CHEMISTRY COMMUNITY

Yeyang Zu 2J

It would be a negative slope linear line. Y axis is reaction concentration, whose interaction is A0. The x axis is time, as time goes, the reactants consumes and its concentration decreases

Yeyang Zu 2J

It can be negative, which means as the substances decreases , the reaction rates increases. Try to think of the relationships between products and forward reaction

Yeyang Zu 2J

Reactant is something that truest reacts ( chemical changes)
Regent is things that is used in the chemical reaction, which do not necessarily to be chemically changed

Yeyang Zu 2J

I think we do not have to do so. But it is necessary to make sure that the units are all correct

Yeyang Zu 2J

Since you can get the answer in both ways so that I don't see a real need to convert ln to log. If it makes calculation easier for you, then it is o.

Yeyang Zu 2J

The graph is a linear line with time against [A]. The slope is negative, which equals to -k. The interaction point with y-axis is [A]0, which is the initial concentration of the reactant.

Yeyang Zu 2J

You can tell the reaction rate equation by simply looking at its chemical equation.
Rate equation is determined by experiment.
Only it works if the chemical reaction is a mechanical step of the reaction.

Yeyang Zu 2J

I will say the rate of a chemical reaction is the change in concentration over the change in time and is a metric of the "speed" at which a chemical reactions occurs.
And Unique rate is the rate occurs per unit of each molecules

Yeyang Zu 2J

Since Rate= mol•L^-1•S^-1
AND [A]= mol•L-1

First order rate = K1*[A]

And calculate the unit of K1

Yeyang Zu 2J

If 2A+3B—>5C
Unique rate equals to -1/2 * d[A]/dt = -1/3 * d[B]/dt=+1/5 * d[C]/dt

Yeyang Zu 2J

What’s unique rate in a chemical reaction?

Yeyang Zu 2J

why the cell uses two silver electrode then Ecell is zero
isn't Ecell depending on the concentration of solutions ?? ( which means the K=1)

Yeyang Zu 2J

Why the solution manuals writes Ecell*=0 for b) part as the concentration of H+ are not equal for reactants and products.

Yeyang Zu 2J

The textbook writes that (RT/F) ln 10 = (0.026 93 V) * 2.303 = 0.0592 V at 25 C, Ecell =Ecell'- (ET/F)ln10*og{H+} =Ecell'+ .0592 V* pH It is on the page 591, which is section 14.11 why equation changes the sign from "plus" to "minus" if (RT/F) ln 10 = (0.026 93 V) * 2.303 = 0.059...

Yeyang Zu 2J

Usually, anode is on the left, and the cathode is on the right. There are a wire connects the two part together. Besides, it needs a salt bright to balance the charge difference.

Yeyang Zu 2J

First, you can think of that everything is constant in the universe
Then, since Stotal=q(total)/T
Qtotal=zero
Stotal=0

Yeyang Zu 2J

For example, when a cell has lower concentration of glucose of the cell than that outside of the cell, It needs to use Na+,K+pump to create electrochemical gradient. The pump does work and create concentration difference to produce potential energy to perform actions

Yeyang Zu 2J

These two equation are essentially the same. There are two different form of the same equation. The only difference is that log has 10 as its base and ln has e as its base. However, adding the constant make the two value the same. If you want to apply the same thing to other equation, I would sugges...

Yeyang Zu 2J

TURE, remember the equation S=k*lnW, and W=(number of different micro-states for each molecule) ^ (number of molecule)
if the number of molecules increases, S definitely increases

Yeyang Zu 2J

Yes, you can only use the equation s=Qrev/T when it is a reversible expansion.

Yeyang Zu 2J

That's how Pro.Lavelle emphasizes in the lecture.
Positive signs mean gaining ENG and Negative signs mean giving ENG.
Probably for more accurate calculation and emphasize the direction of ENG flows.

Yeyang Zu 2J

I think it is because vaporization always happens with lost of energy of the liquid.

Yeyang Zu 2J

you can figure it out it two ways (question:A balloon filled with gas is expanded to a larger volume and lower pressure while maintaining the same temperature. Answer yes or no if heat is being transferred in the process. ) 1:since it is a isothermal expansion, delta T=0, then delta U=0. there is no...

Yeyang Zu 2J

Since Dr.Lavelle did mention it specifically, i think we could just use these equations. What matters is whether you understand the question and how to solve it, but not the mathematical calculation demonstration on equation

Yeyang Zu 2J

First, reversible process is one that can be reversed by an infinitely small change in infite-small change for example, 2 systems are both under 2 atm pressure, they could push/pull each other with a tiny small change in volume, it works the same for both directions however, if the 2 system are one ...

Yeyang Zu 2J

Work done by a system: the energy of system released to do work, which means the system loses ENG
Work done on the system: the energy done by the surroundings, like compressing the air, which means the internal energy of the system increases

Yeyang Zu 2J

Why on the solution manuals
the answer use the sum of enthalpy of reactant to minus the sum of enthalpy of products???
or do i misunderstand the meaning of ∆Hc is it meaning the enthalpy of formation ???

