CHEMISTRY COMMUNITY

Dane_Beasley_1E

Yes over a very long amount of time because of how high the activation energy is for the reaction.

Dane_Beasley_1E

The units for reaction rates are molarity over time. For the different orders the units are:

0th = molL−1s−1
1st = s−1
2nd = L mol−1s−1

Dane_Beasley_1E

A more negative reduction potential makes worse oxidizing agents and vise versa.

Dane_Beasley_1E

Both ways are correct, but using a fraction is useful when you want the product to have 1 mol.

Dane_Beasley_1E

This is because of equilibrium. Since most reactions are reversible, if too much of a of a product forms it will begin the reverse reaction to maintain equilibrium.

Dane_Beasley_1E

Only thing that can cause k to change is temperature.

Dane_Beasley_1E

It can be used to find the enthalpy, temperature, or the K.

Dane_Beasley_1E

To calculate delta S(surrounding) you would divide the deltaH(system) by temperature.

Dane_Beasley_1E

Here the system would be doing the work because it has to change, therefore the work is negative.

Dane_Beasley_1E

When delta G is negative (or spontaneous), the fuel cell is thermodynamically feasible.

Dane_Beasley_1E

Yes because aqueous solutions are included for Kc.

Dane_Beasley_1E

Salts can be acidic, basic, or neutral depending on the anions and cations. NaCl is a neutral Salt for example.

Dane_Beasley_1E

An endothermic reaction is when the system is absorbing heat. The endothermic reactions in relations to phase changes are: Solid to Liquid Liquid to Gas Solid to Gas An exothermic reaction is when the system is releasing heat. The exothermic reactions in relations to phase changes are: Liquid to Sol...

Dane_Beasley_1E

Enthalpy refers to heat released or absorbed while heat describes a transfer of energy.

Dane_Beasley_1E

A phase change is when one state of matter changes into another state of matter. For example, when an ice cube melts into water that would be a phase change from solid to liquid.

Dane_Beasley_1E

Vapor and gas are interchangeable terms and are used for the same thing.

Dane_Beasley_1E

When reversing the reaction you would use the reciprocal of K.

Dane_Beasley_1E

H2O is assumed to be a liquid unless stated otherwise. You would disregard it in K.

Dane_Beasley_1E

Temperature is the only factor that will affect K.

Dane_Beasley_1E

K refers to the Kp pressure constant and Kc is the concentration constant.

Dane_Beasley_1E

If the K value is less than 10^-4 and/or the % ionization is 5% or lower than it would make x negligible.

Dane_Beasley_1E

When the k value is less than 10^-4 then you can use that approximation.

Dane_Beasley_1E

That is true for all monoprotic acids.

Dane_Beasley_1E

In order to calculate percent ionization, you would take the concentration of H+ at equilibrium(x value) and divide it by the initial concentration of the acid. Multiply this number by 100 to get the answer.

Dane_Beasley_1E

For an acid, when pH>pKa, it is charged. When pH<pKa it is neutral.

Dane_Beasley_1E

Bars and atm are the preferred units.

Dane_Beasley_1E

In order to choose the right R you would make sure that the units for pressure and volume match the question.

Dane_Beasley_1E

Solids do not have concentration because their volume is fixed and they do not dissolve in a solution.

Dane_Beasley_1E

A large K would constitute as anything above 10^3 and a small K would be anything lower than 10^3.

Dane_Beasley_1E

I don't believe that we will be using non-ideal gases in this course as it is not mentioned in the syllabus.

Dane_Beasley_1E

A Bronsted base "borrows" a proton whereas a Bronsted acid donates a proton.

Dane_Beasley_1E

Water is amphoteric, so it can act as both an acid and base. This means it can both accept and donate an proton.

Dane_Beasley_1E

You would want to use Avogadro's constant when converting moles into atoms/electrons/particles. You would also conversely use when converting from atoms/electrons/particles to moles.

Dane_Beasley_1E

Yes, mass should be converted into kg as it is the SI unit.

Dane_Beasley_1E

You would divide by Avogadro's number when converting from moles to atoms/molecule, and you would multiply by Avogadro's number when converting from atoms/molecule to moles.

Dane_Beasley_1E

When naming a coordination compound you would first want to name the ligands and then the metal ion. You would also want to make sure they are in alphabetical order.

Dane_Beasley_1E

Keeping track of the states of matter is recommended as it would help you in higher courses of chemistry.

Dane_Beasley_1E

I would recommend changing the sig figs at the end of the problem. This way you could not mess up the accuracy of your solution.

Dane_Beasley_1E

I would do all calculations first while maintaining all decimal places possible. Then after the solution is found, I would start looking to see what the sig figs would need to be.

Dane_Beasley_1E

Thank you very much! I found this video super helpful.

Dane_Beasley_1E

Yes you are correct. The reason there is a decimal after the 350. is to indicate 3 Sigfigs and not 2.

Dane_Beasley_1E

Yes, you have it right. When mulitiplying you would use the least number number of Sigfigs and when adding you would use the least number of Sigfigs after the decimal.

Dane_Beasley_1E

When there is a decimal point the trailing points are counted. Therefore, 20.00 has 4 SigFigs.

