CHEMISTRY COMMUNITY

Kimberly Koo 2I

This would depend on the situation given, but generally, you would want to manipulate the equations so that you end up with the standard potential of the cell being positive (the reaction is spontaneous). Use the equation E(cell)=E(electrode on right of cell diagram)-E(electrode on left of cell diag...

Kimberly Koo 2I

Enthalpy can be found using the equation H=U+PV, or deltaH=deltaU+deltan(gas)RT

Kimberly Koo 2I

Delta S total is the entropy of both the system and its surroundings, while delta S surroundings is just the entropy of the surroundings and not the system.

Kimberly Koo 2I

The order of a reaction depends on the number of reactants in the reaction. For example, if a reaction has O2 with a coefficient of 2 that are reactants, then the order of the reaction is second order. If a reaction has CO2 with a coefficient of 1 and H2O with a coefficient of 1 in the reactants, th...

Kimberly Koo 2I

An electrolytic cell converts electrical energy into chemical energy, while a galvanic cell converts chemical energy into electrical energy.

Kimberly Koo 2I

In the Arrhenius equation k=Ae^-Ea/RT, A is the "pre-exponential factor" or frequency factor, the frequency of collisions and their orientation, Ea is the activation energy, T is temperature, and R is the universal gas constant.

Kimberly Koo 2I

The rate law equations can be used to predict a rate concentration, the concentration of reactants, or the rate of a reaction.

Kimberly Koo 2I

First order means that the concentration of a single reactant is raised to the first power. For a second order reaction, the concentration of 2 reactants is raised to the first power or the concentration of a single reactant is raised to the second power. The order of a reaction is determined by the...

Kimberly Koo 2I

Because zero order reactions are equal to the rate constant, k. In different order reactions, the concentrations are put to the power of the reaction's order, and in the case of zero order reactions, the concentration is put to the power of 0, and anything to the power of 0 is equal to one, so the c...

Kimberly Koo 2I

Collision theory states that in order for a reaction to occur, the molecules participating must collide with each other. The rate of the reaction depends on the frequency of the collisions. Transition state theory regards chemical reactions as a continuous change in the relative positions of molecul...

Kimberly Koo 2I

Yes, I'm also pretty sure a galvanic cell can never have a negative E cell

Kimberly Koo 2I

First order reactions have a graph that looks linear and the slope of the graph is -k

Kimberly Koo 2I

The oxidation agent causes another substance to be oxidized, which is why the oxidizing agent is different from what's being oxidized

Kimberly Koo 2I

Electromotive force is the electrical potential generated from a system (like a galvanic cell)

Kimberly Koo 2I

Diamond is kinetically stable with respect to graphite because the path for diamond becoming graphite has a larger activation energy barrier that makes the diamond less ready to transition to graphite, so diamond is kinetically stable.

Kimberly Koo 2I

Amount of electrical charge carried by one mole

Kimberly Koo 2I

Both of the Ce molecules are in the aqueous phase, so they both need an inert electrode.

Kimberly Koo 2I

The anode is always placed on the left side and the cathode is always on the right side.

Kimberly Koo 2I

If the value of E is negative, then it means that the reaction in the forward direction is not spontaneous, while the reverse reaction is spontaneous.

Kimberly Koo 2I

This is because delta H is a state function while E is not. So delta H doesn't depend on anything but the initial and final state, which is why we can use Hess's law.

Kimberly Koo 2I

If Gibbs free energy is negative, then the process is spontaneous in the forward direction. If the Gibbs free energy is positive, then the process is nonspontaneous in the forward direction and spontaneous in the reverse direction.

Kimberly Koo 2I

Delta H remains constant in the Van't Hoff Equation, since its under the assumption that temperature changes little enough that delta H can be considered constant throughout the reaction.

Kimberly Koo 2I

You would use the equation to figure out how the value of K would change if the temp. of the reaction increased, and you are trying to find the K value given the 2 temperatures.

Kimberly Koo 2I

That equation is used when the system is at equilibrium.

Kimberly Koo 2I

No, we don't include spectator ions in the equilibrium constant

Kimberly Koo 2I

I found this in a helpful table in section 4C.3 of the textbook. It is part of a set of values that correspond to what the values of Cv,m and Cp,m would be depending on if the question asks about an atom, linear molecule, or nonlinear molecule.

