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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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1answer
283 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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1answer
6k 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.
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3answers
550 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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1answer
1k views

How to correctly prepare a standard solution?

Having just spoken to my teacher about the creation of a standard solution, and she suggested one way of doing it, however a previous chemistry teacher had told us a different way of doing it. My ...
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1answer
2k views

In a mixture of NaOH and Na2CO3, why doesn't phenolpthalein change its color until Na2CO3 is half neutralised?

Let us consider a mixture of $\ce{NaOH}$ and $\ce{Na2CO3}$. Based on what I have understood, double titration works in the below manner : Phenolpthalein turns pink when added to the mixture. As $\...
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1answer
390 views

Titration - Just need your judgement

A student investigated the volume of sulfuric acid that reacted with 25 cm3 sodium hydroxide. Describe a titration method the student could use in this investigation. {6 marks} My answer: Use the ...
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1answer
521 views

How can the standard deviation for a set of experimental value be interpreted in terms of precision?

I have read from many websites that the sample standard deviation can be used to measure the precision of experimental values. I understand that the lower the standard deviation the better, as it ...
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1answer
1k views

How to determine which combination of substances will give a buffered solution given target pH and Kb of each substances

What combination of substances will give a buffered solution that has a pH of 5.05? (Assume each pair of substances is dissolved in 5.0 L of water.) (Kb for NH3 = $1.8 × 10^{–5}$; Kb for C5H5N = $1.7 ×...
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1answer
4k views

Calculating the pH of the endpoint in a titration of weak acid and strong base

Show that the pH at the endpoint in the titration of $\mathrm{0.100\ mol\ dm^{-3}}$ ethanoic acid with $\mathrm{0.100\ mol\ dm^{-3}}$ sodium hydroxide is 8.72. The dissociation constant Ka of ethanoic ...
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1answer
166 views

How to solvethis problem related to redox titration?

A $1.0\ \mathrm{g}$ sample containing $\ce{BaCl2*2H2O}$ was dissolved and an excess of $\ce{K2CrO4}$ solution added. After a suitable period, the $\ce{BaCrO4}$ was filtered, washed and redissolved in $...
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1answer
409 views

Preparing a 0.030 M solution of potassium ferrocyanide trihydrate?

I am a little bit confused on what I am supposed to do. The instructions say to prepare 250 mL of this solution by measuring out in grams the amount of PFT using a 250 mL volumetric flask. Then it ...
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1answer
496 views

Strong Acid/Strong Base Titration

Bromothymol Blue is an indicator that turns yellow in acid, blue in base. If I were to titrate NaOH with HCl, what color should I look for at the equivalence point? Should I titrate until the ...
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1answer
2k views

How to prove at what pH the color of an indicator will change based on its pKa?

The equivalence point of an acid-base titration can be determined by choosing the appropriate colored indicator. This indicator is a weak acid $\ce{HA}$. The undissociated acid has a different color ...
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2answers
2k views

Calcium sulfate soluble in water

In the volumetric estimation of calcium in a given solution as calcium oxalate. We convert the calcium oxalate to oxalic acid by dissolving the former in hot (~70 °C) 2 N sulfuric acid solution. This ...
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1answer
480 views

Making a 10L HCl solution with 8.77% HCl in a 100 mL solution from a 16 M stock solution

How would you make 10L of HCl solution with 8.77% HCl in 100 mL from a 16M stock solution. Here's what I have tried so far: I put my percent HCl and got that down to match with the moles of HCl I ...
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1answer
924 views

Why is silver nitrate used for cyanide titration?

Or more to the point, since silver isn't exactly cheap: Why can't cuprous nitrate ($\ce{CuNO3}$) substitute for the pricier ($\ce{AgNO3}$) in cyanide titration? I assume that free cyanides bind ...
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2answers
2k views

Finding the Ka of a weak acid after addition of a strong base

When 50.00 mL of an unknown 0.2461 M weak acid are titrated with 0.1968 M NaOH, it was found after the addition of exactly 16.00 mL of base that the pH of the solution was 3.79. From this information, ...
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1answer
1k views

Acid-Base Titration: Do Acids and Bases Have the Same Coefficients of Moles if They Neutralize One Another?

The questions states: Ammonia has the formula $\ce{NH3}$. Household ammonia is a dilute aqueous solution of $\ce{NH3}$. Aqueous ammonia is a base that can neutralize acids. If 18.2mL of 0.800 M $\ce{...
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2answers
11k views

MaVa = MbVb - Limitations and Uses

We know that for strong acids with a $1:1$ mole ratio between all particles involved are suitable for use with the aforementioned formula for titration problems. I want to know the limits on this ...
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0answers
32 views

Calculating the solubility of aspirin in water

I am trying to investigate the relationship between the solubility of aspirin in water with the relationship to some variables. In my investigation, I seem to be stuck with the calculation of finding ...
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29 views

Determining the composition of basic copper sulfate by titrimetry

A colleague shared an undergraduate level classical gravimetry/titrimetry experiment on determining the stoichiometry of basic copper sulfate. I am looking for a reference for this type of experiment. ...
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1answer
47 views

Redox titration or iron(II)

The concentration of $\ce{Fe^2+(aq)}$ can be determined by a redox titration using A. $\ce{KBr}$ B. $\ce{SnCl2}$ C. $\ce{KMnO4}$ (basic) D. $\ce{KBrO3}$ (acidic) Can anyone please ...
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1answer
37 views

Could this solution be resolved by titration?