Yeyang Zu 2J

the truth is totally opposite.
when work is done by the system, w is negative (expand
when work is done by the environment to the system, w is positive (compress

Yeyang Zu 2J

when the system lost heat to its surrounding, q is negative

Yeyang Zu 2J

REPLY TO THE UPPER
Expand isothermally means that temperature stays the same, which means there is no heat transfer.All energy transfer comes form doing work. It applies to the isothermal expanding equation w=-nRT ln ( V2/V1)

Yeyang Zu 2J

NO HAS A DOUNVLE BOND
BUT NO2 HAS A resonnance structure, which means the strenth of the bond is between double bond and single bond
Therefore, NO has higher bond enthalpy

Yeyang Zu 2J

Since the purpose of the device is measure the heat of the substance released by burining it. Therefore, there should be no heat transfer between the device and environment

Yeyang Zu 2J

A isolated system is totally separate with the outside environment; however, a closed system could still exchange heat with the outside environment.

Yeyang Zu 2J

The photosynthesis reaction, 6 CO2(g) + 6 H2O(l) ⇌ C6H12O6(aq) + 6 O2(g), is endothermic. What effect will the following changes have on the equilibrium composition.
a) Water is added.

why the answer isn't no effect since water is not part of Equilibrium constand

Yeyang Zu 2J

when calculating the equilibrium constant of the chart.

question 1: In solution manuals, why does it use kPa as unit but not atm??
question 2: Even if it use kPa, why it use the percentage value like 5/100 but not just 5 (kpa)

Yeyang Zu 2J

Because NH4 has a proton to donate
NH3 can accept a proton
Therefore, based on the Bronsted principle.

NH4 is Bronsted acid
NH3 is Bronsted base

Yeyang Zu 2J

K is the equilibrium constants of the reaction, which is only changed with the temperature. However, Q is the reaction rate at any time of the reaction, which will be changed with add/remove of the substance,volume,and concentrations. In the other words, we say Q includes K; K is one value of Q in t...

Yeyang Zu 2J

usually, we said if the central atom of molecule has lone pairs, it is radical.
Why CH3 ; CH4; CH3 ; CH2; CH22 ; CH22 are all not radical??

Yeyang Zu 2J

for the molecule CH2Cl2 I think there are 2 ways to draw its lewis structure. one is that we draw the two H atom in the opposite direction; so do the Cl atoms. second one is we draw the two H atom next to each other; so do the Cl atoms. i think for the first one, the molecule is non-polar and the se...

Yeyang Zu 2J

The two lone pairs are farthest apart when they are on opposite sides of the central atom.
The AX4e2 adopt both equatorial positions and square planar arrangement.

Yeyang Zu 2J

It is different to describe Electron Arrangement and Molecular Shape?
For example, what's the Electron Arrangement and Molecular Shape of SO3 ^-2?
what's the Electron Arrangement and Molecular Shape of NH3??

Yeyang Zu 2J

Usually, the x-axis is time, and the y-axis is the concentration of reactants. It looks like the picture shown in the following links.
https://chem.libretexts.org/Core/Physic ... _Rate_Laws

Yeyang Zu 2J

Because lone paris have the strongest repulsion force to each other.

Yeyang Zu 2J

When the reaction are at equilibrium, the reaction rate and the reverse reaction rate are equal( although the concentrations could be different)
In that case, the reaction rate will increasing gradually reaching the equilibrium point instead of being equilibrium immediately.

Yeyang Zu 2J

Yes, it matters. You need to follow the Aufbau Principle, and write the orbitals from lowest energy to highest energy.

Yeyang Zu 2J

In Arctic, a bear drop into the lake and looking for help:
"HELP, i'm dissolving"
Another brown bear get there and explains:
"dude, bears are insoluble"
....
"That's easy for you to say, you are not polar....."

Yeyang Zu 2J

Kc And Kp. K and K are the equilibrium constants of gaseous mixtures. However, the difference between the two constants is that Kc is defined by molar concentrations, whereas Kp is defined by the partial pressures of the gasses inside a closed system

Yeyang Zu 2J

Amplitude is independent from frequency and wavelength.
Amplitude decides the brightness of light( the number of photons)
The higher the frequency is , the more energy light has.
Frequency and wavelength are reversely related.

Yeyang Zu 2J

A reagent is a substance or compound added to a system to cause a chemical reaction, or added to test if a reaction occurs. The terms reactant and reagent are often used interchangeably—however, a reactant is more specifically a substance consumed in the course of a chemical reaction.

Yeyang Zu 2J

You need to distinguish between rate and equilibrium position. Temperature always increases the rate of reactions (because it increases the collision frequency and the average energy of the particles reacting.) But the effect of temp on the equilibrium depends on whether the reaction is exo or endot...

Yeyang Zu 2J

Yes, it is possible! Adding more product and changing the surrounding temperature and pressure will influence the chemical equilibrium.

Yeyang Zu 2J

Add -o to the end of the anion name : for example cyanide-->cyano
YES, ammonia and chlorine are both ligands in [Co(NH3)5Cl]Cl*2h20

Yeyang Zu 2J

In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs.

Yeyang Zu 2J

Yes. It is one of the important parts that are mentioned on the outline of chapter 4.

Yeyang Zu 2J

3.87 Which do you predict to have the strongest CX bond, where X is a halogen: (a) CF4, (b) CCl4, or (c) CBr4? Explain.

if we use length strength, cf4 is the strongest.
if we use electronegativity to judge, cf4 is the weakest.

how should we solve the problem???

Yeyang Zu 2J

How to define the Ionic&Covalent Bonds if the electronegativity difference is between 1.5 to 2

Yeyang Zu 2J

You do not have to count the f-block square
for Osmium, it should be 5d6

Yeyang Zu 2J

Search found 58 matches