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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1answer
52 views

Understanding the setup of a chemistry lab about redox

In chemistry lab we were looking at oxidation and reduction reactions. To determine the relative activity of several metals we observed reactions between the metals and aqueous solutions of dissolved ...
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24 views

how does mass of carbon 12 is like this? [duplicate]

1u is defined as per carbon 12 so 1 atom of c have 6 neutrons and 6 protons both having mass more than 1u (Google)so total mass of carbon 12 is more then 12u (also there would be some mass of ...
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48 views

How to confirm a powder is Sodium Hydroxide?

Long-story-short, my mother found a bag of white powder with some soap making supplies. We're about 90% sure it's powdered lye, but I thought it would be fun to confirm this somehow. Is there a way ...
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39 views

Steps of crystallization

An excess of copper(II) oxide is added to dilute sulfuric acid to make crystals of hydrated copper(II) sulfate. The processes listed may be used to obtain crystals of hydrated copper(II) sulfate. ...
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3answers
245 views

Why isn't my galvanic cell making enough voltage?

I'm in kind of a pickle here. I made a galvanic cell of Lead and aluminium for a chemistry internal assessment but unfortunately, it didn't turn out so well and neither me nor my teacher has any clue ...
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1answer
216 views

How to standardise NaOH? [closed]

My aim is to "To determine the concentration of citric acid in lemon juice using titration technique." and as following i need to standardise the NaOH in order to titrate it with validity. Is there a ...
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63 views

Why do we begin an experiment involving solutions of different concentration from the least concentrated solution?

Is there a particular benefit to start any kind of measurement with the least concentrated solution and then work my way up to the more concentrated solution? In one of my experiment, we measure the ...
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1answer
82 views

How to keep raspberry ketone from forming crystals again after dissolving in alcohol?

I dissolved raspberry ketone 700 mg in 10 ml of 99% isopropyl alcohol. The solubility according to pub chem is 1 g/ml. After dissolving, I added room temperature water to bring the final volume to 70 ...
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2answers
543 views

If magnesium reacts with oxygen to produce magnesium oxide only on the application of heat, then why isn't it categorised as an endothermic reaction?

Why isn't the energy that is used to overcome the activation energy of magnesium metal atoms to react with oxygen, not taken into account?
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1answer
34 views

How to quickly diffuse a dye through still water

I'm doing an engineering experiment soon and would like to be able to quickly dye water. The water is still (i.e. not moving) and I would prefer not to physically disturb the water as best I can. ...
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1answer
134 views

Grignard reaction on electron-poor benzyl bromides

I am trying to prepare a Grignard reagent from 4-nitrobenzyl bromide but the reaction just doesn't work. My conditions are: 10 mL of THF (anhydrous); 7.04 mmol of 4-nitrobenzyl bromide; 7.04 mmol of ...
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2answers
166 views

At what position in the distillation apparatus does the temperature match the boiling point of the distilled substance?

A student is separating $\ce{CHCl3}$ (bp = $\pu{61 ^{\circ}C}$) from $\ce{CHCl2CHCl2}$ (bp = $\pu{146 ^{\circ}C}$) by distillation. She has just begun to collect the first distillate in the receiving ...
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0answers
19 views

Is the iodide and persulfate reaction bimolecular?

Given the following reaction in an aqueous state: $$ \mathrm{2I^- + S_2O_8^{-2}\rightarrow I_2 + 2SO_4^{2-}}$$ Is it bimolecular o trimolecular? Because two molecules of iodide react with one ...
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1answer
17 views

Calculating the Presence of Anthocyanin in a Solution [closed]

I've produced a red cabbage solution (boiling red cabbage in water basically), and would like to calculate the concentration of the red cabbage/anthocyanin in the solution. How is this accomplished? ...
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0answers
45 views

Pyrophoric nature of Raney Nickel

I am about to do a hydrogenation lab, and a, struggling with how to prepare my Raney Nickel so it does not spontaneously ignite during my lab. Most websites say to just submerge it in water– is this ...
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1answer
71 views

how to calculate the initial concentration of NaOH in a mixture? [closed]

