Questions tagged [experimental-chemistry]

This tag should be applied to questions relating to the theory, design, techniques or performance of chemical experiments. This includes but is not limited to theoretical structures, expected products, thermal calculations, and empirical analysis. Additional tags should be applied to narrow down the field of research.

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A chemist combines 300mL of a 0.3 M Na2SO4 solution with 200 mL of a 0.4 M BaCl2 solution. How many grams of precipitate form? [closed]

Answer key: 233.4g 21.0g 18.7g No precipitate is formed 58.5
-4 votes
0 answers
21 views

Which solvent can i use to dilute silicone oil so that its transparency can be maintained? [closed]

how to make transparent diluted silicone oil for shoe shiner Silicone oil doesn't dissolve in white spirit I want to dilute a silicone oil. Can u people suggest me a good solvent
5 votes
1 answer
63 views

How to make a thin layer of crystalline barium titanate on copper substrate?

Is it possible to create a thin $\ce{BaTiO3}$ crystal layer on a copper plate by putting the plate in a beaker, pouring in heated hydrofluoric acid that has been saturated with $\ce{BaTiO3}$ powder ...
-2 votes
0 answers
16 views

How can i find protocol for Bocylation of Amino-PEG4-Acid and its deprotection?

I intend to make mesoporous silica nanoparticles(MSNP) with a peptide attached to it. Between my target peptide and MSNP, i use Amino-PEG4-Acid as a linker molecule. Due to the order of assembling ...
5 votes
2 answers
159 views

Synthesizing Cyclotetrazane from Hydrazine and Diazene?

Could cyclotetrazane — a compound with nitrogen atoms arranged in a square configuration — be synthesized? A hydrogen atom would be bonded to each vertex (nitrogen atom): Could cyclotetrazane be made ...
13 votes
3 answers
7k views

Is argon preferred over nitrogen for maintaining an inert atmosphere?

I recently started a project in a new lab group over the Summer that does medicinal chemistry. Unlike in the undergraduate labs, they use argon instead of nitrogen for their inert atmosphere work. ...
4 votes
2 answers
291 views

Using potassium dichromate and sulfuric acid to clean test tubes after Tollens' Test

In school, we had an experiment to find out the biomolecules contained in the different foodstuffs. After doing Tollens' test which turned out to be positive, our teacher instructed us to clean the ...
5 votes
0 answers
4k views

Should I round an experimentally determined reaction order to an integer?

For a lab experiment I did, I calculated the reaction order for one of the reactants using data from two trials, both rates, and the concentration of that reactant during each. $$ \frac{\text{Rate}_1}{...
-3 votes
0 answers
21 views

Iodimetric titration for reducing agent

I am stuck at point, where I want to find the % Purity of my analyte with iodimetric titration as the analyte is very strong reducing agent. I found reference which mentions titration with iodine in ...
2 votes
0 answers
27 views

TLC experiment interprentation

I am having difficulty interpreting the results of an identification test involving six different standards (dyes) in an unknown mixture of dyes, using silica gel TLC plates and acetone as the mobile ...
0 votes
1 answer
56 views

Minimum volume of benzene with percentage yield

The overall yield for the synthesis of N-phenylethanamide from benzene was found to be $35.2\%$. Calculate the minimum volume of benzene, in $\mathrm{cm}^3$, required to make $10.0\, \mathrm{g}$ of N-...
12 votes
1 answer
2k views

What is the fabric in heating mantles made of?

An ordinary lab heating mantle often has a white fabric coating for the flask compartment, which looks like an inorganic fiber: Image source I'm pretty sure that for some time in the past ...
3 votes
3 answers
108 views

Can uncertainty be higher after averaging?

I remember my chemistry teacher said something about how the uncertainty for the average value shouldn't exceed the uncertainty of the uncertainty for the individual values because the reason why we ...
2 votes
1 answer
99 views

Difference between change of enthalpy of neutralization between copper and manganese carbonate

I was doing a calorimetry experiment to calculate the change in enthalpy during neutralization reactions between metal carbonates and hydrochloric acid. I experimented with 5 metal carbonates: ...
4 votes
0 answers
658 views

Why isn't my Cu2O Cuprous Oxide red

A thin film sample of polycrystalline Copper(I) Oxide (Cuprous Oxide, $\ce{Cu2O}$) on quartz looks reddish in the center but bluish/grayish on the sides where the film is thicker. The same thin film ...
2 votes
1 answer
151 views

Effect of particle size on yield of copper acetylide

To avoid pure trial and error, I need some examples of experiments already done with (possibly ammoniacal) aqueous solutions, particles/precipitates of copper (both oxidation states) salts, and ...
7 votes
4 answers
18k views

What current and voltage are best for electrolysis rust removal?