I have a mixture of $\ce{NH_4NO_3}$ and $\ce{NH_3}$ at $\ce{pH}$ of about 13. It is possible to determine the concentration of both on them by acid-base titration? I was told it's possible, and that ...
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How can a titration help me figure out the effect of rosmarinic acid on amylase activity?

So with my limited knowledge of rosmarinic acid, I am aware that it is an non-competitive inhibitor and can inhibit the enzyme, amylase. When starch is added to a solution of already mixed rosmarinic ...
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190 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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180 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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30 views

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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69 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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1answer
257 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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198 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 ...
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95 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 ...
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1answer
59 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 ...
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50 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 ...
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0answers
312 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?
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315 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?
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244 views

Determining the calcium content in cashews via titration?

I have been planning on an experiment for quite some time now (as part of my after-school chemistry club), but I still feel like I am missing something. Due to my family's calcium deficiency, I ...
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0answers
852 views

What is the role of the sulfuric acid in a titration between potassium permaganate and iron ammonium sulphate solution?

So basically my titration was of finding the concentration of potassium permaganate against an iron ammonium solution. In the iron ammonium sulphate solution it consisted of water, iron ammonium ...
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63 views

Could An Equivalence Point Be Calculated or Deduced Based on Limited Data with Accuracy?

I have recently been tackling a problem from one of my A-Level chemistry exercises on the topic of acids and bases, particularly with strong base and weak acid titration curves: A titration is ...
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0answers
700 views

Saponification Value of a fat/oil

The saponification value of a fat was determined by adding $\pu{9.0 g}$ of the fat to flask containing $\pu{50.0 cm3}$ of $\pu{1.00 M}$ ethanolic potassium hydroxide. The remaining solution was ...
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0answers
128 views

Formula for finding how much base to add to buffer to obtain a desired pH

Given: molarity and volume of the weak acid, molarity of the strong base, desired $\ce{pH}$, $K_{a}$ of the acid. I tried coming up with a formula to solve for the amount of base to add in order to ...
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How to Prepare a 80mL Carbonic Acid-Bicarbonate buffer solution of ph=7.4 in laboratory? [closed]

I have the following materials which I can use: 0.1 M sodium bicarbonate solution Sodium Bicarbonate powder 0.1 M HCL Distilled Water Universal Indicator It will be a great help if you can provide ...
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817 views

Redox Titrations Half & Full Equations

I was presented with the following problem and I am finding it difficult to present the half equations for the answers. I managed to produce the half-equation for the Iodine redox. $\ce{2I- -> ...
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554 views

Calculating the pH of soft drink [closed]

Me and my classmates are doing an experiment in order to determine the pH of Sprite. We are going to conduct a titration with NaOH. We are taking under consideration that the citric acid in Sprite is ...
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69 views

Dichromate-thio titration

Can dichromate in acidic media be titrated directly with buffered thiosulfate solution using $\ce{H2O2}$ as an external indicator instead of using $\ce{KI}$ which is a standard procedure? $\ce{...
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1answer
7k views

How do I find the moles of NaOH required to reach the equivalence point? [closed]

For each trial with the unknown acid, calculate the following: a) Moles of $\ce{NaOH}$ required to reach the equivalence point. I need help with part A. I have already solved and figured out the ...
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288 views

How can you perform an acid-base titration with antacids if substances, like aluminium hydroxide, are insoluble?

I am trying to perform an experiment in order to determine the efficiency of different antacids. An online search later shows that you add an HCl solution in a solution created with a base/antacid. ...
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0answers
359 views

Why isn't an Acid-base titration curve linear? [duplicate]

Sorry if this is a stupid question, but why is a acid-base titration curve not linear? As you add more acid solution to a basic solution, shouldn't the pH of the basic solution slowly go up in ...
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348 views

Precipitation of Calcium ions in basic Sodium Hydroxide solution?

I recently conducted an EDTA titration of milk to find its Calcium contents. I got a value significantly smaller than the theoretical value. (≈10 times smaller). I made $50ml$ samples to which I added ...
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38 views

Neutralization equation [closed]

If I have cider vinegar and want to calculate the total moles of acid found in it, how can I do it? I have the moles of NaOH and I know that it includes both acetic and malic acid but how can I ...
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3k views

Finding the pH among HF and KOH

Okay I ran into this question in homework. A 100.0 ml sample of 0.20M HF is titrated with 0.10 M KOH. Determine the pH of the solution after adding 200 ml of KOH. The Ka of HF is 3.5 x 10-4? Oh yeah ...