Dane_Beasley_1E

We should always use SigFigs in our answer I believe. It's handy in most situations.

Dane_Beasley_1E

The decimal makes 40. have two sigfigs. Without the decimal it just has one sigfig.

Dane_Beasley_1E

H can not be a central atom because it can only form one chemical bond.

Dane_Beasley_1E

A Lewis acid would accept electrons while a Lewis base would donate electrons.

Dane_Beasley_1E

The unit mmol is a millimole. It is 10^-3 of a mol.

Dane_Beasley_1E

I agree with many of the people in this post. Keeping it in scientific notation will be best for consistency in calculations, and it keeps the answer in sigfigs.

Dane_Beasley_1E

I don't believe there are any more modules for future topics. However, I do agree that they are very helpful in going back and studying material.

Dane_Beasley_1E

In order to convert meters into picometers you would multiply by 1 * 10^-12.

Dane_Beasley_1E

The answer is false because increasing intensity increases the number of photons. Energy only increases when frequency increases.

Dane_Beasley_1E

Yes, I do believe that the speed of light will always be represented as the constant c.

Dane_Beasley_1E

Your equation looks right, so I would make sure you put everything into your calculator right. I would also make sure you converted the frequency into wavelength right using lambda = c/f. Then change the wavelength into nanometers.

Dane_Beasley_1E

The equation E=hv gives the energy per photon. So that's why it is 100E. Wavelength and frequency are not affected because each photon would have its own frequency and wavelength. Since each photon has the same energy, they would have the same wavelength and frequency keeping it a 1.

Dane_Beasley_1E

The italicized v is actually the Greek letter nu and is used for frequency. When working with velocity it is just a regular v.

Dane_Beasley_1E

In order to solve this problem, you would need to use the de Broglie equation. The problem is asking for the velocity of each so you would need to isolate velocity.

wavelength = h/mv

v=h/m(wavelength)

Dane_Beasley_1E

You have to make sure that the wave ends in the same position where it begins. For example, if the wave ends at the midway point going up then the beginning of the wave would have to start at the midway point going up. It would have to be continuous if connected.

Dane_Beasley_1E

The Balmer series ends at n=2 and the Lyman series ends at n=1. The Lyman series deals with UV light and the Balmer series deals with visible light. This is helpful when you don't know exactly where it ends, but it gives you what kind of light you are dealing with.

Dane_Beasley_1E

I don't believe that we will be asked a question about the definition of those words exactly. However, it will probably be useful to know what these words mean because they could be used in a question on the test.

Dane_Beasley_1E

We will not have to memorize elements on the periodic table. We will given the periodic table on Lavelle's website to use during tests.

Dane_Beasley_1E

Rounding those numbers to 8.0 and 5.0 would be correct. Zeroes following a number 1-9 count as a significant figure when there is a decimal.

Dane_Beasley_1E

My TA let us know that we can print out the constants and equations sheet on Professor Lavelle's website for the test. We can also print out the periodic table on his website to use on the test.

Dane_Beasley_1E

Yes, (OH)2 would be the same as writing O2H2. Adding parenthesis just groups them together and simplifies the term.

Dane_Beasley_1E

Increasing the intensity will only increase the number of photons, but not the energy. So increasing intensity will not give it enough energy to eject electrons. However, increasing the frequency will increase the energy of the photon. Therefore, increasing frequency can give it the energy needed fo...

Dane_Beasley_1E

I think the best way is just to do 10^x. It also keeps it in scientific notation for sigfigs.

Dane_Beasley_1E

In writing scientific notation, I would use the * 10^x notation. I feel like the E6 is great for typing things into the calculator tho.

Dane_Beasley_1E

I believe that 2.8 is close enough to 3 to round up. I believe that the bench marks are whole numbers, .25, .33, .5, .67, and .75. So with a 2.8 you would not round down to 2.75, it makes sense to just round up to 3.

Dane_Beasley_1E

For Balancing Rxns, I usually try to balance metals first. Then I would balance carbon. If hydrogen and oxygen are in the equation, I would balance hydrogen next and oxygen last always. I try to stick to this most of the time.

Dane_Beasley_1E

I had a question about Significant Figures with decimals. When there is a decimal, do all leading zeroes not count towards SigFigs? For example, would 0.0840 be 5 SigFigs or 3 SigFigs?

Thank you!

Dane_Beasley_1E

Hi Alessia! In order, to convert Kg to g you have multiply your number by 1000. For example, if you have 25 Kg then to convert that to grams you would multiply 25 by 1,000. Therefore you would get 25,000 grams. I hope this helps!

Dane_Beasley_1E

Thank you for the advice!

Dane_Beasley_1E

I totally converted liters to milliliters wrong, thank you guys!

Dane_Beasley_1E

The problem is, "If 3.16 g of CuNO3 is dissolved in water to make a 0.400 M solution, what is the volume of the solution in millimeters?" First, I found the molar mass of CuNO3 and got 125.553 g/mol. I then divided 3.16g by 125.553g/mol to get 0.0252 mol CuNO3. I then found the equation fo...

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