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Questions tagged [equipment]

Questions regarding the equipment used in labs (such as flasks, tubes etc.), their operation and maintenance.

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Why are amber bottles used to store Water for HPLC?

Image Source: https://www.calpaclab.com/water-hplc-spectro-grade-4-liter-bottles-case-4/ted-ws2211-001 When ordering HPLC/Spectro grade Water for HPLC from certain vendors(not all), it comes in an ...
Ronith's user avatar
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1 vote
0 answers
64 views

The accurate use of a "Mortar and Pestle" and its grinding patterns

At my internship, I was asked to use a mortar and pestle. I placed a pigment sample in the mortar, and was asked to apply a downward pushing motion in a circular pattern with my pestle. I kept a firm ...
Ronith's user avatar
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5 votes
2 answers
583 views

What does the blue square on a volumetric flask mean?

What does this blue square on my volumetric flask mean? I see such squares/rectangles on a numerous other flask brands as well. What is its purpose?
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5 votes
2 answers
227 views

Why don't oils use plastic droppers?

As shown in the picture, most cosmetic oils and serums make use of glass droppers. However in the chemistry lab, scientists often also use reusable plastic droppers as well. My question was that, ...
Ronith's user avatar
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7 votes
1 answer
955 views

What do double rings mean on a pipette?

In this image of a pipette, what do the double rings mean?
Paul Jones's user avatar
2 votes
0 answers
39 views

What is this gel byproduct of acetylsalicylic acid recrystallization?

I did a very simple acetylsalicylic acid synthesis from salicylic acid and acetic anhydride (with phosphoric acid as a catalyst). After rinsing, filtering and drying the product I dissolved it in ...
Thomas's user avatar
  • 31
0 votes
1 answer
147 views

When Should you use grease to lubricate ground glass joints?

I am getting ready to try steam distillation following this guide which references an earlier chapter which says "If using grease as recommended by your instructor, lightly grease all joints.&...
hildred's user avatar
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-2 votes
1 answer
93 views

Why potassium carbonate breaks glass when heated? [closed]

I have been studying about desiccants for a while and testing some inorganic salts, including calcium chloride, sodium sulfate and potassium carbonate. When they get enough moisture from air, I ...
Clinfosfito's user avatar
3 votes
1 answer
366 views

How can I read an Anschütz/Bennert manometer and how can I make sense of it?

Recently I have come across a mercury-filled manometer for vacuum distillation that somewhat resembles a U-tube shaped manometer, but with one arm sealed and completely filled with mercury. Searching ...
Fractal's user avatar
  • 402
2 votes
1 answer
57 views

Is it critical to match vacuum pump oil to specific pump?

We have rotary vane vacuum pumps of many makes, models, and ages, but superficially they seem remarkably similar. Each has a recommended pump oil (that is, if we can find the documentation); often ...
ike9898's user avatar
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5 votes
0 answers
269 views

Why does glass etching cream contain sulfuric acid?

The MSDS for various glass etching creams all show that they're primarily composed of 4 substances (the composition percentages vary): Ammonium Bifluoride - 20 - 40% Sodium Bifluoride - 5 - 10% ...
Necoras's user avatar
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17 votes
1 answer
2k views

What's the purpose of this vintage glassware?

I found this glassware in a phytochemistry lab abandoned in the 1990ies. The piece itself was shelved in the storage room, thus probably already obsolete back then. The device, entirely glass, is a ...
I_O 's user avatar
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0 votes
0 answers
74 views

Using a vintage lab balance scale with a chain-dial

I have obtained an an antique Philip Harris balance scale in good, but condition aside from a lot of corrosion on the brass. I can't find a model number on it and am not sure of it's actual age, but I ...
Troy Peterson's user avatar
1 vote
0 answers
46 views

What is the sample density used for a buoyancy mass correction?

For a lab exercise to calibrate volumetric glassware I was given the follow equation to correct weighings for the density of air: $$m_\mathrm{c} = m_\mathrm{s}\,\frac{1 - \rho_\mathrm{a}/\rho_\mathrm{...
Steve Dutky's user avatar
1 vote
0 answers
337 views

Can I use a mechanical pipette to transfer strong acid?

I am an undergraduate student majoring in physics. I am looking for the best method to accurately measure the volume of strong acids like hydrobromic $(w(\ce{HBr(aq)}) = 48\,\%)$ and hydroiodic $(w(\...
gagagaga's user avatar
2 votes
1 answer
240 views

Is Silica Gel fit for Ultra-High Dessication?

I had the (perhaps wrong) notion that silica gel wasn't that strong of a dessicant, especially compared to CaO, MgO, CaSO4, H2SO4, KOH, Mg(ClO4)2), but I've been exposed to information* that might ...
Hans's user avatar
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0 votes
0 answers
84 views

Would a 0.3 micron filter be effective in blocking formaldehyde fumes produced by curing cyanoacrylate?