I have doubts about how to find the equation for the calculation of the initial concentration of $\ce{NaOH}$. I have the following information: in the kinetic study of a reaction, We measure $\ce{20....
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1answer
398 views

Why does the colour of gold sol change with particle size? [duplicate]

Regarding the colour of gold sol, my book says Finest gold sol is red in colour; as the size of particles increases, it appears purple, then blue and finally golden. This is the image I found on ...
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2answers
200 views

No current in homemade galvanic cell

I built a galvanic cell using 0.01 M solutions of copper sulfate and zinc sulfate. I used copper and zinc electrodes and immersed them into the proper solutions (copper into copper sulfate, zinc into ...
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24 views

How does hydrated salt lose water?

Hydrated salt—-> anhydrous salt How do I determine the temperature and time needed to turn all the water to steam?
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1answer
42 views

XAS spectroscopy - Differences in magnitude of 2p SOC and 3d SOC?

Within L-edge x-ray absorption spectroscopy, the spin-orbit coupling within the 2p shell results in the splitting of the L edge into L3 and L2 edges.As given in the following paper http://dx.doi.org/...
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1answer
100 views

How to determine Acid-Base Indicator [closed]

How do we determine which is the best indicator to use when given the initial pH’s of both the acids and bases and the endpoint value of our base?
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0answers
41 views

Developing a lab to identify the concentration of casein in organic milk

I am currently attempting to create a feasible lab design that will enable me to identify the concentration of casein protein in organic milk without having to use spectroscopy. Thus far I have ...
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2answers
165 views

Is there a replacement for glacial acetic acid in determining peroxide value

I am not allowed to use glacial acetic acid at my school, which all procedures online for finding the peroxide value of oils use through an iodometric titration. Is there a replacement?
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1answer
64 views

Is it more precise to measure a substance as a solid or as a liquid?

If I have a substance and want to obtain an exact quantity of it, is it better to measure it as a solid or as a liquid? In other words, if I have, for example, NaCl crystals I can weigh the crystals ...
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2answers
347 views

What does the reaction of hydrogen and iodine to hydrogen iodide look like?

The reaction, $\ce{H2 + I2 <=> HI}$ is often used as an example for equilibrium reactions. It is however a difficult reaction to show in a school laboratory: we are not equipped to work with ...
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2answers
118 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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1answer
124 views

How can I Identify Elements in Objects? [closed]

Since all objects on earth are composed of elements, how can I identify the fundamental make-up of objects such as trees, glass, bricks, wood, plastic, shoes, and other entitys?
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1answer
47 views

How can I prevent my spin-coated silica thin film from cracking when I heat it up?

I am spin-coating a porous silica solution on a glass microscope coverslip, and then heating the resulting thin film to $\pu{350 °C}$, in an attempt to create a thin film of porous silica sol gel. I ...
2
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1answer
61 views

Simple alternative to UNIFAC to prove that a mixture containing 1ml of x and 5 litres of propylene glycol is not flammable?

Section 2.6.1 of the REGULATION (EC) No 1272/2008 (CLP) defines a flammable liquid as: Flammable liquid means a liquid having a flash point of not more than $60 ^{\circ}$C. So data on flash ...
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2answers
71 views

Precipitation of AgCl from the tap water solution of the group 2 chloride

I had this question about an experiment where the group 2 chloride was dissolved in distilled water and excess $\ce{AgNO3}$ was added to the solution to form $\ce{AgCl}$ precipitate. One of the sub-...
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1answer
56 views

Which reactions occur during the oxidation and dissolution of bromide/bromine?

