Molecules Definition and 543 Threads

There is the atmosphere that is composed of 4 parts: the troposphere, the stratosphere, the mesosphere, and the thermosphere. I know that air is a gas made up of molecules. And a gas fills up the container it is contained in, which is the atmosphere. 1Most of the mass of molecules are in the...

Homework Statement NH3 (ammonia) that is shown in the picture. These three hydrogen-atoms is formed as triangle. Center of the triangle has a distance d = 0.940 from each hydrogen atom. The nitrogen atom located in the vertex of a pyramid in which the three hydrogens defines "the base"...

Say, we have a solution of pure form of R-alanine. Say, the molecule has it's COOH group directed along positive y-axis and rotates the z-polarized light clockwise - the question is why the same molecule with it's COOH group in negative y direction won't do the opposite.

Homework Statement I have attached a solution to one of my homework questions that states "Draw hydrogen bonds that might be formed between a water molecule and the following compounds: a) H3PO4; b) PO43-; c) aniline; d) pyridine; e) ethylamine; f) ethyl ammonium ion; g) acetic acid." My...

When a person breaths air, how many molecules were used in some form by people today and those before us? The question becomes complex if you consider carbon dioxide is known to be drawn in by plants, trees and such. But could the question be simplified by asking how long does it take for a...

Homework Statement I will try to translate the best I can: In 1cm3 of air, how much of it is molecules and how much is the space between them. diameter of 1 molecule is 0,1nm and is has a sphere shape. so R=0,1nm space=1cm3 Homework Equations V=4/3*R3*∏ n=N/Na=V/V0 Na=6,022*1023mol-1...

I know that you can split, say H2O by using electrolysis. From there the hydrogen atoms would go to the negative electrode (cathode) and the oxygen atoms would go to the positive electrode (anode). But what if you wanted to separate the two even more, such as pulling the hydrogen atoms to one...

Suppose I have a graph with velocity of a gas v on the x-axis and number of molecules N on the y-axis, how would I find the number of molecules with v>v_0, where v_0 is a given velocity?

Homework Statement http://img580.imageshack.us/img580/7492/50177994.jpg The Attempt at a Solution I first attempt part (a) since both parts are similar: (a) I need to know "v" in order to use the following equation to find the de Broglie wavelength: \lambda = \frac{h}{p}...

When breaking down a molecule using electricity, what determines how much of the substance is broken down per second. Is it the voltage, current, or something else I'm not thinking of?

This question was a lecture discussion topic during my Biophysics course at university. I missed the lecture and the question is bothering me. "Eukaryotes (multi-cell organisms) evolved into very large sizes whereas prokaryotes (single-cell organisms) remained quite small (about 1...

Does anybody have ideas for experiments that I can perform to investigate the title? I am working on a science project at the moment. Thanks very much for any help given.

Homework Statement I can't answer to that question, and I don't know how to. I have to calculate the average separation between H2O molecules in pure water. Homework Equations The diameter of the molecule is 0.29 nm I think we can use the bohr equation to resolve it? r = (ε0*h2)...

Hi I was wondering if anyone knows about how molecules are distributed throughout various layers of the atmosphere. My assumption is that most molecules would be more abundant in the troposphere and decrease throughout until the mesosphere. does anyone know a little more about this or any...

Homework Statement A 32 u oxygen molecule moving in the +x direction at 1100 m/s collides with an oxygen atom of mass 16u moving at 1648 m/s at 38 degrees to the + x-axis. The particles stick together to form an ozone molecule. Find the velocity of the ozone. Homework Equations Not sure The...

Imagine light of frequency \Omega enters a liquid and propagates in the z direction. Its velocity is reduced to c/n. This leads to reduction of its wavelength to 1/n of the vacuum wavelength and the wave is described by the macroscopic electric field \mathbf E (\mathbf x,t) = \mathbf E_0...

Could lone subatomic particles be "stabilised" if placed in larger molecules? My main area is molecular biology and biochemistry, but I've had a growing interest in particle physics for a while. Could lone subatomic particles be "stabilised" if they were placed inside of a larger molecule...

