructions or documentation or an outline that I've found online (EG: acid-base extractions), theres a step that involves using a "dilute hydrochloric acid ...
2
votes
1answer
55 views

pH throughout a titration

Estimate the $\ce{pH}$ of the solution that results when $\ce{75.0 mL}$ of $\ce{0.275 M HCl}$ is added to $\ce{50.0 mL}$ of $\ce{0.275 M Na2HPO4 (aq)}$. My book gives the successive $\ce{Ka}$ values ...
1
vote
1answer
220 views

Why doesn't pH = pKa1 in the buffer zone for this titration?

Below is an image from my textbook representing the titration curve for the titration of $5.00\ \mathrm{mL}$ of $0.010\ \mathrm M$ $\ce{H2S2O3}$ with $0.010\ \mathrm M$ $\ce{KOH}$, which has $\mathrm ...
1
vote
1answer
575 views

Why is sulphuric acid added in the ripper titration?

Ripper titration can be used to determine free $\ce{SO2}$ in wine by titration with iodine. The method requires sulphuric acid to be added to wine before titration. Why is this the case?
0
votes
0answers
27 views

EQPt pH of a Monoprotic Acid-Base Titration: Product of Molarites Over Their Sum

Context The Henderson-Hasselbalch equation is as follows. $$pH=-\log\big(K_a\big)+\log\bigg(\frac{[A^-]}{[HA]}\bigg)$$ One may follow its derivation in order to understand how it came to be, yet ...
-1
votes
1answer
263 views

Why potassium chromate can be used as indicator in Mohr method?

Both silver chloride and silver chromate are insoluble, so why is that silver chromate is precipitated before silver chromate? Why wouldn't both red silver chromate and white silver chloride form at ...
4
votes
1answer
226 views

Mathematical explanation of blank titration in Mohr method for argentometry

In my book it is written that in order to minimize systematic error in Mohr method for argentometry it is a common procedure to conduct a blank titration with $ \mathrm{Ag^+} $ against a $\mathrm{CrO_{...
0
votes
1answer
88 views

Working out pH of solution when excess NaOH is added

In a pH titration, $30\text{cm}^3$ of $\ce{NaOH}$ is added to $\pu{20 cm3}$ $\ce{CH3COOH}$. The concentrations of both solutions was $\pu{0.5 mol dm-3}$. $K_\mathrm{a} = \pu{1.7 x 10^{-5}}$ for $\ce{...
1
vote
1answer
5k views

Finding pKa from equivalence point on titration curve [closed]

Is there a mathematical proof/explanation of why $\mathrm{p}K_\mathrm{a}$ corresponds to the $\mathrm{pH}$ at $\text{Volume of titrant}/2$ at the equivalence point? A concise proof will suffice.
-1
votes
1answer
43 views

Titrations in three equibilums

You have three solutions: 0.1 M solution of a weak monovalent acid 0.1 M solution of a strong monovalent acid 0.1 M solution of a weak divalent acid Each solution is titrated with 0.15 M NaOH. What ...
1
vote
0answers
159 views

Determining the chemical formula of a polyiodide Salt

I've got a compound with formula $\ce{N(CH3)4.I(I2)_x}$. By mass I've got $\pu{0.138 g}$ of $\ce{I2}$ present out of $\pu{0.189 g}$ of polyiodide added. How do I find $x$? This is the exact part of ...
0
votes
1answer
737 views

Would the End Point and Equivalence Point be Labelled the Same?

I created two graphs of two different titrations : One graph was the titration curve of acetic acid with sodium hydroxide (weak acid-strong base) and the other was that of nitric acid with sodium ...
3
votes
1answer
4k views

Explaining the colour change in the potassium permanganate titration of iron(II) ions

In the redox titration: $$\ce{MnO4- + 8 H+ + 5 Fe^2+ -> Mn^2+ + 4 H2O + 5 Fe^3+}$$ the colour change which occurs is purple to colourless, because of the decreased concentration of permanganate ...
1
vote
3answers
345 views

How would a pH curve look like for titration of diluted weak base compared to concentrated one?

Let's say I take $\pu{80 g}$ of a weak base, dilute it with $\pu{50 ml}$ of water and titrate it with a strong acid. I get a titration curve. Now I take again $\pu{80 g}$ of the same weak base but ...
1
vote
0answers
90 views

Is endpoint pH concentration dependent? Choosing an acid/base indicator

We use titrations to determine analyte concentrations with a standardized titrant and an acid/base indicator, BUT how do we choose the indicator? It is my understanding that indicators are supposed to ...
-5
votes
1answer
57 views

What effect, if any, would each of the following actions have on the calculated concentration of the NaOH in this experiment? [closed]

What effect, if any, would each of the following actions have on the calculated concentration of the NaOH in this experiment? (e.g. would the calculated concentration be higher, lower or the same?) ...
2
votes
2answers
578 views

What does the small, steep curve at the very beginning of a weak acid strong base titration curve come from?

I understand that a buffer solution is being made, but I don't understand why the titration curve is different from a strong acid strong base one (apart from the steeper pH change). I understand the ...
3
votes
1answer
519 views

What does “the magnesium salt of EDTA” mean?

