CHEMISTRY COMMUNITY

Wenjie Dong 2E

The oxidizing agent gains electrons and reducing agent losses electrons. A easy way to remember this is that Oxygen usually (not always!) acts as the oxidizing agent in redox reactions and it gains electrons during redox reactions.

Wenjie Dong 2E

You could refer to activity series of metals. For example, https://www.thoughtco.com/activity-seri ... als-603960.

Wenjie Dong 2E

No, you don't have to. It may be canceled out or doesn't never needed to balance the equation.

Wenjie Dong 2E

E_cell=-0.44 V-(-0.74 V)=0.30V, and then use the equation mentioned above to calculate K.

Wenjie Dong 2E

I think it's out of the sig figs problem.

Wenjie Dong 2E

Negative order means that increasing the concentration slows down the reaction. I believe it happens when products' concentrations affect the reaction rate.

Wenjie Dong 2E

There is no need to do so unless other calculation is needed.

Wenjie Dong 2E

It's because CO2 is the other reactant in this reaction. Since it does not occur in the reaction of NO2, there must be a subsequent reaction that involves CO2.

Wenjie Dong 2E

I think graphs will be given or the correlation will be explained.

Wenjie Dong 2E

It's because the unit of the reaction rate is always the same.

Wenjie Dong 2E

Same question.

Wenjie Dong 2E

I guess you should always reverse the less reactive one.

Wenjie Dong 2E

Agar with solutions of high concentration.

Wenjie Dong 2E

Agree. The substance loss electrons is oxidized and that gain electrons is reduced.

Wenjie Dong 2E

As for other chemical experiments, there is always less an efficiency for actual operations than that by calculations.

Wenjie Dong 2E

Same question!

Wenjie Dong 2E

Christina Bedrosian 1B wrote:This formula is true for instances of isothermal expansions since having deltaT=0 (no change in temp), then deltaU (internal energy) would be 0 and since deltaU=q+w, then q would equal -w

Agree.

Wenjie Dong 2E

Bansi Amin 1D wrote:So the heat was transferred to make up for the change in energy in the system?

Heat is transferred because of a temperature different. The work is done by the system through giving off heat and the work is done to the system by increasing its heat.

Wenjie Dong 2E

Kyung_Jin_Kim_1H wrote:Conservation of energy in the universe.

(I didn't even think of elaborating...)

Same.

Wenjie Dong 2E

Abigail Yap 2K wrote:Hi,

Delta S is the change in entropy and delta U is the change in internal energy.

Agree.

Wenjie Dong 2E

Lily Guo 1D wrote:Not necessarily, but delta G = 0 does mean that the reaction is at equilibrium.

Agree.

Wenjie Dong 2E

Wenjie Dong 2E wrote:"It measures the maximum or reversible work that may be performed by a thermodynamic system at a constant temperature and pressure. (isothermal, isobaric)"

from Wikipedia

Wenjie Dong 2E

"It measures the maximum or reversible work that may be performed by a thermodynamic system at a constant temperature and pressure. (isothermal, isobaric)"

Wenjie Dong 2E

Not sure. But an increase in the amount of gas increases the moles of molecules and thus increases the possibilities of microstate arrangements, which leads to higher entropy.

Wenjie Dong 2E

There is no such thing as negative entropy. The negative delta entropy means a decrease in disorder.

Wenjie Dong 2E

Ryan Sydney Beyer 2B wrote:I'm not too certain that we will have to calculate the number of microstates for a specific molecule, but rather if the molecule can be in place A or place B. I think it'll more like probability in place A vs. place B and that is the number of microstates.

Agree.

Wenjie Dong 2E

There is no change in internal energy in the system when delta U=0.

Wenjie Dong 2E

Heat capacity is an extensive property because for one substance it changes when the amount of substance changes. Specific Heat Capacity and Molar Heat Capacity are intensive property because they are identical for one substance, independent on the amount.

Wenjie Dong 2E

Just always subtract the initial U from the final one no matter which one is larger.

Wenjie Dong 2E

When there is no word done to the system, the change of internal energy is the same as the heat change. When there is no heat exchange, the change of internal energy is equal to the work done.

Wenjie Dong 2E

The equations should be:
N2 + O2 --> 2NO
2NO + O2 --> 2NO2
-----------------------
N2 + 2O2 --> 2NO2

Wenjie Dong 2E

Hess's Law is more macroscopic while bond enthalpies method is more microscopic. Hess's Law focuses merely on the heat changes during reactions and presents the conclusion that "the total enthalpy change for the reaction is the sum of all changes." Bond enthalpies method concentrates on th...

Wenjie Dong 2E

It means the form when the element has the least energy.

Wenjie Dong 2E

If not given, it's usually resulted from the change in volume.

Wenjie Dong 2E

Same question!

Wenjie Dong 2E

Christina Cen 3E wrote:pkb = 14 - pka
The lower the pkb is, the stronger the base, so the higher the pka = smaller pkb = stronger base

I agree with your explanation!

Wenjie Dong 2E

Just remember lone pair has stronger repulsive force and results in relatively larger bond angles around it.

Wenjie Dong 2E

I happened to see a picture that indicates it's two oxygens attached to one carbon but I'm not sure.

Wenjie Dong 2E

It will. For example, NH3 has a lone pair in N and its hybridization is sp3.

Wenjie Dong 2E

Electrons are less stable in long pairs and thus have higher energy. Higher energy causes higher repulsion.

Wenjie Dong 2E

Cis- is for atoms that are next to each other, while trans- is for those are opposite to each other.
For example, PtCl2(NH3)s, we use "cis-" for the molecule with the structure of Cl next to each other and "trans-" for Cl opposite to each other.

Wenjie Dong 2E

I guess it is, but we might not go that further into that.

Wenjie Dong 2E

I agree with Ryan.

Wenjie Dong 2E

Subtract total valence electrons from electrons needed to form octets structure in all atoms. Half that number we get, and then use the answer to determine whether we need single, double or triple bonds.

Wenjie Dong 2E

We can have many orbitals (s, p, d, f) under one subshell.

Wenjie Dong 2E

StephanieDoan3B wrote:All three orbitals have the same energy, and the electron will fill any of them first. We designate that px is filled first, then py, and pz because of convention.

I agree. So there will be a second electron on any of the orbit only if px, py, and pz are all filled with one already.

Wenjie Dong 2E

I agree with the above two answers. Both yes.

Wenjie Dong 2E

It is better to convert to the most used units.

Wenjie Dong 2E

I guess we don't need to.

Wenjie Dong 2E

Julie Steklof 3C wrote:The energy required to ionize an electron is the same as the energy required to remove an electron.

I agree.

Wenjie Dong 2E

Mia Navarro 1J wrote:the shift of an electron's flight with respect to a photon's energy being shot at it.

What is this experiment? Can u explain more of it?

Wenjie Dong 2E

Can anybody explain Electric Field and Magnetic Field of Light for me?

Wenjie Dong 2E

1. Use the molecule formula C10H7OH to calculate mass percentage composition of C, H, O 2. Get the simplest ratio of mass of C, H, O in C10H7OH (C:H:O=15:1:2) 3. Get the percentage of O in C10H7OH in the sample using the ratio above (H : O = 5.20% : ? = 1:2 --> ? = 10.40%) 4. Add up the percentage o...

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