INTERMOLECULAR FORCES
What is an intramolecular and intermolecular force?
Intramolecular- interaction within a single molecule (covalent bond)
Intermolecular- interaction between two different molecules
What are the different properties of solids?
Very strong interactions between particles, have definite shape and volume, regular, crystalline structure, fixed arrangement of particles, vibrational degree of freedom
What are the states of matter dictated by?
The kinetic energy of particles and a substance's heats of fusion/vaporization, as well as pressure and temperature
What is the ideal gas constant? What are it's variables?
PV = nRT
P: Pressure , V: Volume , n: Number of moles , R: The Ideal Gas Law Constant , T: Temperature
What is kinetic molecular theory?
What are properties of dipole-dipole interacitons?
Occur between any two polar molecules, can be attractive or repulsive, molecules orient themselves to maximize attraction, the strength of the interactions is directly related to the magnitude of the dipole.
What are the different types of solids and their examples?
Ionic- NaCl , Metallic- Al , Molecular- H2O , Covalent Network- Diamond
A significantly larger spacing between the molecules must exist.
What is Dalton's Law of Partial Pressures?
Ptotal = PA + PB + PC + ...
What does a Maxwell-Boltzmann distribution show?
How particle speeds are distributed in a sample.
What does the strength of London dispersion forces rely on?
How easily the electrons can disperse. The larger the electron cloud, the more polarizable it is; thus, the greater strength of the interaction.
Why are ionic solids brittle?
What degree of freedom does solid water have?
Molecules are moving but not past each other- SO, there is a vibrational degree of freedom.
What is a mole fraction and its equation?
Mole fraction is the ratio of moles of one gas mixture to the total number of moles of gases: Xi = ni / ntotal
What should the X and Y-axis represent in a Maxwell-Boltzmann Distribution?
Y-axis: Shows how frequently that particle speed is found in the sample.
Melting point, vapor pressure, volatility, surface tension, viscosity, heat of vaporization
Describe the melting and boiling point of molecular solids and why.
Relatively low melting and boiling point due to the weak intermolecular forces holding molecules together.
What is the molecule movement like in gaseous water? What degrees of freedom?
Molecules in the gas phase move randomly in straight lines between collisions- all degrees of freedom: vibrational, translational, rotational.
What is the effect of V on P?
As volume decreases, pressure increases- and the greater concentration of particles results in a greater frequency of collisions.
Pressure and volume are inversely proportional
How are gasses with different masses affected at different speeds and how does it affect the Maxwell-Boltzmann distribution graph?
More massive gasses move more slowly, so the curve is mostly to the left.
Less massive gases move faster on the average, so the curve stretches more to the right and flattens.
Which substance's molecules experience stronger IMFs, propane or ethanol?
propane, C3H8, 44 g/mol ethanol, C2H6O, 46 g/mol
Ethanol molecules experience stronger IMFs. The two molecules have approximately the same mass. Propane molecules experience only LDFs, while ethanol molecules experience LDFs, dipole-dipole forces, and hydrogen bonds.
Which of the following could be the identity of a white crystalline solid that exhibits the following properties: it melts at 360°, it does not conduct electricity as a solid, it conducts electricity in an aqueous solution.
A) C12H22O11(s) B) KOH(s) C) C(s)- diamond D) Ag(s)
B) KOH(s)
What remains constant and what differs as different states of matter are reached?
Particles retain their chemical identity in all three states, but the volume, density, and interparticle distances are different.
Predict the effects on the other variables when-
A gas in a rigid container has a pressure of 6.0 atm. The container is opened until the pressure is reduced to 3.0 atm, and then closed again.
n= reduced by half , V= constant , T= constant
An experiment to compare the deflation rate of different gasses is set up. Helium and argon are chosen and are inflated in two identical balloons to the same pressure, volume, and temperature. The helium balloon deflates faster than the argon one. A student thinks that the helium balloon deflates more rapidly because helium atoms have a smaller volume and can more easily fit through the microscopic holes in the balloon. Do you agree or disagree with the claim? Explain with principles of kinetic molecular theory and properties of both gasses.
No because the mass of He is less than the mass of Ar, the He atoms move at a higher average speed which increases the chances of the He atoms effusing out of the balloon. Even though the sizes of the two atoms are different, the difference is negligible compared to the holes in the balloon through which they effuse.