I’m looking into purchasing a mask that blocks particles larger than or equal to 0.3 μm in size. I’m hoping it blocks the formaldehyde fumes produced by curing cyanoacrylate. How effective such mask ...
user642965's user avatar
14 votes
1 answer
609 views

Why do Büchner funnels have no glaze on the top rim?

I have a question about Büchner funnels (just out of pure curiosity). The funnels I have seen have no glaze on the top rim. Actually, the question is why the top end is not glazed. Does it have any ...
Istrel's user avatar
  • 251
3 votes
0 answers
734 views

Which vessel materials are compatable with magnetic stirrers?

I am shopping for some metal pans and beakers for use on my magnetic stirring hotplate. I do not want to block the magnetic coupling of the stir bar. The question is which common alloys are compatible?...
Max Power's user avatar
  • 207
2 votes
0 answers
92 views

Connect glass tubes to a graham condenser

I am currently making a syphon coffee maker such as this one: However, I find that all the silicon tubing used on this image between the condenser and the boiling flask / between the condenser and ...
Hugosh's user avatar
  • 41
0 votes
1 answer
296 views

Experimental setup

I would like to know your opinion regarding the setup of a system for oxygen purging with nitrogen. Before ordering the necessary materials, I'd like to be sure if this setup is feasible or if it can ...
Emmcrumun's user avatar
4 votes
1 answer
2k views

How should you report measurements and uncertainty for a measuring cylinder with 0.5 mL graduations?

I understand that a common convention is to report the uncertainty of an analogue instrument as plus or minus half of the smallest scale division. By this logic, a measuring cylinder with $\pu{0.5 mL}$...
Vandelay's user avatar
  • 135
0 votes
0 answers
48 views

What material should my evaporation dishes be made of to combat static charge buildup?

I have great difficulties moving very fine powders from a drying dish (glass) into small plastic containers using a metallic spatula due static charging. I have to scratch a lot inside the glass ...
And's user avatar
  • 238
2 votes
0 answers
52 views

Best bet for separating fused glassware

I have a sintered glass funnel stuck in a flask with a 24/40 ground glass joint. I regularly used this glassware to process very dilute solutions of uncured photopolymer resin dissolved in ethanol. ...
Jason C's user avatar
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6 votes
2 answers
4k views

Which is a more accurate scale for a chemistry high school lab - a triple beam balance or a digital balance and why?

I would like to ask the experts of this chemistry community their opinions on which balance is more accurate and effective to use in a high school chemistry lab- a triple beam balance or a digital ...
suse's user avatar
  • 803
6 votes
2 answers
835 views

Is there a simple way to distinguish grades of purity for copper metal?

Is there a simple way to distinguish different grades of fine copper purity (on a trace metal basis) that can be carried out in a small lab? Specifically, I would like to be able to differentiate 4N, ...
Hans's user avatar
  • 1,097
0 votes
2 answers
157 views

Can stainless steel be electrically insulated with (oven-dried) Sodium Silicate Solution?

Can I electrically insulate stainless steel by painting Sodium Silicate solution on it and heating it to 200C for 30min or so? The solution should be conductive, and I've been told (to be verified) ...
Hans's user avatar
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1 vote
1 answer
223 views

Will Sodium Polyacrylate (SAP) absorb the gas from liquid ammonia?

I'm considering using sodium polyacrylate grains to absorb spills of a relatively strong Ammonium Hydroxide solution. Will the SAP (super absorbent polymer) only absorb the water, and in effect make ...
Kendall Seymour's user avatar
1 vote
1 answer
48 views

Microfiltration for saturated solutions of highly hygroscopic compounds?

Is it possible to pass saturated solutions of compounds with very high solubility through filters with small pores (e.g. passing a saturated aqueous ZnCl2 solution at 90C through a 2mcm glassfiber ...
Hans's user avatar
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1 vote
1 answer
101 views

Does adding NH3 to an HCl solution facilitate the dissolution of aluminum compounds?

If we compare the two solutions hereafter, which one would better leach/dissolve aluminum metal/compounds present at/near the inner surface of the glass: Solution A: $10\,\%\, \ce{HCl + H2O}$ Solution ...
Hans's user avatar
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2 votes
0 answers
94 views

Appropriate ways to remove aluminum from the surface of glass?

I'm looking for a way to treat the surface of borosilicate glassware such that it won't contaminate solutions of puriss reagents in conditions that pure $\ce{SiO2}$ wouldn't, yet keep the bulk ...
Hans's user avatar
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2 votes
1 answer
127 views

Trial by fire: Safely heating sand without it agglomerating?

Wikipidia quotes a melting point of 1713C for sand. I went on the beach to get some sand. I assume it's a mix of all kinds of stuff. The finality is to prepare a big pile of clean sand to use as ...
Hans's user avatar
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4 votes
1 answer
76 views

How does functionalized activated charcoal work?

If I understand correctly it is possible to trap stuff inside activated charcoal (AC) pores to give it specific retention properties (by exposing it to functionalizing compounds while heated to open ...
Hans's user avatar
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2 votes
1 answer
790 views

Can I engrave borosilicate glassware without compromising its structural integrity?