Kimberly Koo 2I

The second law of thermodynamics states that the entropy of an isolated system increases from any spontaneous change. An example of this would be how the spontaneous cooling of hot metal in a cold environment causes an increase in entropy since the heat spreads to the surroundings. The third law of ...

Kimberly Koo 2I

A irreversible process is where the system will not go back to its initial state, no matter what factors are changed.

Kimberly Koo 2I

Intensive properties don't depend on the quantity of matter that's being measured, while extensive properties do depend on the quantity being measured. An intensive property would be density while an extensive property would be volume.

Kimberly Koo 2I

The system is what we're interested in, and the surroundings are everything else around the system

Kimberly Koo 2I

R is the universal gas constant, which is equal to 8.314 J/mol.K

Kimberly Koo 2I

Since degeneracy is the number of ways to achieve a particular energy state and entropy is the likelihood that the system will be in a particular state, degeneracy (W) being at a maximum probably means that the number of ways to achieve a particular energy state is the highest.

Kimberly Koo 2I

Yes, since the equation is s=Kb(lnW), it relates degeneracy and entropy

Kimberly Koo 2I

In an isolated system, no exchange of any kind can happen between the system and the surroundings, while in a closed system, energy can be exchanged between the system and the surroundings. The examples given in class were the bomb calorimeter being a isolated system while a sealed beaker is a close...

Kimberly Koo 2I

Enthalpy is a state property because its value isn't dependent on the path taken to obtain that state

Kimberly Koo 2I

Yes, because in this case water isn't in the pure liquid form.

Kimberly Koo 2I

The standard enthalpy of O2 is 0 since the reaction goes from O2-->O2, the O2 is already in its most stable form

Kimberly Koo 2I

0.08206 L.atm.mol.K

Kimberly Koo 2I

A state property is a property where its value does not depend on the path taken to get to its current state. In class Lavelle explained how the properties can be added or subtracted, since the value only depends on the first state and the last state.

Kimberly Koo 2I

Since PV=nRT can be converted into the equation P=(n/V)RT and R is a constant, we can convert from partial pressures to concentration to find K and vice versa

Kimberly Koo 2I

Le Chatelier's principle explains how chemical reactions adapt to a change in physical parameters like temperature, pressure, or volume.

Kimberly Koo 2I

The change in solvent concentration is insignificant, which is why pure liquids are eliminated from the equilibrium expression.

Kimberly Koo 2I

If the reaction is endothermic, then heating higher than 25 C favors the forward reaction and creates more product. If the reaction is exothermic, then cooling to less than 25 C favors product formation, while heating will favor reactant formation.

Kimberly Koo 2I

R is the universal gas constant, which is 0.082 L.atm/mol.K

Kimberly Koo 2I

Usually the products have a positive change since there are more products being created and the reactants have a negative change since reactants are being used to make products.

Kimberly Koo 2I

To solve this, you use the ICEbox method. ICE stands for initial concentration, change in concentration, and equilibrium concentration. This method tries to create a quadratic equation where you can solve for the variable x. You would use the balanced chemical equation to represent the unknown chang...

Kimberly Koo 2I

Removing some of the NH3 makes the reaction form more products to reach equilibrium, so more NH3 would be produced

Kimberly Koo 2I

Comparing the reaction quotient to K tells us which direction of the reaction is favored. So if Q>K then the reverse reaction is favored since this means that there are more products than reactants in the nonequilibrium concentration Q. If Q<K, then the forward reaction is favored since this means t...

Kimberly Koo 2I

Solids and liquids are not included in the equilibrium constant because their concentrations stay constant throughout the entire reaction

Kimberly Koo 2I

-ido and -o are a part of different naming guidelines, but Lavelle said it was fine to use either

Kimberly Koo 2I

Lewis acids are able to accept electrons, so they are normally electron deficient molecules

Kimberly Koo 2I

When something has stronger intermolecular forces, the boiling point is generally higher. For example, if a molecule has H-bonds, it'll have a higher boiling point than a molecule with only London Dispersion Forces, as LDF are weaker than H-bonds.

