Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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

0
votes
1answer
22 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
23 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
26 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 ...
0
votes
0answers
21 views

Neutralising with strong/weak acids [duplicate]

So I've been thinking about a question I've come across recently: It goes like this - Hydrochloric acid (HCl) is a strong acid. Properties of a solution of 1.00mol dm–3 hydrochloric acid include: ...
-1
votes
1answer
61 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
35 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
52 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 ...
-1
votes
3answers
106 views

Titration of Na2CO3 against HCl

$\pu{25mL}$ of $\pu{0.125M}$ $\ce{Na2CO3}$ is titrated with $\pu{0.100M}$ $\ce{HCl}$. Given that $K_{a1} = 4.3\times10^{-7}$ and $K_{a2} = 4.8\times10^{-11}$ for the diprotic acid $\ce{H2CO3}$, ...
1
vote
1answer
97 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
55 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
43 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
36 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?
0
votes
1answer
182 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
42 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
80 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
203 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
13 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
38 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 ...
0
votes
0answers
39 views

Why do we need iodometry?

In case of iodometry where we need to find the concentration of an oxidant, we react it with $\ce{I^-}$ and check how much $\ce{I_2}$ is produced. Then we use a reducing agent with known volume & ...
4
votes
1answer
112 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
39 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
1k 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.
0
votes
0answers
44 views

Will potassium oxalate form stable complexes with Al 3+ AND Fe 3+ in an acidic solution?

I am trying to perform a complexometric titration of both Al 3+ and Fe 3+ in a sulfuric acid solution. I would be measuring the titration using a thermistor. The goal in this would be to complex all ...
0
votes
0answers
340 views

Does Hydrochloric Acid react with Calcium Phosphate?

I am trying to do a variant on the traditional eggshell calcium carbonate back titration, which is done by using HCl. Would this work with bones, which contain calcium phosphate instead?
0
votes
1answer
33 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
85 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
222 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
1k views

Explaining the colour change in the potassium permanganate titration of Fe2+ ions

In the redox titration: $$\ce{MnO4- + 8H+ + 5Fe^2+ -> Mn^2+ + 4H2O + 5Fe^3+}$$ the colour change which occurs is purple to colourless, because of the decreased concentration of permanganate ions. ...
1
vote
0answers
37 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 ...
0
votes
0answers
502 views

Calculate pH at equivalence point given one concentration

Question: What would the pH be at equivalence if oxalic acid is titrated with $\pu{0.10 M}$ $\ce{NaOH}$? Attempt: I tried doing the problem, but felt like it was missing details. Wouldn't I need ...
-4
votes
1answer
35 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?) ...
3
votes
2answers
270 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
193 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
50 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
763 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 ...
0
votes
0answers
32 views

Standardising sodium hydroxide

Using an average titration volume of $\pu{26.8mL}$ of sodium hydroxide, calculate the concentration of the $\ce{NaOH}$ solution. ($\ce{NaOH}$ & $\ce{KH(C8H4O4)}$ molar ratio = $1:1$). Given that ...
0
votes
0answers
286 views

The effect of temperature increase on sodium hypochlorite concentration in bleach

We are completing an experiment on the effect of temperature increase on sodium hypochlorite concentration in bleach (as calculated using excess iodine and sodium thiosulfate titration) I assume ...
1
vote
1answer
43 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
85 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
35 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 ...
2
votes
2answers
299 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
2k 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
438 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
58 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
179 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
525 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
49 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 ...
5
votes
1answer
85 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 ...
0
votes
0answers
132 views

Why does nothing happen at first during titrations? [duplicate]

Take, for example, the reaction between Sodium Hydroxide and Hydrochloric Acid: NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l) Say you have a conical flask of NaOH with Phenolphthalein indicator in it. ...
1
vote
0answers
39 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 ...