Molecules in an ideal gas contained in a vessel are striking the vessels wall. I am trying to find the total kinetic energy of gas molecules striking a unit area of that well per unit time. The number of collisions per unit area per unit time is derived from the normalized Maxwellian...

I have been studying stereochemistry and it says that optically active molecules(chiral molecules) rotate plane of polarisation. I suppose that's because of the electrons in the molecule. I know that all molecules can rotate the plane of polarisation but when achiral moelcules are present in...

Homework Statement One model for the potential energy of a two-atom molecule, where the atoms are separated by a distance r, is U(r)=U0[(r0/r)13-(r0/r)9] where r0=0.85nm and U0=6.2eV. What is the distance between the atoms when the molecule is in stable equilibrium? Homework...

Homework Statement Approximately what fraction of molecules of a gas (assumed ideal) have velocities for which the angle φ lies between 29.5° and 30.5°, while θ lies between 44.5° and 45.5°? Homework Equations The Attempt at a Solution What does the question even mean...

Homework Statement The length of DNA helix occupied by one nucleotide pair is 3.4 A (angstrom). A human has 10^14 cells and each human cell has about 6.4 x 10^9 nucleotide pairs of DNA. What is the length of double helix that could be formed from this amount of DNA in a human individual...

Homework Statement The rms speed of the molecules in 1.1 g of hydrogen gas is 1800 m/s. 500 J of work are done to compress the gas while, in the same process, 2000 J of heat energy are transferred from the gas to the environment. Afterward, what is the rms speed of the molecules...

Homework Statement The two sides of the DNA double helix are connected by pairs of bases (adenine, thymine, cytosine, and guanine). Because of the geometric shape of these molecules, adenine bonds with thymine and cytosine bonds with guanine. The figure shows the thymine–adenine bond. Each...

In statistical physics we have for an ideal gas about the average kinetic energy for its molecules: Ekin=½kT Now in my book this is derived using the ideal gas law as an experimental fact, but that does not really help you get a deeper understanding, does it? I'm assuming that this can be...

http://bildr.no/view/1099870 The distribution of velocities of particles in this text is given by f(u) later in the text (the final part) they say that f(u) du gives fraction of gas molecules with speed between u and du+u. I thought that would only give a infinite small number since du is...

Hey, I'm wondering how you figure out the number of hydrogen bonds acting between molecules. I know each water molecule supposedly makes 4 hydrogen bonds with other water molecules through my reading, but I want to know how many for isopropyl alcohol, which has only one OH group. I know its less...

I think that buoyancy is caused by the increase of density with depth (the deeper you go, the more molecules there are per unit volume). Therefore an object in a fluid will be hit by more of the fluid molecules from below than from above (even if the difference is only a tiny fraction of 1%). Is...

Homework Statement Molecules of hydrogen, each has mass of 3.3 x 10-27 kg, move with speed 1.6 kms-1 hit a wall at angle π/3 rad to the normal. If there are 2.0 x 1020 molecules s-1 hit the area of 1.2 x 10-4 m2, find: a. the average normal force on the wall if all the molecules are absorbed...

I just don't get it... still... I don't get it at all... it makes no sense to me... Where can I learn how to read these ? does anyone have any insight as to a guide how to read these or can you explain ? I don't get how structural formula is read...

Hello there, I'm studying thermodynamics right now, and a question popped into my mind for which I haven't found a decent and detailed explanation so far. Say that we have a container filled with any kind of gas, and we can control the temperature of the wall of the container. If we increase...

When you heat the gases inside a hot air balloon it makes more sense (for myself at least) to say that it rises due to the velocity and kinetic energy of the molecules in their relation to the gases outside. Outside the balloon the molecules are obviously cooler, more dense, and moving slower...

I just read that the reason molecules rotate plane polarized light is because the light interacts with the electron cloud of the molecule. That makes sense but why aren't achiral molecules optically active? Achiral molecules have electron clouds too so why don't their electron clouds cause...