I weld carbon steels all the time, and sometimes I get parts from the scrapyard. Unfortunately, these parts are generally oxidized, so I've been assembling an electrolysis tank for it. This tank ...
5 votes
1 answer
416 views

Does the side of filter paper matter?

A question has bothered me for quite a long time. I noticed some filter papers have a smooth side and a rough side. Does it matter (in theory) if I use the smooth side or the rough side for gravity ...
1 vote
1 answer
44 views

Need help with synthesis of iron (II,III) oxide (Fe₃O₄) nanoparticles

I am attempting to synthesize iron (II,III) oxide nanoparticles (Fe3O4). I have some iron acetate and have seen some literature where people have synthesized Cu nanoparticles using a polyol process. ...
6 votes
4 answers
2k views

How to distinguish silver chloride, bromide and iodide?

When we test for chloride, bromide and iodide ions we use the obvious silver nitrate and dilute nitric acid test. However distinguishing between the precipitates is often quite tricky. How can we tell ...
-5 votes
1 answer
1k views

Preparation of potassium cyanide from potassium ferrocyanide via HCN

Does anyone have any experience with the preparation of potassium cyanide from potassium ferrocyanide via $\ce{HCN}$ method? I did some math and am going to proceed eventually, any advice would be ...
4 votes
0 answers
41 views

Why cool a reaction down when adding reagents if you're only going to reflux subsequently?

I've seen several procedures using thionyl chloride (SOCl2) to make an ester, where the first step is to add the thionyl chloride to the reagent/solvent on ice or subzero temperature, followed ...
1 vote
0 answers
30 views

Trends in pKb for both acetic acid and water

I am trying to rationalise a result that I have recently measured in the lab. I'm measuring the pKb of different compounds in anhydrous acetic acid, using the procedure outlined in this paper (https://...
4 votes
1 answer
690 views

Extrapolating from a calorimetry lab to find a new delta T with different volumes and grams of substance

So, we just finished an AP chem lab where the question was basically: Given the results of the lab were that $\pu{5 grams}$ of $\ce{CaCl2}$ and $\pu{45ml}$ of water produced a $\pu{13.33 ^\circ C}$ ...
0 votes
4 answers
248 views

Storage of air and temperature sensitive reagents [closed]

What's your method for storing air/moisture and temperature sensitive reagents? For example: A solid. Should I just blow some argon, screw the lid, put parafilm and put it in the fridge? Can a ...
0 votes
1 answer
56 views

About whitish layer that formed on chocolate bar

I noticed a whitish layer on the surface of a chocolate bar that I ate yesterday. I looked at the pack where it was mentioned that, "Temperature and humidity changes may cause product to develop ...
0 votes
1 answer
87 views

Testing whether an unknown powder is wheat gluten (at home)?

Last week, I ordered wheat gluten to make seitan. I received some powder and attempted a recipe, which mixes 100g of water with 100g of gluten to form a sticky dough. However in my case, I only got a ...
10 votes
4 answers
8k views

What is the real pKa of water?

What is the $\text{p}K_\text{a}$ of water? A simple google search yields the value $15.74$, but this site and this paper say it's $14.0$. According to my understanding, the correct answer should be $...
1 vote
0 answers
50 views

What precipitate is formed when a copper coin is dissolved in concentrated nitric acid?

The method being used. I am currently carrying out a school project where I am determining the copper content of 1p coins. The coins used are British 1 pence coins dated before 1992 as after this year ...
-1 votes
1 answer
42 views

What could be used to thicken Ferric Chloride solution?

I'm curious if it's possible to thicken Ferric Chloride so I can control it more on a less than horizontal surface ?
7 votes
1 answer
1k views

Mixing naphthalene, formaldehyde and sulfuric acid (Marquis reagent + naphthalene)

Excuse me if this a dumb question but it has haunted me for years. Back in my old school days I mixed naphthalene, formaldehyde and sulfuric acid in a mad attempt to make $\mbox{2-Methoxynaphthalene}$...
2 votes
0 answers
43 views

Calculate percent composition from XPS?

I have an XPS graph and was wondering how to calculate percent composition. I do have the percent compositions that were determined from the graph, but I don't know how they were found. For reference, ...
2 votes
2 answers
9k views

Is styrofoam soluble in gasoline or paint thinner?