I'm trying to understand the fate of bromide anions during and after they undergo anodic oxidation. I have a solution of 94% DMF/6% water (by volume) with 0.1 M tetrabutylammonium bromide (TBAB) as ...
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1answer
136 views

Applications of magnesium sulfate monohydrate MgSO4 · H2O

How is magnesium sulfate monohydrate $\ce{MgSO4 * H2O}$ used for in chemistry and how does it work as a valuable laboratory drying agent? I could not find too much information in my book or the ...
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1answer
38 views

How to measure UV index? [closed]

I am a high school student so please apologise if I say something very dumb or irrelevant. I am conducting an experiment in which I want to find UV index at different points. Such as under shade, ...
2
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1answer
112 views

Is it considered safe to sonicate with flammable solvents?

I use a sonicator at work in a cleaning process. It involves sonicating acetone, NMP, and IPA. We would like to move forward with other flammables as well. We currently do the work in a hood, but no ...
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1answer
77 views

Is it possible to make polyethylene in a high school laboratory?

We learned how to make small amounts of ethene from ethanol using sulfuric acid. Is there a way to make a visible amount of polyethylene from that using materials I could get for a school lab? We can'...
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1answer
27 views

How much drinking water can I get back [closed]

If I was to boil a gallon of sea water and collect the condensation, how much drinking water would I get back?
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1answer
2k views

What's this glassware?

Can anybody tell me what this glassware with a stem, bulb and long tube is?
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1answer
212 views

How can I use a solvent gradient in column chromatography? [closed]

I am working to use the column, there are a lot of videos which explain it, but I don't understand this statement in the procedure. The residue was finally purified by column chromatography using ...
3
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2answers
953 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 $...
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1answer
176 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 ...
11
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1answer
3k views

What is the role of ammonium chloride in the workup of a Grignard reaction?

In the following Grignard reaction, why is aqueous ammonium chloride used to get to the products? I don't see how it participated in or modified the reaction from what is normally expected.
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3answers
96 views

How Can I Induce Corrosion Electrochemically?

I'm very interested in measuring corrosion in metal alloys, particularly in salt solutions. I understand metals corrode over time, however, I was wondering if it's possible to electrochemically "speed ...
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1answer
356 views

How do I make a 0.5 M citrate buffer at pH 4.5?

I need to make a citrate-sodium citrate buffer at 0.5 M concentration and pH 4.5. I calculated the molarities of the citrate and disodium citrate based on the Henderson Hasselbalch equation, using a p�...
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1answer
471 views

Can an iodine clock reaction work without using a strong acid?

I'm going to do an iodine clock reaction for a project and we had to submit the materials and safety sheets for the experiment a while ago. I thought I could do one by using hydrogen peroxide, sodium ...
2
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1answer
580 views

How to effectively wash the precipitate or crystals on the filter and why?

My lab manual says that the precipitation on filter should be washed with a few small portions of the washing liquid. Why can't I just completely fill the filter funnel with the solvent instead of ...
2
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1answer
50 views

vapor pressure of one part of binary compound

Let's say we have a binary compound AB in an enclosed container, and let's say there's a tendency to form B-vacancies so that B atoms/molecules escape and form a vapor. Let's assume there's enough of ...
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29 views

Metal colored flame and safety

For Chrismtas I was a given a wonderful gas lighter, that produced a pink flame by heating small metal pads (when the pads are cold, the flame is blue, once they are red hot, the flame is colored). ...
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1answer
157 views

Hydrogenation of 1-hexene with Raney nickel

For my high school senior chemistry project, I need to create and perform a lab. I've chosen to do the hydrogenation of 1-hexene with the catalyst of Raney nickel. I'm struggling because I'm not ...
5
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3answers
138 views

Changes in pH when adding substances other than acids or bases

If I start out with 100 mM acetic acid, what substance (to a final concentration of 1 M) could I add to change the pH considerably? I was thinking of NaCl or ethanol or acetone. Substances added ...
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1answer
33 views

Suitable safe cleaning solution for aliphatic urethane

I am looking for a suitable cleaning solution for a sprayed on coating that is an acrylic aliphatic urethane. My end goal would ideally be something that can neutralize rust, whiten and brighten the ...