Questions tagged [density]

For questions involving (theoretical or experimental) comparison of density of elements or substances, calculating density of solutions, effects of temperature on density, and other chemical aspects of density.

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How do water vapor molecules push other air molecules away?

I've read that when water vapor enters the atmosphere, the vapor molecules push the oxygen and nitrogen molecules out of the way and occupy their space. But if water vapor molecules are lighter than ...
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How molarity and mass fraction are related? [closed]

Concentrated sulfuric acid contains very little water, only $5\,\%$ by mass. It has a density of $\pu{1.84 g mL-1}$. What is the molarity of this acid? I know to use the molarity $c$ is in $\pu{mol L^...
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Why is Molar Mass of a gas twice the vapour density?

I've seen this relation at a number of places, and I can't get why. A simple Google search doesn't give me a simple answer either. Also, are there any exceptions/conditions for this relation to be ...
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COSMO Segment charge density via NWChem [closed]

I'm struggling to get COSMO segment surface charge densities that I need to create the sigma profiles in COSMO-SAC. I am not a chemist by training, so please explain like I am five. I've read papers ...
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-3 votes
1 answer
133 views

Why are certain gases with higher molar masses less dense than the ones that have a lower one?

Neon, despite having a larger molar mass than nitrogen, oxygen and fluorine, is less dense than all of them. This also goes that fluorine (again) and chlorine are both denser than argon, even though ...
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-6 votes
1 answer
56 views

Can someone explain this answer in detail? [closed]

The density of iron is $\pu{7.874 g/cm3}$ and its unit cell volume is $\pu{2.364E-23 cm3}$. These values indicate that there are: two Fe atoms per unit cell and the metal is body-centered cubic. I am ...
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Saturated vapor and liquid densities (VLC curve) from Helmholtz free energy equation of state

I have been reading about the statistical associating fluid theory (SAFT) which computes the Helmholtz free energy ($A$) from the SAFT EoS (a hell lot of equations) for a molecule of interest, and is ...
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1 answer
51 views

Is the density of a mixture ever just the sum of the densities of each species in the mixture? [closed]

My current hypothesis is that this is true when the volume is finite and perhaps this would cause the densities to be additive. For example, imagine there is a closed container, 2 L in size. And ...
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3 votes
4 answers
149 views

A dense solute for oils that's easy to acquire

I'm working on a crafts project that is basically putting oil, water and glue in a bottle together with glitter just so you look at it. I want to see how it looks if the density of the oil is very ...
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Current density from overpotential

A current of $190$ mA is measure for a $2.5$ cm$^2$ electrode in contact with a solution containing M$^{2+}$/M$^{3+}$ metal ions at room temperature at a overpotential of +$180$mV. The transfer ...
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Water density in the calculation of the ionic product of water

In 2019 the International Association for the Properties of Water and Steam released this document for the semi-empirical calculation of the ionization constant of water: http://www.iapws.org/relguide/...
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Compare density of halogen substituted benzene rings

The correct decreasing order of densities of the following compounds is : (1) (D) > (C) > (B) > (A) (2) (C) > (D) > (A) > (B) (3) (C) > (B) > (A) > (D) (4) (A) > (B) >...
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Density and partial pressure [closed]

A sample of $\ce{NOBr}$ gas was placed in a rigid flask where it decomposes at $\pu{25 ^\circ C}$ according to the following reaction: $$\ce{2NOBr(g) <=> 2NO(g) + Br2(g)}$$ At equilibrium, the ...
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Heat released at constant pressure and temperature and heat released at constant density and temperature

Is there a relation between heat released at constant pressure and temperature and heat released at constant density and temperature? I was reading some books on propulsion and combustion, and the ...
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6 votes
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Why is potassium less dense than sodium?

Potassium has a density of $\pu{0.86g/cm3}$ and sodium has a density of $\pu{0.97g/cm3}$,even though potassium is below sodium and one might expect the alkali metals to exhibit monotonously increasing ...
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1 vote
1 answer
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Density and Viscosity for Solution: 80% Liquid Methane CH4 with Solution of 20% Gas Nitrogen N2 on Surface of Titan (the largest moon of Saturn)?

Problem: Need to estimate the density and dynamic viscosity of such a mixed fluid: 80% Liquid Methane CH4 with solution of 20% Nitrogen Gas N2 with temperature of 94K and pressure of 1,467 hPa (the ...
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4 votes
2 answers
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Relationship between molar mass and density in solids

In ideal gases, it's pretty clear that 1 mole of gas occupies 22.4 L at STP. By knowing this, it's easy to calculate density given molar mass. However, this isn't true for solids. If I know molar mass ...
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18 votes
2 answers
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Why does a 57.15% ABV spirit (ethanol+water) have a density of 923 kg per cubic meter?

