CHEMISTRY COMMUNITY

Julia Campbell 2F

Just wanna thank my #1 fan, my snake roommate Nicole. She has supported me this entire year through thicc and thin.

Julia Campbell 2F

For the final I'm pretty sure we won't have to draw them ourselves, but we may be given a graph of one and have to figure out what order it is.

Julia Campbell 2F

SI units and any conversions on the constants and equations sheet are fair game.

Julia Campbell 2F

No you'll get the test back in discussion as usual.

Julia Campbell 2F

Rate=−d[A]dt=k[A]0=k=constant

Julia Campbell 2F

Molecularity is just the number of molecules that come together to form a reaction so I think there could be different molecularities for the elementary reactions and the overall reaction but probably not often. The order of a reaction depends on the pathway of the overall reaction so I would think ...

Julia Campbell 2F

I don't think there'll be anything past #45 because we just started elementary steps and so on on Monday.

Julia Campbell 2F

Kinetics deals with the rate of a reaction and thermodynamics deals with whether the reaction is favorable or not. A kinetically controlled reaction is one that does not occur because of a large activation energy barrier even though the products have a lower standard Gibbs free energy (i.e., the rea...

Julia Campbell 2F

It is also because, when graphed, the slope is negative (going to the right and down). So, for the slope to equal k, k must be negative as well.

Julia Campbell 2F

I think because the product also has a coefficient of two so it's a 1:1 ratio. Or maybe the concentrations given already factored that in.

Julia Campbell 2F

Just remember that the anode half reaction is oxidized and the cathode half reaction is reduced. So, in part d, for the E of the cell to be positive (which it needs to be), the bigger positive E of either half reaction must go first in the equation (Ecell=Ecathode-Eanode). The bigger positive voltag...

Julia Campbell 2F

The anode half cell is described first, then the cathode half cell (so that as you read it, your eyes move in the direction of the electrons). Within a given half-cell, the reactants are specified first and the products last. A single vertical line is drawn between two chemical species that are in d...

Julia Campbell 2F

The cathode half reaction is O2 + 4H+ + 4e --> 2H2O. The anode half reaction is O2 + 2H2O + 4e --> 4OH-. So, to write the cell diagram, you have Pt on either side (think of the sides as almost symmetrical) and O2 on either side (inside the Pt), but the ions are H+ and OH- so since the H+ is in the c...

Julia Campbell 2F

An open system is also like a cup of coffee for example. You can exchange matter into or out of the system, like adding sugar to the coffee.

Julia Campbell 2F

They are conceptually a little different but yes, I think the variables you listed would all be zero for both.

Julia Campbell 2F

The second law of thermodynamics states the total entropy of the universe, an isolated system, can never decrease over time since energy can never be destroyed. The third law of thermodynamics states that the entropy of a perfect crystal at absolute zero, assuming it is at equilibrium, is exactly eq...

Julia Campbell 2F

The kinetic, vibrational, rotational, and electronic energies of the particles determine the heat capacity of a system, so I would think (out of the three things you listed) that bond energies would matter the most in determining heat capacity.

Julia Campbell 2F

Common salts to use include potassium chloride, sodium chloride, or potassium nitrate. The electrolytes chosen should not react with any of the chemicals used in the cell, and the anion and cation should have similar conductivity.

Julia Campbell 2F

The salt bridges maintain the neutrality in the two solutions. As electrons flow from the anode to cathode in the wire, the negatively charged ions migrate to the anode half cell using the salt bridges so that the solution in that half does not become positively charged, and vice versa for the catho...

Julia Campbell 2F

A more complex molecule has more possible positions it may attain (since there are more atoms involved) which is one way we measure entropy.

Julia Campbell 2F

Standard entropy specifically means that every reactant and product is in its purest state (i.e.: H2 gas) and that 1 mole of product is produced.

Julia Campbell 2F

Yes exactly, when G is negative (so when the slope on the graph was negative) the reaction is spontaneous. When G (or the slope) is positive, it is not spontaneous.

Julia Campbell 2F

Yeah pretty much, standard enthalpy of formation is assuming that everything is in its most stable form and there is one mole of product.

Julia Campbell 2F

I don't think so. I'd stick to the outline he gave.

Julia Campbell 2F

So when calculating standard enthalpy using bond enthalpies, the mean bond enthalpies provided will be for those bonds in the gaseous phase. In order to calculate the standard enthalpy of a reaction with something in a liquid or solid form, just use the bond enthalpies as you normally would then aft...

Julia Campbell 2F

When something is in its most stable form, the standard enthalpy of formation is zero because in a reaction it wouldn't change in any way to stabilize since it is already how it wants to be

Julia Campbell 2F

Use whatever information is given to you, but yes Hess's Law is more accurate.

Julia Campbell 2F

The solutions manual probably just meant per mole of reaction. It's the same as just saying kj because it is implied that it it kj per mole of reaction.

Julia Campbell 2F

The bond order of CN is 2.5 because 0.5(7-2)=2.5. You subtract the nonbonding electrons from bonding electrons first, then divide by 2.

Julia Campbell 2F

Delocalized bonds is when the electrons in the bond can move around so the bond can change, like in resonance structures.

Julia Campbell 2F

A reagent is used in a reaction and a reactant undergoes a change in a reaction.

CHEMISTRY COMMUNITY

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Re: graphs

Re: units

Re: Kinetics Test Scores [ENDORSED]

Re: Deriving Zero Order Half Life Equation

Re: Molecularity vs Order

Re: Question about Test #3

Re: Kinetics vs Thermodynamics

Re: Calculating slope

Re: Homework Problem 15.3

Re: 14.21

Re: Cell Diagrams [ENDORSED]

Re: 14.15 part b

Re: Open System

Re: Free Expansion

Re: 2nd and 3rd law of Thermodynamics

Re: Heat Capacities of Dense Elements

Re: Salt Bridges

Re: Salt Bridges?

Re: Entropy Change factors

Re: Entropy vs. Standard Entropy

Re: Graph of G

Re: Reaction Enthalpy

Re: Average Kinetic Energy

Re: Bond enthalpies

Re: 8.51

Re: Bong Enthalpy accuracy [ENDORSED]

Re: 8.45

Re: Bond Order

Re: delocalized pi bond

Re: Reactant vs. Reagent [ENDORSED]