I am attempting to prepare an ammonium chloride/ammonium hydroxide buffer solution ($\ce{pH}=10 \pm 0.1$) for titrating water hardness with calgamite and EDTA. In the 17th Edition of the Standard ...
-1
votes
1answer
60 views

Calculation of composition of drain cleaner

Important note: I'm an eighth-grader. I taught myself chemistry to organic chem using an arsenal of textbooks*, but I have gotten things wrong, namely resonance. Please read above (also this if you ...
-1
votes
1answer
3k views

Find the half equivalence point

How to find the half equivalence point knowing the pH, molarity, titrant added at equivalence point? This a fairly straightforward and simple question, however I have found many different answers to ...
1
vote
1answer
58 views

Shouldn't weak acids act as strong ones in alkaline solutions? [duplicate]

A weak acid in water dissociates reversibly as follows: $$\ce{XH <=> X- + H+}$$ A strong base is one which dissociates completely. Now, let's assume we're doing acid-base titrations, adding ...
0
votes
1answer
213 views

Finding the concentration of hydrochloric acid by titration

In a class experiment, $\pu{20 mL}$ of hydrochloric acid was diluted with distilled water to $\pu{500 mL}$. $\pu{20 mL}$ of this diluted solution was added to $\pu{20 mL}$ of $\pu{0.1 M}$ sodium ...
-2
votes
1answer
101 views

Why can we ignore the weak conjugate base/acid when calculating the pH in a titration problem? [closed]

Take the reaction 350 mL of 0.8M HCN and 0.6M NaOH for example. The problem asks us the calculate the pH when we add 500 mL of 0.6M NaOH into the 350 mL of 0.8M HCN (This is more than enough to ...
3
votes
2answers
1k views

How does an acid prevents or discourges oxidation of iron?

In the titration of $\ce{KMnO4}$ with Mohr's salt, I have learned that sulphuric acid prevents oxidation of $\ce{Fe^2+}$ to $\ce{Fe^3+}$ in the solution before the actual titration. How does the acid ...
3
votes
0answers
4k views

Why Mohr's salt and not FeSO4 in titration? [closed]

During titration of $\ce{KMnO4}$, we use Mohr's salt instead of ferrous sulphate salt to prepare the standard salt solution. Is it done to prevent oxidation of $\ce{Fe^2+}$ to $\ce{Fe^3+}$ before the ...
-1
votes
2answers
890 views

Lab Methods for Determination of Phosphoric Acid Concentration

Dear stack exchange, For my next lab session we have been tasked to come up with two different methods for determining the concentration of an unknown sample of phosphoric acid. Design at least ...
-2
votes
1answer
98 views

Is the following procedure for antacid titration correct? [closed]

I'm trying to check which antacid is more effective by determining the amount of $\ce{HCl}$ they can neutralize. Take $\pu{10 mL}$ antacid suspension and add excess $\pu{1 M}$ $\ce{HCl}$. Back ...
-1
votes
1answer
270 views

calculating ph of a mixture of acids

I came across a question that couldn't find the answer to and i couldn't find the answer anywhere. The question is the following. You have a soltion created by dissolving HCN and HBrO in water (T = ...
0
votes
1answer
953 views

Substitute for alkali-iodide-azide reagent for BOD test of water samples

To measure the biological oxygen demand (BOD) of water samples, I am following a procedure that uses manganese sulphate, $\ce{H2SO4}$, and titration with standard sodium thiosulfate solution. Alkali-...
5
votes
1answer
58 views

How do you experimentally calculate the ionization constant of the carbonate ion?

Given sodium hydrogen carbonate, $\ce{NaHCO3}$, as well as hydrochloric acid, $\ce{HCl}$, how would you experimentally determine the ionization constant for the carbonate ion, $\ce{HCO3-}$? By ...
6
votes
1answer
100 views

How much additional hydrochloric acid should be added to arrive at ‘excess acid’?

I am an IB student. And I am trying to find the mass percentage of $\ce{NaHCO3}$ in antacid. I am dissolving the antacid in $\pu{0.1 M}$ $\ce{HCl}$ solution. So, first of all I conducted some ...
1
vote
0answers
48 views

Hacking a pH meter and digital burette to partially automate a titration [closed]

This is a chemistry question about experimental techniques and technology. I would like to connect a digital burette (Brand Titrette) and a pH meter to a computer and automate data acquisition to ...
6
votes
3answers
7k views

Why the colour of KMnO4 at the end point of titration may disappear after some time?

In the redox titration of $\ce{FeSO4}$ with $\ce{KMnO4}$, the colour change of the solution at the end point is colourless to light pink. Most laboratory manuals and books advice us to check whether ...
3
votes
2answers
583 views

Acid-base titration: Calculate pKa with only three values given

There's an unkown acid, diluted with an unknown amount of water and titrated with $\ce{NaOH}$. After adding $\pu{10.00 mL}$ $\ce{NaOH}$, a $\mathrm{pH}$ value of $4.65$ is measured. After ...
0
votes
1answer
4k views

What is the product of the titration of potassium permanganate and iron(II) sulfate?

I recently did an experiment at school, where I had to titrate KMnO4 with FeSO4. The solution was colourless, then turned yellowish until the end point was reached and it turned pink in one drop. ...
1
vote
0answers
282 views

Colour change acid-base titration

I titrated orange juice with NaOH. I used no indicator, but at around the point of inflection, the juice changed colour to a more mustard-ish colour. What is the reason for this colour change?
3
votes
1answer
1k views

When an iodide/iodate solution is acidified with H2SO4 instead of thiosulfate, why should it be titrated immediately?

My class is currently performing a reaction to determine the oxidizing power (i.e. the amount of hypochlorite) of household bleach. The general process is as follows: Standardize thiosulfate to be ...
1
vote
1answer
4k views

What primary standard acid can be used to standardise NaOH solutions by titration?

I've done an experiment to standardise $\ce{NaOH}$ using oxalic acid. What other primary standard acid can be used to standardise $\ce{NaOH}$? Can $\ce{HCl, H2SO4, HNO3}$ be used? I read up and ...
1
vote
0answers
281 views

Why is double my half-equivalence point not equal to my equivalence point?

Tris pKA = 8, therefore at pH = 8, the volume is 4.5mL. However the equivalence point simply can't be at 9mL, looking at this graph. It should be between approximately 9.5 and 10.5, no?