CHEMISTRY COMMUNITY

Michelle Nwufo 2G

So, if volume does not change, then work is equal to zero in a bomb calorimeter, right?

Michelle Nwufo 2G

Could someone briefly list the different half-life formulas for each order of reactions?

Michelle Nwufo 2G

The order of a cell diagram would have a structure of: anode|gas, liquid| aq. molecule || aq. molecule|gas, liquid|cathode. Everything to the left of the || is the oxidation reaction while everything to the right of the || is the reduction reaction. H+ if it is in aqueous state would be in the sect...

Michelle Nwufo 2G

Can someone please reiterate the order of a cell diagram and where H+ goes?

Michelle Nwufo 2G

How do you calculate the pH of a cell, using the Nernst equation? Or can we use the standard potential?

Michelle Nwufo 2G

Cole Doolittle 2K wrote:H+ is included in the cell diagram, but H2O (l) and electrons are not.

Also, is the H+ state aqueous?

Michelle Nwufo 2G

Is the sign for rate of formation of products and rate of consumption of reactants always positive, if so why?

Michelle Nwufo 2G

MichaelMoreno2G wrote:As mentioned above, Delta G would be less than zero because the reaction is spontaneous.

But how do you determine whether the reaction is spontaneous or not?

Michelle Nwufo 2G

The rate-determining step is the slowest step in a reaction mechanism. Because it is the slowest, it determines the rate of the overall reaction. In a reaction with a slow initial step, the rate law will simply be determined by the stoichiometry of the reactants. How do you determine whether a step...

Michelle Nwufo 2G

Also, how do you know when to add a conducting solid to the cell diagram?

Michelle Nwufo 2G

So when it is reversed, does the standard reduction potential become negative?

Michelle Nwufo 2G

I think that you also have to make sure that the charges on both sides of the reaction is balanced. So even if the amount of atoms on both sides is balanced, you still need to balance the charge.

Michelle Nwufo 2G

I’m assuming it is when you want to find the change in gibb’s free energy, and you are given the change in enthalpy and change in entropy of the reaction. But I could be wrong.

Michelle Nwufo 2G

A reaction is spontaneous when the delta G value is negative. This indicates that the given reaction is favorable in that direction and will lead to a release in free energy, meaning that reactants have more free energy to do work than the products. Why does a negative value for delta g indicate th...

Michelle Nwufo 2G

Also, is there a correlation between state functions and extensive Properties?

Michelle Nwufo 2G

I am also confused, I recall the professor saying something about Gibbs Free Energy being leftover energy, but I just don’t remember from what.

Michelle Nwufo 2G

Are we required to memorize all the different values of r?

Michelle Nwufo 2G

Which of the reactions requires you to take the integral of the change in volume when calculating work?

Michelle Nwufo 2G

Also, it’s kind of confusing why work and degeneracy have the same constant. Are they somehow related?

Michelle Nwufo 2G

Celeste 1I wrote:If it is not otherwise stated, yes you assume the pressure is equal to 1 atm.

Why do we assume that pressure is equal to 1 ATM when the pressure is constant?

Michelle Nwufo 2G

Mukil_Pari_2I wrote:For the reaction, q would be negative if that helps.

I do not think this is correct because if a reaction releases heat then q will be negative-the reaction is losing the energy. On the other hand, if a reaction requires heat then q will be positive because the reaction is gaining the energy.

Michelle Nwufo 2G

An example of a closed system is a beaker that can allow energy to exchange with the surroundings but matter doesn't exchange with the surroundings. An example of a closed system would be a really well-insulated coffee mug that doesn't allow energy or matter to exchange with surroundings. Would the...

Michelle Nwufo 2G

In the example professor did in class, he added the reactants and products of the two reactions for the formation of nitrogen oxide and its reaction with oxygen, along with their enthalpies.

Michelle Nwufo 2G

You can calculate the standard reaction enthalpy by using the standard enthalpy of formation of all products and subtract the standard enthalpy of formation of all reactants. Can you briefly explain what the standard enthrall of formation of an element is? I know that the element has to be in its m...

Michelle Nwufo 2G

Yes, the steps are exactly the same as calculating without a salt (though the calculations might be a bit more difficult). In these types of problems, the thing to note is that the initial concentration for the salt (or product of the salt) will not be zero. Therefore, the equilibrium concentration...

Michelle Nwufo 2G

It's also important to remember that we are not saying that X=0, but that it is a small enough number so that when subtracted from a larger number, that larger number remains relatively the same amount.

Michelle Nwufo 2G

It does not matter, as you will get the same answer either way. However, I am confused on how to determine which reaction will be favored when calculating the positive and negative changes in molarity when constructing the ICE table. Does anyone happen to know?

Michelle Nwufo 2G

I am also confused on not just determining if something is an acid or base, but determining whether or not something is a WEAK acid or base. Can any of you clarify please?

Michelle Nwufo 2G

Yes, that is true and when q>k, the reverse reaction is favored and there are more products, resulting in the production of reactants. However, I am having a hard time understanding why the value of Q matters when determining which direction a reaction will proceed.

Michelle Nwufo 2G

Also, regarding the equilibrium constant equation, donthe concentrations of the reactants and products not change at equilibrium, or do only their ratios not change, or is it both?

Michelle Nwufo 2G

When the chemical equilibrium is reached, does the composition of the reaction mixture remain constant because the forward and reverse reactions are occurring at equal rates?

