The branch of chemistry concerned with identifying and quantifying the chemical constituents of matter.

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coordination chemistry and werners theory of complex compounds [on hold]

A solution containing 2.674 g of $\ce{CoCl3*6NH3}$ was passed through the cation exchanger. The eluted solution yields 4.305 g precipitate of $\ce{AgCl}$ with an $\ce{AgNO3}$solution. ...
3
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26 views

Choosing the instrumental techniques for chemical analysis [on hold]

Since every technique has its goods and its bads characteristics, it's a bit hard for me to choose between them to determine specific elements, methods such as UV-VIS spectroscopy, IR spectroscopy, ...
0
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12 views

Qualitative spectrographic analysis

In order to identify the presence of a specific element, one must identify at least three ultimate lines of that element in the specter. Those lines are the ones with the highest intensity. I ...
2
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0answers
16 views

Know any micropipettor that is acid resistant?

We pipet concentrated nitric and hydrochloric acids. our current pipettor is rainin lite but its piston is metal and thus corrode easily. We discussed this with our inhouse technician and he ...
2
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1answer
22 views

What is the mechanism for electrospray ionization?

I've been asked to Descibe the ionization mechanism used in electrospray ionization I know that this is a desorption ionization source, which uses a high electrical field as the ionizing ...
6
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1answer
74 views

Estimate the concentration of HCl and volume of 6 M HCl required to complete precipitate each of the given salts

In our chemistry lab we performed the following experiment below. Given that $K_\mathrm{sp}(\ce{AgCl}) = 8.2 \times 10^{-11}$ and $K_{\mathrm{sp}}(\ce{PbCl_{2}}) = 1.7 \times 10^{-5}$ ...
4
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3answers
101 views

What are some books, websites, etc. where I can find the detailed protocol for standardization of sodium thiosulfate with dichromate?

I am looking for a book or website such as "Vogel's Textbook of Quantitative Chemical Analysis" where I can find methods for analyzing/standardizing a particular species easily. I am not looking for ...
4
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2answers
38 views

2,4-dinitrophenyl hydrazine test

I found this reaction over here: which illustrates the carbonyl test but looks fuzzy. Assuming that the R in the product is a typo for H, I couldn't conserve the number of Nitrogen atoms. ...
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1answer
38 views

Is the following reaction redox? [closed]

Is the test of sulphur using sodium nitroprusside a redox reaction?
3
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1answer
21 views

Stability constant of complexes

I know that this constant tells us the strength of the interaction between the metal and the ligand, so should it also mean that the higher the constant, the stable the complex ? I need to make sure ...
4
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33 views

Different elution profiles of carvacrol and thymol

I have identified carvacrol and thymol via thin-layer-chromatography and via gas chromatography On a normal silica plate the thymol has a higher Rf-value then carvacrol. The explanation for this would ...
1
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1answer
36 views

Photometric titration

If we have $\ce{A + T -> P}$ where $\ce{A}$ is the analyte, $\ce{T}$ is the titrant, and $\ce{P}$ is the product, photometric titration happens only in one condition, that one of the following ...
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8 views

Optional determination techniques in AAS

I have tried to find information about this case but I couldn't find anything specific. The key point of instrumental methods of analysis, is for the student to be able to know which one of the ...
6
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1answer
27 views

Determination of mercury in AAS

Its known that the only method to determine mercury in atomic absorbtion spectroscopy is the cold vapor method. What is the reason that mercury can't be determined with other methods, such as flame, ...
2
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0answers
20 views

How to confirm the type of bonding taking place between two substances?

For example ink on paper: how can I confirm that the bonding is van der Waals and not covalent? Similarly, the same question can be asked about other interaction such as hydrogen bonding, ionic ...
3
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2answers
54 views

Converting g/L to mol/L

I know I should divide $\mathrm{g~L^{-1}}$ by the molar mass of the substance, but I don't seem to find the specific answer on Google. So just to be sure: If I have ...
5
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0answers
21 views

Atomizers in AAS

Electeothermal atomizer ( graphite furnance ) and flame atomizer, are the instruments which help us to convert the analyte into the gas state and they both achieve that. My question is, what's the ...
13
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47 views

Manuals for a Cahn TG-171 Thermogravimetric Analyzer

Recently a Cahn TG-171 Thermogravimetric Analyzer was donated to my school. We did not get a service or user's manual with it, and some of it still needs to be put back together. I have tried to ...
1
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1answer
38 views

How does standardising a secondary standard solution make it suitable as a standard solution?