Kimberly Koo 2I

Cisplatin is able to attach to DNA and stop cell division, which is why it is used in treating cancer

Kimberly Koo 2I

Both pKa and Ka are used for determining how acidic a molecule is

Kimberly Koo 2I

Strong acids when reacting with water have a higher concentration of H3O+, and when acids are broken in water, protons (H molecules) are transferred to a water molecule to produce H3O+.

Kimberly Koo 2I

An oxoacid is an acid that contains oxygen

Kimberly Koo 2I

I googled this and found that bases feel soapy when we touch them because our skin has fatty acids, and the bases react with these fatty acids to actually create some soap on our skin, leading to the soapy feeling.

Kimberly Koo 2I

Transition metals are in the d-block, groups 3-12. Examples of transition metals are copper and chromium

Kimberly Koo 2I

The transition metals in the d-block are more electronegative than the metals in other groups.

Kimberly Koo 2I

You count the numbers of bonds and lone pairs (regions of electron density) around the atom and then match this number to the matching hybridization. Sp has 2 regions of electron density, sp2 has 3 regions of electron density, sp4 has 4 regions of electron density, etc.

Kimberly Koo 2I

Usually if a central atom is surrounded by more than one outer atom, then it has to hybridize.

Kimberly Koo 2I

A coordinate covalent bond is a bond where both electrons come from only one of the atoms in the bond. An example of this would be BF4-

Kimberly Koo 2I

In terms of making actual calculations, a bond is considered polar if the difference in electronegativity of the atoms in a bond is larger than 0.4. If the difference is less than 0.4 than the bond is nonpolar.

Kimberly Koo 2I

Most acids are weak, but an acid that fully dissolves into ions is a strong acid while an acid that doesn't fully dissolve into ions is a weak acid.

Kimberly Koo 2I

Hydrogen bonding occurs when a H is bonded to a small atom that's very electronegative, like N, O, or F. So NH3 can form hydrogen bonds

Kimberly Koo 2I

Ions are different from regular atoms because they are charged, either from taking away an electron or adding one. Their electron configuration differs because it will have a greater or smaller number of electrons in the configuration, depending on if the atom becomes a cation or anion

Kimberly Koo 2I

Lone pairs occupy more space around the central atom than bonding pairs and lone pairs are also more impacted by electrostatic repulsion between like charges

Kimberly Koo 2I

VSEPR assumes that each molecule in an atom will have a shape that minimizes the repulsion between valence electrons. This model helps us determine the shape of molecules and their bond angles.

Kimberly Koo 2I

Hydrogen bonding is the strongest, followed by ion-dipole interactions, then dipole-dipole interactions, and then London forces

Kimberly Koo 2I

When molecules are larger and have a higher molar mass, then they have more electrons, which means that they have more attractive interactions.

Kimberly Koo 2I

The calculation for the dipole moment actually tells you the measurement for the separation of two opposite charges of molecules.

Kimberly Koo 2I

The dipole dipole interaction happens between a fully charged ion and a partially charged dipole. The induced dipole interaction happens between a fully charged ion and a temporarily charged dipole.

Kimberly Koo 2I

Ion-dipole forces result from attraction between a neutral molecule with a dipole and an ion. These forces become stronger as the charge on the ion increases.

Kimberly Koo 2I

Ionization energy is the amount of energy needed to remove an electron from a neutral atom. Electron affinity is the change in energy from a neutron attracting an electron, that when present, causes a negative charge on the ion. Electronegativity is the ability of an atom within a molecule to attrac...

Kimberly Koo 2I

Schrodinger's equation uses a wave function to describe the electrons in an atom since electrons have wavelike properties.

Kimberly Koo 2I

That should be correct since the Bohr frequency condition says that hv=E upper-E lower

Kimberly Koo 2I

Bohr's frequency condition is that hv=energy of the upper state-energy of the lower state. So Planck's constant (6.626x10^-34) multiplied by velocity is equal to the difference in energy between the upper energy state and the lower energy state

Kimberly Koo 2I

Hydrogen bonding is a type of dipole-dipole interaction. The hydrogen bonds are more commonly found in water molecules and are usually stronger.

Kimberly Koo 2I

The question asks, how many orbitals can have the following quantum numbers in an atom? a) n=3, l=1, b) n=5, l=3, ml=-1, c) n=2, l=1, ml=0, d) n=7. I'm not sure how to find these answers, could someone please explain? Thank you!

