Molecules Definition and 561 Threads

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...

Okay, so I was reading about how an air conditioner works. I was scrolling through the paragraphs until the sentence 'the closer the molecules are together, the higher its energy and its temperature'. Now temperature is the average kinetic energy of the molecules. Why is it higher when the...

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?

Hello, why much substances have one atom when aren't gas and 2 same atom united when are gas (for example N and N2, O and O2) ? Thanks!

What is the momentum of an oxygen molecule traveling at this speed? the speed was 484 m/s the molar mass of oxygen is M=.032 kg/mole Na= 6.022 x10^23 I do p=mv v=484 m=M/Na The answer should be 2.57x10^-13 but i keep getting 2.57 x10^-23

How can the bond angle in a molecules are measured ? The methods used to measure the angles and length b/w bonds.

Homework Statement Many diatomic (two-atom) molecules are bound together by covalent bonds that are much stronger than the van der Waals interaction. Experiment shows that for many such molecules, the interaction can be described by a force of the form F_{r} = A[ e^{- 2b( r - R_0 )} - e^{ -...

Hey all ! I've got a few questions regarding the Hartree Fock method which I'm not so sure about... Will HF result in a good estimate of the interaction energy between two Methane molecules ? and what about the structure and symmetry of Methane molecule ? (I know that as far as structure is...

Hi! I'm wondering what the effects of a variable mass of elementary particles on the rotational and vibrational energy-transitions would be like? Would they increase, decrease or stay the same? Thank you for your help! Regards

Just curious what the best way to pull off an image from Molden is? To me it seems that Print Screen is a bit of a silly way to do it; any suggestions?

the buckyball has between 20-60 atoms. This is a fairly large size. even if we "bounce" a photon or two off it, the molecule should not be effected. Thus can we use some method to find out which slit the molecule went through, without disturbing the interference pattern? or is it that, even...

have fullerene molecules (buckyball) been (quantum) entangled yet?

I just finished up my first class of chemistry, and have a question on something that I just can't figure out. The delta H of formation for diatomic molecules is 0. I just don't understand why this is. If there is a reaction, and O2 is one of the products, why is there no heat released when...

Could someone please explain the general idea of the Hartree Fock method to optimize the geometry (and energy) of a molecule. I understand that in the atomic case, one uses atomic orbitals and optimizes these, but in a molecule (especially polyatomic, say water or benzene) I am a bit confused...

So, I was brushing my teeth and started thinking about pi and how it is irrational. One thing led to another and I remembered Atom, by Asimov (which I haven't yet finished). Now, assuming pi is irrational, if we have a wheel with a radius of 1/2 (units don't really matter), and unroll it so that...

Homework Statement An insulated cylindrical reservoir of height H is suspended vertically in the field of gravitation. Find the average potential energy of the molecules in the reservoir. Homework Equations F = \frac{Gm_{1}m_{2}}{r^{2}} The Attempt at a Solution To be honnest I have no clue...

Homework Statement Why is <vx> = 0 this is a gas molecule Homework Equations The Attempt at a Solution I don't understand how the velocity could ever be zero?

hi, i need to explain how molecules of ethene combine together to form a poly(ethene) molecule? would it be because the double bond is broken and 2 bonds them placed on the outside of the Carbons (C)? if this is not correct could someone please let me know where I am going wrong! thanks!

Hi there, Ok from my lectures: Temperature is due to the Kinetic energy of molecules. Kinetic energy can be due to vibrational, rotational, translational and/or electronic motion. Now when you move an object from one place to another, aren't the molecules undergoing a nett translation...

Hi there! I'm studying that if r is the quantum number associated with the total angular momentum of a diatomic homonuclear molecule, then only odd or even values are allowed for r. Now, the selection rules for r requires a change of one unity, but if my molecule has only odd values for r...

Homework Statement What percentage of molecules in water at 300K will have a speed greater than 1 km/s (evaluate numerically)? Homework Equations The Attempt at a Solution Based on what we did in class, I take it I'm supposed to integrate the distribution from 1000 to infinity...

i was discussing with ma friend about the possibilities of inducing more vibration to the molecules in a solid matter... but we could not find a process to do that even though its not practical wanted to know some thing that is theoretical... hope some one is going to give new ideas..