I know that a standard solution in volumetric analysis must have an accurately known solution. Primary standard solutions (e.g. anhydrous sodium carbonate) can be used straight-away as they follow the ...
3
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1answer
67 views

Identify this solution

The solution is emerald green in colour. When added with water, it gives a pale blue solution When reacted with $\ce{BaCl2}$, it gives a sky blue solution and a white precipitate. When reacted with ...
7
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1answer
34 views

Wavelength extention in AAS

Theoreticly, the width of the spectral line in AAS (atomic absorbtion spectroscopy) is 10^-5, but in fact there happens an extention of it and it becomes 0.002-0.005. There are some factors which ...
7
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2answers
59 views

Way to detect lead in gasoline

Is there any way that i can detect lead in gasoline, not by sending of to a lab but to be able to do this by myself?
6
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2answers
150 views

How is drift due to static electricity eliminated from an analytical balance?

I've recently encountered a problem when using an analytical (0.1 mg accuracy) scale to determine the mass of a sample of ferrocene powder. The reading in the balance seems to drift either upwards or ...
2
votes
1answer
49 views

Auxochrome groups

Functional groups like $\ce{OH}$, $\ce{NH2}$, attached to nonsaturated compounds (chromophores) are called auxochromes. These groups tend to shift the wavelength to the infra-red area which is called ...
3
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1answer
32 views

Derivation spectrum

My book doesn't seem to properly explain the importance of derivating the Gaus spectral line, neither the meaning of it, so my questions are : 1.What do the spectral lines of 1st, 2nd, 3rd and 4th ...
3
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1answer
29 views

Smith Hieftje correction method

I completely don't understand how this method works. My book says that this method works by the principle of self-absorption which occurs by the emitted radiation of hollow cathode lamp when it works ...
1
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2answers
31 views

Why are hollow cathode lamps used for atomic absorption spectroscopy?

In 1955, it was proposed that hollow cathode lamps are good emission sources for monochromatic radiation, and thus for atomic absorption spectroscopy (AAS). In looking into the topic, I've read that ...
3
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1answer
38 views

Instrumental methods of analysis

I am taking the instrumental methods of analysis course. Our job is to find the unknown mass of $\ce{Fe}$ which is added, by measuring the absorbance of different solutions with ortho-fenantroline. ...
6
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1answer
54 views

Comparing wt% to at% which is normalized to 100%

I have measured the element composition of a sample using ICP-OES, and reported my results in wt%. A study which has analyzed the same sample types, but with an electron microprobe, has reported their ...
2
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1answer
44 views

Spectral Peak-Picking in MS Excel

I'm working often with spectral data of various gases, and the bulk of the data analysis is assigning the peaks with maximum signal (y-axis) to frequency (x-axis). Often we have several thousand data ...
2
votes
1answer
35 views

Yeast Fermentation with YPD + Apple Juice

I am working on a project for my General Chemistry class. I am trying to compare the EtOH production (and the rate of EtOH production) between seven types of yeast strains by fermenting the YPD ...
1
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1answer
52 views

How to calculate the required concentration for sodium sulfite to remove oxygen as an oxygen scavenger from a solution?

If I know the amount of oxygen in such a solution, how can I know the required concentration of sodium sulfite to be used and react as oxygen scavenger?
0
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1answer
40 views

Spins spin coupling on proton NMR for an aldehyde?

On a proton NMR, does the hydrogen in the CHO group cause coupling, or get coupled itself? Specifically, I a considering 2-methylpropanal. I cannot decide whether the H in the aldehyde group would be ...
1
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1answer
28 views

Detect Polyethylene

How can we detect polyethylene from a distance? The method should be mobile as I am thinking of employing it a mobile robot. I have no idea about it. Any suggestion or external link would be ...
2
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1answer
42 views

Colorimetric test to measure dissolved oxygen in salt water

Are there any simple colorimetric tests for measuring the dissolved oxygen in salt water, which do not involve titration like in Winkler method ? i.e. Are there any chemical reagents, which when ...
2
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24 views

Is Polymorphism accompanied with an energy change?