Michelle Nwufo 2G

Liset Rivera 3A wrote:calculating equilibrium shouldn't be on the final. However, you should know the conceptually know and understand it.

Could you explain the conceptual meanings of Ka and Kp?

Michelle Nwufo 2G

How do I determine whether the hydrogen will be attached to the central atom or not in acid Lewis bases? Is there a specific rule?

Michelle Nwufo 2G

Why is hIO weaker than hclo, even though Iodine has a larger atomic radius than chlorine?

Michelle Nwufo 2G

Are conjugate acids the same thing as Lewis acids? If not, what is the difference?

Michelle Nwufo 2G

I think you also have to consider whether there are single bonds, double bonds, or triple bonds because if the atom in the ligand contains a pi bond then it won’t be able to bend and bind to the same central atom simutaneously.

Michelle Nwufo 2G

If the ligand is neutral, meaning it has no charge, how do we find the oxidation number of the metal?

Michelle Nwufo 2G

Following up with this question, why does high covalent character mean high boiling point?

Michelle Nwufo 2G

Can someone explain why so32- has a greater bond length than so2-?

Michelle Nwufo 2G

So resonance creates a more stable bond, but how do lone pairs affect the strength of the bonds within a molecule?

Michelle Nwufo 2G

Can someone explain to me why NF3 is a polar molecule? Is it because the lone pair on the central atom distorts the shape of what would have been a tetrahedral, making the molecule asymmetrical?

Michelle Nwufo 2G

Basically, the dipole moment occurs whenever there is a more electronegative molecule within a covalent bond. For example, h2o is a polar molecule because oxygen is way more electronegative then hydrogen; thus the dipole moment occurs as the hydrogen shares its electrons with oxygen and gets a sligh...

Michelle Nwufo 2G

Do you guys know if on the test, when they ask for us to find shape of a molecule, should we assume they are referring to the geometry?

Michelle Nwufo 2G

I’m also confused, I don’t quite understand why Sr 2+ has a greater polarizing than Rb+, even though they both become krypton when their electrons as removed.

Michelle Nwufo 2G

Can someone please confirm that ionic character is the difference in electronegativity between two atoms? Also can ionic character and polarity be used interchangeably?

Michelle Nwufo 2G

Going off defining covalent character, why are compounds that have a bond with high covalent character less soluble in water?

Michelle Nwufo 2G

For number 5, I keep getting .127 M after setting the problem up like (.211 M)(.150 L) = M2(.250 L). But in my notes, I believe Lyndon got 1.69 x 10^-2. I was wondering if anyone knows what I am doing wrong. Thanks! Hi! Since the problem stated that only 20ml was removed to the 2nd flask, you put 0...

Michelle Nwufo 2G

So, is the number of bond lengths determined by the number of different bonds (single bond, double bond, triple bond) there are?

Michelle Nwufo 2G

Can anyone explain how to calculate the radial and angular nodes and their correlation to quantum numbers? Does L equal the number of angular nodes, and does n-1 equal the number of radial nodes?

Michelle Nwufo 2G

So delta p also represents the uncertainty of the velocity times the mass. Therefore if we are given the uncertainty of a specific mass and delta x, we can calculate delta v?

Michelle Nwufo 2G

I believe the diameter of the atom is twice of "delta x," it looks like the question wants you to put 1/2 of that diameter into the uncertainty equation in delta x and solve of velocity. So, to confirm that I am solving this problem correctly, whenever the diameter is given, that represen...

Michelle Nwufo 2G

So, mass is always represented in kilograms and velocity in meters per second?

Michelle Nwufo 2G

I know that he photoelectric effect shows that increasing the intensity of light does not increase the amount of ejected electrons if the energy of the light is below threshold, but what was the original purpose of the photoelectric experiment?

Michelle Nwufo 2G

Just to be sure, kinetic energy is the same thing as the amount of excess energy left once the electron is released? Also, work function also means the amount of energy required to eject an electron? I’m just wondering because I’ve been seeing them being used interchangeably?

Michelle Nwufo 2G

Just to clarify, an electron can be ejected from a metal surface if the energy of the photon is greater than the energy required to remove the electron or if the energy of the photon is equal to the energy required to remove the electron?

Michelle Nwufo 2G

Nano means one billionth i.e. 10^-9 so 1 nanometer is a billionth of a meter. To convert meters to nanometers, you should multiply by 10^9 instead of divide. Do u mean divide, instead of multiply because I think they originally multiplied and got the wrong answer. I divided, but I’m not sure if I d...

Michelle Nwufo 2G

Because energy and frequency are proportional, if the question asked to arrange the photons in order of increasing frequency, would the answer remain the same?

Michelle Nwufo 2G

So, just to break it down for you... If you look at (a) you’ll notice that this can’t be the answer because speed is constant. The speed of the radiation wouldn’t decrease. For (b) the wavelength of the radiation wouldn’t decrease since frequency and wavelength are inversely proportional. (D) isn’t...

Michelle Nwufo 2G

And just to confirm, the amount of sig figs in our answer should always be equivalent to the lowest amount of sig figs given in the data of our problem?

Michelle Nwufo 2G

What happens when you are dividing the given molar mass by the molar mass of the empirical formula in order to find the molecular formula and get a number like 2.18. Do i just round this to 2 and multiply the empirical formula by 2?

Michelle Nwufo 2G

I am in need of clarification on how to go about calculating the molar mass of a metal , given its percent composition within a compound formula, but not given the specific element. How do we calculate its molar mass, if we do not know the element. Should we use Avogadro's number?

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