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.

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195 views

Effects of Ka on the Half-Equivalence Point

I'm new to studying chemistry at a university level and am currently reviewing acid-base titrations. I am wondering about the relationship between your ionization constant for a weak acid ($K_\mathrm{...
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Why are synthetic pH indicators used over natural indicators?

Synthetic indicators seem to be exclusively used when determining the pH of a substance with an indicator (with the exception of that school experiment where you boil cabbage to demonstrate natural pH ...
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Polyprotic Acid Titrations

Titrating a mixture of strong and weak acids will yield endpoints such that the volume of base required to reach each endpoint will be different for each acid, e.g. in a mixture of HCl and CH3COOH, ...
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178 views

Why would CuSO4-EDTA drops be used in Pb titrations?

We use CuSO4-EDTA drops (4) when preparing our lead titration samples for final titration by EDTA. What mechanism would there be for adding this to a titration? What benefit does it produce on Pb ...
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193 views

How do I make a solution of spinach to titrate with pottasium permanganate? [closed]

My teacher said something about straining it but I didnt quite get it
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208 views

What are some ways to measure sugar concentration of fruits? [closed]

I've tried to do titrations using the quantitative Benedict's Solution and it was difficult to use as I do not have a way of keeping a constant temperature. I am currently using a Polarimeter to find ...
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122 views

Should the tip of the burette of an automatic titrator be immersed in the analyte?

In all the tutorials I found online, the tip of the burette (containing the titrant - NaOH) was immersed into the analyte solution. My question is: shouldn't the tip be out of the solution? Isn't ...
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Looking for experimental data for titration curves

I am looking for real, open source and free experimental dataset (not image, scan of table) of acid/base titration curves: pH versus titrant volume for many combination (strong/weak acid/base, ...
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320 views

What is the benefit of using a pH indicator reagent over pH strips or a meter?

I've recently started getting into chemistry a bit as a hobby. Nothing serious, just amateur level stuff mostly, primarily just to educate myself. Whenever I need to determine the pH level of a ...
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4answers
830 views

Is the titration of sodium carbonate with hydrochloric acid temperature dependent?

I am a chemistry teacher in a Cambridge school. In one of the titrations of sodium carbonate with HCl, there was one question asked: On heating the sodium carbonate solution before doing the ...
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1answer
194 views

Regarding Analysis for CO2 Absorption in NaOH

Background Lab experiment, packed glass column (random packing of metal/ceramic material), countercurrent gas absorption, flowrates measured using rotameters, $rt \approx 27^\circ C$. 2 N NaOH flows ...
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489 views

Does diluting the titration flask change the molarity

I was solving the following problem on a test and I thought the answer was A, but the answer is actually D. Below is the problem and my reasoning: Answer choice B is clearly incorrect because the ...
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1answer
66 views

Acid value of linseed oil

For this we weigh $\pu{1.015 g}$ of linseed oil which is dissolved in alcohol. 3 drops of phenolphthalein (pH indicator) are added and a solution of potassium hydroxide of concentration $C = \pu{9.5e-...
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2k views

Oxidation of sodium thiosulfate by iodine

When $\ce{Na2S2O3}$ reacts with $\ce{I2}$, it undergoes a redox reaction as $$\ce{2 Na2S2O3 + I2 -> Na2S4O6 + 2 NaI}$$ Sulfur is being oxidized from a $+2$ state to a $+2.5$ state. Why isn't it ...
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286 views

Eriochrome Black T titration - Concentration of Indicator and endpoint

While not as frustrating an indicator as murexide, Eriochrome Black T's wine red to blue transformations provide significant challenges. The change from "fully wine red" to "fully blue with no trace ...
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191 views

Iodometric Titration - Iodine Crystal formation

During an iodometric titration iodide is oxidised to iodine by an oxidiser, and then titrated using standardised sodium thiosulfate. I have had no problems using iodate as the oxidiser, however, using ...
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335 views

How to detect equivalence points? [duplicate]

How do we detect equivalence point from a titration of an acid with a basic titrant from thу titration curve ($\mathrm{pH}$ vs. Volume of titrant added)? Can we predict an equivalence point just by ...
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106 views

Is volume of strong base used with strong acid same as volume used with weak acid?

At the equivalence point, why do we take volume of strong base used for titration of strong acid the same as the volume used for titration of weak acid? Shouldn't there be a difference? For example, ...
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Titration curves

If I were to model the titration of $30 \ \text{cm}^{3}$ of $ 3 \ \text{mol dm}^{-3}$ $\ce{CH3COOH_{(aq)}}$ with $3 \ \text{mol dm}^{-3}$ $\ce{NaOH_{(aq)}} $ , what would the equation look like (...
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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 ...
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92 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{...
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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 ...
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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 ...
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58 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 ...
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1answer
1k 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 ...
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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 $\...
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375 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 ...
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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?
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632 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 ...
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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?
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5k 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 ...
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57 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 ...
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288 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 ...
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662 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?
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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 ...
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355 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 ...
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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_{...
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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{...
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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.
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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 ...
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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 ...
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887 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 ...
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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 ...
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633 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 ...
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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 ...
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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?) ...
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751 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 ...
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690 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 ...
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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 ...
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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 ...