Differential Scanning Colorimetry (DSC) is a technique used to identify Polymorphism by revealing two melting points of a pure crystalline structure. DSC shows a peak associated with the formation ...
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1answer
63 views

How to find pKa given absorbances and pH [closed]

If the absorbance of one of the buffer solutions (pH = 4.623) was 0.319 and the absorbance of the basic solution was 0.625, what is the $\mathrm{p}K_\mathrm{a}$ of the indicator? Include activity ...
2
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1answer
58 views

Finding is the concentration of H⁺ in a benzoate buffer solution after adding HCl

Q: A buffer with a pH of 4.44 contains 0.21 M of sodium benzoate and 0.12 M of benzoic acid. What is the concentration of $\ce{[H^+]}$ in the solution after the addition of 0.050 mol of $\ce{HCl}$ to ...
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1answer
61 views

What happens if don't use MgCl₂ in buffer solution in Ca²⁺/Mg²⁺ titration?

What happens to a complexometric titration of calcium carbonate (analyte) with $\ce{EDTA}$ (titrant) when no magnesium(II) chloride crystals are added to the buffer ($\ce{NH3/NH4^+ + EDTA}$) solution? ...
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1answer
27 views

Analysis project to conduct [closed]

We have been asked to conduct an analytic project for chemistry. It is important that the project conducted hold social implications and the conclusion achieved help inform people better. Several ...
0
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23 views

How do you calculate the effect of adding more acid past the neutralization point? [duplicate]

In titrating a weak acid with a strong base, and given the mole values of each component at the endpoint and the pH there, how do you calculate the pH and species' concentrations after adding an ...
0
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1answer
42 views

3rd analytical group of cations

If a mixture of Mn$^{2+}$, Zn$^{2+}$, Co$^{2+}$, Ni$^{2+}$ and Al$^{3+}$ salts is dissolved in water, a white dim solution is obtained. I guess that the aluminium and zinc ions hydrolysed and the ...
0
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1answer
36 views

Finding out the concentration of oxygen in water

I read in a biology course that you can determine the concentration of oxygen in water by adding some $\ce{NaOH}$ and then a small amount of $\ce{MgCl2}$. They say that a dark coloured precipitate is ...
2
votes
1answer
79 views

Molarity vs Normality in labeling sulfuric acid

Molarity (M) is defined as moles of solute per liter of solution while Normality (N) is defined as moles of reacting units per liter of solution. Most texts use sulfuric acid as an example to ...
0
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1answer
47 views

How to determine methane percentage at home?

Suppose I have gas bottle and gas cooker. Suppose I have propane in my bottle and I suspect it is diluted with unknown gas. How can I measure with simple instruments, how many propane I have ...
0
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1answer
42 views

Purifying washing soda

I bought a box of A&H Washing Soda, the packaging of which implied that it was pure washing soda (sodium carbonate). On dissolving it in osmotically-purified water, however, I found that the ...
3
votes
2answers
47 views

How to report pH values?

I have measured the pH in the water-soluble fraction of a powder. I weighed in a certain amount of powder and a certain amount of water, and extracted the water-soluble fraction. I then measured the ...
3
votes
1answer
55 views

Testing for the presence of Hexamethylenetetramine / Formaldehyde [duplicate]

I read in Russian popular articles that it is allowed to preserve herring/fish with Hexamethylenetetramine in Europe. Since Soviet times, I like to buy salty herring and marinade it with Vinegar. The ...
1
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1answer
58 views

How to calculate the oxidation state and the number of equivalents oxidized with YBa₂Cu₃O₇

I've hit some trouble with these calculations and need help sorting out confusion. In the lab we synthesized $\ce{YBa2Cu3O7}$, per the lab manual $\ce{Y, Ba, O}$ have the usual charges of +3, +2, and ...
2
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1answer
45 views

Why do electrons not get paired up in [Fe(H2O)5NO]2+?

The magnetic moment of [Fe(H2O)5NO]2+ is 3.87 Bohr magneton, which implies there are 3 unpaired electrons. Since iron is in +1 oxidation state (due to charge transfer with nitrosyl group), it's ...