Homework Statement Which of the following will form a micelle? http://imgur.com/VFksg Homework Equations The Attempt at a Solution I know for sure that A, B and C are going to be micelles, since both are amphipathic molecules. They have a clear hydrophilic and hydrophobic part...

In Lorentz Ether Theory, object really get contracted, for example, a 6 foot man would become mere 1mm when traveling near the speed of light. They say SR and LET can't be distinguished because the performance of contracted atoms, molecules, etc. would be the same. Meaning if you were mere 1mm...

My question is about the energy exchange between gas particles and the walls of their container... If you consider a collection of gas molecules enclosed in a container, if the whole system is cooled (ie. like a balloon dipped in liquid nitrogen) as the gas particles collide with the inner...

Homework Statement Why may the specific rotation of a sample of (R)-(+)-limonene be less than the literature value of (R)-(+)-limonene. Assume that there are so (S) enantiomers present. Homework Equations The Attempt at a Solution There are no (S) enantiomers, but there are some...

Homework Statement At 0.0° C and 1.00 atm, 0.95 mol of a gas occupies a volume of 0.0213 m3. (b) Estimate the average distance between the gas molecules.

Homework Statement What fraction of the air molecules in a house must be pushed outside while the furnace raises the inside temperature from 17.0° C to 28.0° C? The pressure does not change since the house is not 100% airtight. Homework Equations v2/v1=17+273/28+273 =.963 Why is my...

For example: amino acids that are floating around, some with charge at physiological pH. My question is what exactly do the charged amino acids form a salt with? other amino acids? sugars? fatty acids? whatever happens to have an opposite charge and is close? A rephrasing: I am thinking...

If a tire is punctured (or if any container full of air is holed) the air starts to leak out. Consider a small area A of the wall of the container. Show that the number of molecules striking this surface in a time interval Δt is pAΔt/2m<Vx> p is the pressure m is the average mass of the...

Homework Statement To what pressure must a piece of equipment be evacuated in order that there be only 10^8 molecules per ml at 25 degrees celcius Homework Equations Ideal gas equation = PV = nRT Charles's Law = (V2/T2 = V1/T1) Avagadro's number (6.02 * 10^23) I know that at STP...

We know that air molecules are subjected to random motion in different directions. A sound wave is a push toward these molecules to make a wave front to make them expand or contract in groups so that we can hear a voice message in our ears. The question is that what happens when different...

Homework Statement A gas cylinder contains of 0.8 × 10^-3 m^3 volume oxygen.the temperature of the oxygen is 320k,and the pressure of the gas is 1.5 × 10^6 Pa.how to calculate: number of moles and molecules of Oxygen? mass of Oxygen if its molar mass is 32.0 × 10^-3 kg ? The mass of a single...

Homework Statement Hey guys. Hope you can help me out on this one. so here's the question: At an altitude of 50km the average atmospheric temperature is 0^oC. What is the average number of air molecules per cubic centimeter at this altitude. Homework Equations M = 28.97 g mol^-1...

Hi I am just wondering about this. How many molecules does it take before you can use the word Droplet in the atmosphere? As an example, one H20 molecule floating around (interacting occasionally with others, but generally just floating around) would be Vapour. If two H20 molecules...

Ok, this is a separate topic about Microwaves. I have come across claim that microwaved food is safe for health as long as the food is microwaved on a low power. This is because microwaves oven that are used on high power can strip ionise a water molecule and rearraange atoms in food...

The VSEPR theory states that whenever a molecule forms, it orients itself in space such that the repulsion is min and stability is maximum..now when propane forms their are 2 structures known one is propane(open chain) other is cyclopropane.. If VSEPR theory is not wrong then its cyclopropane...

Homework Statement the sulphur atoms in the self-assembled monolayers are ~ 4.99Å apart, and that they form a hexagonal close-pack structure, estimate the number of functional molecules/cm2 of the substrate Homework Equations 1 angstrom = 1.0 × 10^{-10} metres Area of hexagon =...

I know this is probably a stupid question, but do I just find the volume of the sphere using the 1 micrometer and divide that quantity by the average distance cubed?