Why doesn't gasoline or paint thinner melt through Styrofoam when I try it yet there are videos of others melting Styrofoam in gasoline and paint thinner? Is there something I am doing wrong? This is ...
5 votes
1 answer
181 views

Problem digesting sample for Ti analysis using ICP-OES

I'm having trouble digesting a paper sample for $\ce{Ti}$ analysis using our ICP-OES. I've been digesting my ash samples with 50% $\ce{H2SO4}$, but I'm still getting lower $\ce{TiO2}$ results than the ...
0 votes
1 answer
115 views

Is this evidence that solubility of sodium bicarbonate<sodium carbonate?

Someone introduced $\ce{CO2}$ into saturated $\ce{Na2CO3}$ solution, and observed that white precipitate is produced. He therefore claims that $\ce{NaHCO3}$ has less solubility than $\ce{Na2CO3}$. His ...
1 vote
2 answers
53 views

Oxidation of Isopropanol by Permanganate in Basic Solution

so I've been designing an experiment where I will explore the effect of isopropanol concentration on the colour change of a solution containing permanganate, isopropanol, and NaOH. I know that the ...
2 votes
0 answers
48 views

How can I refine my method of determining iron content in spinach?

I have begun a chemistry experiment that attempts to determine how iron content in spinach is affected by the length of time it is cooked. Through research, I learned that iron content is often ...
18 votes
3 answers
14k views

What exactly happened when I added KOH to hydrogen peroxide?

I recently added a potassium hydroxide, $\ce{KOH}$, pellet to a small droplet of hydrogen peroxide (30 %), $\ce{H2O2}$. You could clearly see the potassium hydroxide dissolving in the droplet when ...
7 votes
2 answers
580 views

Question about the differences of white and grey NaH properties

We are having some problems with the next reaction in our lab. As you can see, is the sulfonylation of an indole in which we use NaH (60% dispersion in mineral oil) as a base. This reaction goes with ...
2 votes
2 answers
322 views

How do I synthesize salicylic acid?

I'm looking to synthesize salicylic acid in my school laboratory for an investigatory project. The Kolbe's reaction looks promising: Any suggestions on where to get the $\ce{CO2}$ from? Will the ...
0 votes
0 answers
58 views

How to remove hexane from nBuLi

As described in a paper, the authors removed the hexane from the nBuLi solution "under reduced pressure". I was wondering if anyone had any experience on how to proceed safely with this ...
5 votes
2 answers
166 views

Should I add more of a trihydrate chemical to a solution if recipe calls for hemihydrate?

I am running phosphate by the ascorbic acid method (SM 4500-PE, PDF), and making the antimony potassium tartrate reagent. Standard methods uses $\pu{1.3715 g}$ of $\ce{K(SbO)C4H4O6 * 1/2 H2O}$ per $\...
0 votes
0 answers
40 views

Some particles are observed inside the wall of glass vial

Recently, when I use glass vial, some particles are observed inside the wall. These particles are so small and transparent or maybe white-colored, so it is hard to observe during ordinary usage. But ...
0 votes
1 answer
70 views

Volumetric flow rate ratio calculation

I'm using two tanks of nitrogen and oxygen and mixing them in different ratios to change the oxygen partial pressure in the system. System is opened to the atmosphere through the venting pipe which ...
1 vote
1 answer
464 views

Assignment of NMR peaks of polystyrene

I’m having trouble identifying the peak around 3,75 ppm in the 1H-NMR spectrum of polystyrene measured at 400 Hz in CDCl3. Could someone please provide their perspective on it? I see it appear in a ...
0 votes
0 answers
68 views

What determines the pressure in the system when the gas tanks are opened?

I have two gas tanks of nitrogen and oxygen. Mixture of gases is created at specified composition and used in the system of interest. Let's say I want to create an atmospheric conditions in my system, ...
1 vote
1 answer
61 views

Could I expect any adverse reactions with this ink mix?

Our newest R&D project for a permanent, outdoor ink includes: $\pu{25 g}$ of solvent blue 70. $\pu{25 g}$ of nigrosene. $\pu{??? g}$ of silver nitrate in a denatured alcohol base. Several "...
0 votes
0 answers
29 views

Does manganese dioxide disperse differently in bases than in water?

As part of a project in uni I've been given a task in my chemistry laboratory to synthesise manganese dioxide powders. I prepared a precipitate of it by reacting manganese chloride with sodium ...
1 vote
0 answers
28 views

Surface treatment and current density: electrodeposition of Cd and Ag

I'm currently working on a cadmium and silver electrodeposition project. Let me explain: I'm doing electrolytic surface treatment on low-alloy steels as well as stainless steels. At present, we have ...
-1 votes
1 answer
60 views

What precipitate forms when adding aqueous sodium sulfate solution to an unknown white solid?

I don't understand why there aren't two solutions to the following problem: You are presented with a white solid and told that due to careless labeling it is not clear if the substance is barium ...

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