Can I use a pen engraver (the kind that's like a tattoo gun with a diamond tip) to engrave my initials on labware without compromising it? I am in a lab space with a shared acid wash, and my glassware ...
user278411's user avatar
10 votes
3 answers
5k views

Is it better to use a smaller, more accurate measuring cylinder several times or a larger, less accurate one for the same volume?

I need to measure out 70 ml of liquid. I have a 10 ml measuring cylinder with a maximum uncertainty of 0.1 ml and a 100 ml measuring cylinder with a maximum uncertainty of 1 ml. I've calculated that ...
John Johnson's user avatar
7 votes
2 answers
10k views

How to identify a blow-out pipette?

Is my pipette a blow-out pipette? I suspect that it is a blow-out pipette, though the double lines aren't rings. My guess is it is a TC blow-out pipette. It's a big 50 mL pipette, longer than my arm. ...
user1095108's user avatar
8 votes
1 answer
265 views

What is the purpose of this glassware?

I have seen these small test tube looking doohickeys being supplied from many chinese suppliers, but never with any description as to what they are for. They almost invariably have the description &...
TWiz's user avatar
  • 247
2 votes
0 answers
122 views

Does mercury react with polycarbonate?

Looking around at various material compatibility charts, they seem quite divided on the compatibility of metallic mercury and polycarbonate. Some sources (here, here, or here) indicate that ...
loudaslife's user avatar
0 votes
0 answers
691 views

What is the product of ammonia reacting with silicone?

I used a soft silicone hose to carry ammonia at ~70 °C. I was surprised to later find the hose had hardened. A quick materials compatibility search for silicone had given me a lot of info but an "...
Hans's user avatar
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1 vote
0 answers
50 views

HDPE vs PP for storing pure aldehydes

I know both HDPE and PP have at least some degree of resistance to aldehydes, esters and aliphatic hydrocarbons. I am concerned however about minute contamination over time of pure samples and so I ...
Hans's user avatar
  • 1,097
-1 votes
1 answer
89 views

Any plastic for long term storage of Puriss. Ethanol?

I'm being offered to share some puriss Ethanol. Can I store it long term in any plastic container without the slightest contamination/reaction from the plastic? I have HDPE, PET, but I could buy ...
Hans's user avatar
  • 1,097
5 votes
1 answer
1k views

Safest way to conduct a reaction with bromine under reflux conditions

I am conducting an electrophilic aromatic bromination reaction according to literature. The substrate and intended substitution pattern do not matter, but the reported procedure requires the dropwise ...
Jan's user avatar
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0 votes
1 answer
167 views

Reduction by Activated Carbon

Does reduction by carbon itself occur when filtration is performed using activated carbon? Is it part of the central mechanisms involved in activated carbon filtration? One of the specificities of all ...
Hans's user avatar
  • 1,097
1 vote
1 answer
182 views

Experience with PTFE tubing & glass connectors?

I'm wondering which PTFE tubing size to get to connect to normal 10mm OD glass connectors. For a silicon hose I would take an ID of 8-9mm as it is flexible but I think PTFE is quite rigid. Anyone has ...
Hans's user avatar
  • 1,097
2 votes
0 answers
128 views

What has happened with the pH-meter?

The glass sensor has became red inside like something melted. I stored it in a liquid with pH that mentioned in the manual. What is that and why could that happen, how often that happens with pH-...
R S's user avatar
  • 315
11 votes
3 answers
3k views

Sintered vs perforated plate Büchner funnels

I just bought a sintered-glass style Büchner funnel for some vacuum filtration tasks. There's two issues I'm having with it: Filter material, especially activated charcoal, ends up stuck in the glass ...
Jason C's user avatar
  • 1,172
1 vote
1 answer
2k views

when using glass to glass stoppers, is it best to have them dry or use lubricant?

I have some glass flasks that have glass stoppers. It’s basically the typical glass stopper with the frosted tip which fits into a glass opening. Basically think of a typical glass volumetric flask. i ...
Ryan Pelich's user avatar
0 votes
0 answers
28 views

Affordable, non-contaminating flexible tubing for common acids

Which tubing material is affordable, flexible, widely available, and suited for transporting very pure acids ("puriss." products) in their most concentrated form without contaminating them? ...
Hans's user avatar
  • 1,097
8 votes
1 answer
1k views

What kind of filter can remove zeolite dust from ethanol?

I only really have high school level knowledge of chemistry, and also I don't really own any lab equipment. I'm using 3A zeolite molecular sieves to dry ethanol (and sometimes isopropanol) and they ...
Jason C's user avatar
  • 1,172
1 vote
0 answers
73 views

Is the width of a Soxhlet Condenser Inherent to its Function?

Soxhlet extractors are often coupled to a specifically designed condenser with a very large lower joint. Is this inherent to it's function as a condenser in the apparatus or only because the Soxhlet ...
Hans's user avatar
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