Kimberly Koo 2I

I don't get how to solve this problem. It states that, "What is the minimum uncertainty in the speed of an electron confined within a lead atom of diameter 350. pm? Model the atom as a one dimensional box with a length equal to the diameter of the actual atom". Thank you

Kimberly Koo 2I

Oxidation numbers are found by assigning the electrons in the covalent bond to the more electronegative atom in the bond. The formal charge is different because the number isn't determined by which atom is more electronegative.

Kimberly Koo 2I

A resonance hybrid is a molecule that has resonance and its structure is represented by a combination/average of multiple structural formulas. The formulas are separated from each other by arrows.

Kimberly Koo 2I

Cations are smaller than their parent atoms because they are formed by a loss of electrons from the parent atom, while their nuclear charge stays the same. This makes the electrons stay closer to the nucleus, and therefore make the cation smaller than the parent atom.

Kimberly Koo 2I

Molecules that have resonance are known to be more stable since the double bonds can be placed in more different positions. So a molecule that can form 2 different structures is less stable than a molecule that can form 4 different structures, but is more stable than a molecule that doesn't have res...

Kimberly Koo 2I

h bar is also good for calculations that have precise measurements dealing with subatomic particles

Kimberly Koo 2I

Option a, 2d, does not exist because d orbitals don't exist until the third energy level. 4d can exist because this indicates 5th row transition metals in the periodic table. 4g does not exist because g orbitals only exist in energy levels 5 or greater. 6f can exist because it is in the lanthanoids/...

Kimberly Koo 2I

The Lyman series is the ultraviolet region of light while the Balmer series is the visible region of light. The Lyman series drops to n=1 while the Balmer series drops to n=2

Kimberly Koo 2I

Hi, I was reading the textbook and it says that complementarity if the impossibility of knowing the precise position of a particle even if the linear momentum is known since momentum and location can't be known at the same time. I'm still a bit confused on why momentum and location can't be known at...

Kimberly Koo 2I

Hi, could someone explain how to do question 1A.15 to me? The question says, in the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral lin...

Kimberly Koo 2I

No the speed of does not remain constant, a case where it changes is when it goes through multiple different mediums.

Kimberly Koo 2I

Why does the frequency of light remain constant when the light travels through different mediums even if the wavelength and speed change?

Kimberly Koo 2I

In my lecture notes, I had written a lot about particles having "wavelike properties" and "measurable wavelike properties" and how a particle must have wavelike properties to work in DeBroglie's wave equation. Can someone expain exactly what these "wavelike properties" ...

Kimberly Koo 2I

Problem 1A.9 gives a situation where throughout the day, a student does 4 different activities involving radiation from different parts of the electromagnetic spectrum (reading, getting a dental x-ray, microwaving popcorn, and getting a tan). Then it asks you to complete a table with frequency, wave...

Kimberly Koo 2I

Since each photon interacts with an electron (1 photon interacts with 1 electron), the frequency is considered high enough when the energy per photon is greater than or equal to the energy needed to remove an electron. The energy needed to remove an electron usually depends on the situation in the p...

Kimberly Koo 2I

Hi, on tests will we lose points in our answer if we don't use the "multiple powers of 10" in our calculations and answers? (like how an answer could be written as 0.002 or 2 x 10^-3). Thank you!

Kimberly Koo 2I

Positive powers will indicate that the number is larger/higher while negative powers usually indicate that the number is smaller/lower. For example something that is 10^4 would equal 10,000 while something that is 10^-4 would equal 0.0001.

Kimberly Koo 2I

I think you can never get an exact actual yield just using a theoretical yield since an actual yield is what comes from the lab and generally will vary depending on who does the experiment and the outside conditions.

Kimberly Koo 2I

t probably means ton. The conversion would be 1 ton=1,000,000 grams. Hope this is helpful!

Kimberly Koo 2I

Question E15 says that the molar mass of metal hydroxide M(OH)2 is 74 g.mol^-1 and then asks for the molar mass of the chloride of this metal. I did not see any chloride in the molecular formula so then I checked the answer key and they solved for the molar mass of another different substance, calci...

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