Homework Statement In this problem, the surface tension S represents the work done to the water when increasing the water's surface area. The vaporization temperature Qvap represents the energy needed per volume unit to vaporize water at 100 degrees Celsius. We imagine that water molecules...

account for the fact that air molecules have a smaller mass? I have down in my notes something about if a larger particle was used then the average impulses would tend to 0, could someone please explain this? thanks a lot !

Homework Statement The molecular bond between the carbon and oxygen atoms in the diatomic carbon monoxide molecule can be treated as a spring with elastic constant k. The carbon atom has a mass of 12 amu and the oxygen atom has a mass of 16 amu, and the average separation of the two nuclei...

If buckyballs display uncertainty in the double slit experiment, shouldn't iodine gas molecules as well? An I2 molecule is certainly less massive than a buckyball. Yet why can we see I2 gas as a purple haze? I can see it, almost in the same way I can see my pencil, which has a very small...

1. Estimate the number of oxygen molecules in LTD under normal pressure and temperature. 2. I'm guessing you use PV=nRT to get the number of moles of gas in the room and work out the % of oxygen in the air, but I got a number which to me looks too small. 3. Volume of LTD is approx...

Homework Statement A 4.0 m^3 container of oxygen gas has a gauge pressure of 8x10^5 Pa at 25 degrees c. a) how many moles of oxy are present in the containe?r ANS: 1292 moles b)how many oxy molecules are present? ANS: 7.78E26 oxy (yes, i have the answers but i don't know how to get to them...

Unstable molecules - is the instability "relative" to environment? There are many highly unstable chemical configurations. Most chemicals, after all, would prefer to move from high-energy states to low-energy states. This is usually possible due to the presence of a reaction pathway that makes...

Homework Statement At a height of 300km above the Earth's surface, an astronaut finds that the atmospheric pressure is about 10-8 mmHg and the temperature 500 K. How many molecules are there per milliliter at this altitude? Homework Equations The Attempt at a Solution I first...

Say I have a molecule with two metal centers and some bridging ligands binding the two metal centers, how do I know whether the molecule is ferromagnetic or antiferromagnetic (or neither)? What exactly dictate whether this molecule would be ferromagnetic or antiferromagnetic?

Homework Statement Hullo I'm working through a textbook, and I've come across this expression which I don't follow at all.. the section is headed 'Velocity distribution of moledcules in a gas'. I follow it up until this integral, but I've not got a clue how they do it. I've had a couple...

Why does heat cause certain things to break into their basic elements?

Why do some atoms bind with other atoms of their own elements, such as O2 and N2, and why do others not? What property of these atoms enable them to do this?

This might be a stupid question, but it has me kind of confused. In diffusion, molecules will flow from high concentration to low concentration, and the explanation typically given is that in the laws of thermodynamics there is a net increase in entropy over time. But I am trying to think of...

This question has been bugging me for a while, I thought that it was due to the atoms electrons moving faster, making the atom basically also move around more.

Water molecules are polarized, so why don't the molecules in a glass of water simply line up with opposite + and - ends and come to a halt?

How do you figure out what the shape of molecules are. For example, Water. 1 part oxygen and 2 parts hydrogen with 104.45 degrees between the two hydrogen. That's what I want to figure out. I imagine it has something to do with the electrostatic force.

how can i know what the names of the molecules in this list:C3H8. SO3, F2, KBr (the numbers need to be little) thanks.

How do you determine the shape of molecules. water, as an example, the 2 hydrogen atoms are at a 104.45 Degree angle from each other. But how is that calculated? I'm assuming it has something to do with the ratios of the electrostatic forces between the 2 hydrogen and the oxygen.

hi, Could anyone help me the following question? I am reading light transmission through a slab of air (at the ambient atmosphere). My question is: How much light is transmitted without hitting any air molecules? In details: An incident light beam propagates through a slab, of some...

Uranium nitride rips the hydrogen atoms off a carbon atom -- but unfortunately, the UN is destroyed in the process. http://news.discovery.com/tech/uranium-nuclear-power.html I don't why is considered new, since UN has been around for more than 25 years. It was considered for compact...

Homework Statement When forming a micelle, molecules such as fatty acids, detergents and lysophospholids form micelles on the basis that the cross sectional area of the head group (I'm guessing the polar part that interacts with water) must be greater than the acyl side chain...but what...