According to the UK proof standard, a 100 proof spirit was defined as a spirit with gravity of $\frac{12}{13}$ that of water or $\pu{923 kg m-3}$, which is equivalent to $\mathrm{57.15\% \ ABV}$. One ...
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1 answer
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What factors other than atomic weight affect density of an element? [closed]

Iron, for example, has an atomic weight of 55.845 Whereas hydrogen's atomic weight is 1.008, 1.8% of Irons. And the density of Hydrogen (at STP) is 0.0899 g/L, 1.14% of of Iron's density of 7.874 g/...
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1 answer
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Air bubbles in water [closed]

Problem : Gas. Density. (Composition) N2- 0.879 (0.78) O2-. 1.32 (0.21) Why air bubbles don't disintegrate in water into different components due to difference in apparent weight (= ...
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When calculating the distance between molecules in a solution, is it reasonable to approximate a sphere around each molecule? [closed]

I am attempting to calculate the average distance between molecules in a particular concentration of a solution. My first instinct was to treat the solution as a system of spheres surrounding the ...
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0 votes
1 answer
585 views

Preparing aqueous solution of ethanol [closed]

You need to prepare $\pu{250.0 mL}$ of an aqueous solution of ethanol in the concentration will be $\pu{0.500 mol L-1}$. You have $\pu{100 mL}$ of a commercial solution of ethanol in water $(35.0\% \,...
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8 votes
2 answers
3k views

Density range of table salt?

Does anyone have a reference for the density range of common table salt $(\ce{NaCl})?$ A pure $\ce{NaCl}$ crystal has a density of $\pu{2.16 g/cm^3}.$ However, the salt granules in table salt don't ...
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3 votes
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What are the least dense fluids?

This question left me wondering what other very light (condensed) fluids could exist, at any environmental condition. Obvious candidates for the list are (at their Bp./1 bar) LH2 (0.07 g/ml) LHe (0....
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What is the density of sodium trimethylsilylpropanesulfonate (DSS)?

I tried to look for the density of sodium trimethylsilylpropanesulfonate (DSS) online but could not find anything. Perhaps someone here measured it/knows where it may be found?
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1 answer
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Calculate molarity given density and mass percentage [closed]

Problem Calculate molarity of a solution of $\ce{H2SO4}$ with density $\pu{1.198 g/cm3}$ and containing $27~\%$ mass of $\ce{H2SO4}.$ Answer My approach I converted the density to g/l. Then i took ...
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7 votes
1 answer
923 views

Is the density of a two-component mixture always between the densities of its individual components?

There exist eutectic mixtures, in which the freezing point of the mixture is below those of either component of the mixture, i.e., the freezing point of the mixture is not intermediate between that of ...
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2 votes
1 answer
84 views

How do I figure out the composition of a material given specific densities?

The Problem A waste material consists of sand (SG 2.7), a chemical salt (SG 2.1), and a dense plastic (SG 1.4). 200 g of a representative sample from the material is found to have a density of 2300 kg/...
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Moles of chlorine gas needed to make up an equivalent amount of saturated salt solution

I’m trying to solve a question about a saturated salt solution but am unsure of how to answer one of the parts or what it’s asking for. The Problem The maximum solubility of table salt (NaCl) in water ...
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3 answers
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Volume calculation perchloric acid 70%

HClO4= 100.5, d HClO4=1.8, (ACO)2O=102, d (ACO)2O=1.1, H2O=18, d H2O=1 A) Preparation of 100 ml perchloric acid 0.1 Molar aqueous solution. below is my answer, but what I'm not sure is that the ...
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5 votes
1 answer
883 views

Why is platinum denser than gold?

The atomic masses of gold and platinum are 196.96657 u and 195.084 u respectively, meaning that (on average) an individual gold atom is heavier than an individual platinum atom. At the same time, the ...
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6 votes
2 answers
370 views

What makes some chemicals form steep density gradients in solution?

Caesium chloride and sucrose are both suitable for isopycnic centrifugation, and presumably not much else is. I'm unclear as to the mechanism by which they form useful density gradients. Wikipedia ...
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Largest change in the water level [closed]

Which would produce the largest change in the $\ce{H2O}$ level when added to water in a $\pu{25 mL}$ graduated cylinder? (A) $\pu{10.0 g}$ of $\ce{Hg}$ $(d = \pu{13.6 g/mL})$ (B) $\pu{7.42 g}$ of $\ce{...
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1 vote
0 answers
65 views

Suspension liquid for ferrofluid that makes it float [closed]

I am currently devising a project to create a kinetic sculpture, similar to Sachiko Kodama. Does anyone know any suspension liquids that when applied, the ferrofluid floats on top?
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2 votes
1 answer
141 views

Density of water increases from 273 to 277 K due to increase in entropy?

In a set of questions that I was solving, the answer to one of the questions asking why the density of liquid water increases from 0 to 4 degrees C had the above answer: due to an increase in entropy. ...
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0 answers
59 views

Theoretically predict the density of water

Is it possible to predict the density of water having just its molecular structure (basically obtain 1 g/cm3 at 3.96 °C)? Are you aware of research/textbook that dive into this topic? Is it able to ...
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3 votes
0 answers
45 views

What gas would be suited best to form a density gradient in a long tube? [closed]

I want to set up an aero-optics experiment using a sealed ~5 m length of pipe with a gas inside. The gas must form a density gradient, and must be transparent enough to view a target at the other end ...
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2 votes
1 answer
155 views

Separation of methanol–water mix in a plate distillation column

I conducted an experiment to separate methanol and water. I am trying to determine the mole fraction of the distillate collected but having a little trouble with the calculation. The flow rate was $\...
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Why are the OV and VO blocks of the CIS 1RDM zero?

I know the reduced density matrix has the form: $$ \gamma(\alpha,\beta) = \langle\Psi_N|c^{\dagger}_{\alpha} c_{\beta}|\Psi_n \rangle $$ but when $\Psi_N$ is the configuration interaction singles (CIS)...
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1 vote
0 answers
224 views

Predicting atomic weight and density of calcium [closed]

I have a question from school: Assuming that the element Ca had not been discovered, predict using the properties of the known element surrounding Ca its own properties such as its atomic weight ...
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0 votes
2 answers
385 views

Density and concentration of hydroiodic acid [closed]

I weighted my hydroiodic acid sample: 25 ml weight 34.1 g, so the density is about 1.364 g/ml. I want to know its concentration based on density. Does anyone have the corresponding density chart?
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1 answer
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Most dense hydrogen containing composition [closed]

I am searching for a composition which could host the most hydrogen atoms in a specific volume. Note that this density is sought for justifiable conditions in terms of pressure, temperature, ... and ...
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1 vote
0 answers
233 views

Over time what happens to soluble liquids with different densities

I have a case with two liquids: Water and another chemical which is miscible in water. The chemical has a density of 800 g/l so it's 20% less dense than water. Initially the chemical was mixed with ...
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1 vote
0 answers
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Two common fluids that don't mix inside a labyrinth [closed]

I'm not sure in which SE site put this question. Imagine a typical child toy, where a bunch of spheres move by gravity through a labyrinth. Now imagine a sealed small labyrinth with two fluids. I'd ...
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1 answer
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What Value of Purity Do We Substitute in the Formula C=10PD/M

In the the formula $$C = 10P\frac{D}{M}$$ $C$ is the concentration of a substance in a solution, $P$ is the percent concentration (purity) of the substance, $D$ is the relative density of the ...
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1 answer
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Sample: How to calculate mass of nanopaticles with given density and Vol % [closed]

I'm trying to calculate the wt% and the mass of the nanoparticles in a ferrofluid solution. Attached is data from the supplier: ...
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1 vote
2 answers
490 views

How to reduce surface tension of oil?

I would like to create tiny colored drops slowly falling down in a transparent liquid. The diameter of the droplets must be around 2mm, and their speed must be approximately 0.5 mm / sec. For that, ...
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19 votes
2 answers
7k views

What is the least dense liquid under normal conditions?

What is the least dense liquid under normal conditions, room temperature, one atmosphere of pressure, doesn't combust upon contact with air, also wouldn't kill a human just for being in the same room ...
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1 vote
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Calculating Air Density and Effect of Air Composition

I have to calculate density of atmosphere, assuming that it is: 79% : N2 21% : O2 Does the percentage of gases affect the answer, and how can we find the density with such little information?
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-5 votes
1 answer
347 views

Does iron nail sink in rubbing alcohol [closed]

I have been trying for so long to get answer
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