CHEMISTRY COMMUNITY

Simran Rai 4E

It is zero order if its concentration has no effect on the rate.

Simran Rai 4E

The rate cannot be any faster than its slowest step, therefore, it determines the rate.

Simran Rai 4E

In class, Dr. Lavelle had said to assume A=1 unless otherwise stated.

Simran Rai 4E

I think you'd only need to convert so you can have the same units across. One of the problems has mmol and mol so units for mmol were converted to mol. But the other problem had only mmol units, so no conversion was necessary. The units of the initial rate and initial concentrations should match up.

Simran Rai 4E

Here you go...

Simran Rai 4E

Thank You Lyndon!

Simran Rai 4E

That along with the making sure to know everything mentioned in the outlines.

Simran Rai 4E

Microscopic reversibility assumes that the reaction has the same pathway for forward and reverse directions.

Simran Rai 4E

As everyone said, it is cumulative, and the best preparation is to look at the outlines for each optic covered and make sure you understand all of the bullet points listed. Dr. Labels suggests practicing textbook homework problems is the best preparation.

Simran Rai 4E

You can think about it as a rate not proceeding negatively. It can be slow, or you can have a reverse rate, but a “negative” rate is not possible.

Simran Rai 4E

An inert electrode is used when there is a gas/ion electrode reaction or when both oxidized and reduced species are in the same solution, meaning there's no conducting solid.

Simran Rai 4E

This is from the website :)

Simran Rai 4E

Simran Rai 4E

Adding to that, for the third equation, when pressure is changing, you'd use w=-nRT ln (p1/p2).

Simran Rai 4E

From what I've read, they're used interchangeably.

Simran Rai 4E

If the value is negative, then it's spontaneous and favors product formation and if the value is positive, then it's non spontaneous and does not favor formation of products.

Simran Rai 4E

If Gibbs free energy is negative, that means the process is spontaneous and releases energy. Free energy is described as the energy that is available to do work.

Simran Rai 4E

When there are more microstates, there is increased entropy. This is because there is greater positional/residual vibration between molecules and that lends to greater disorder.

Simran Rai 4E

The TA or LA will usually post a practice worksheet on here for us to do before the review session, so that way they can just go through the solutions and answer any questions. But sometimes no worksheets are given and it's more note dependent based on the review session you attend.

Simran Rai 4E

Insulation only helps identify isolated systems. If there is no insulation you'd still have to determine whether the system was open or closed.

Simran Rai 4E

Yes, an increase of enthalpy means that the system was supplied with energy/heat. ^

Simran Rai 4E

Yes, you should get the same answer if you do the long method. ^

Simran Rai 4E

The standard enthalpy of formation is the enthalpy change when 1 mole of a substance is formed from its element(s). Note that all the substances should be in standard state.

Simran Rai 4E

Regarding pressure, they're both just units measurements. But if you wanted to figure out concentration you would need to use atm. For example, if you're given partial pressure but the units are in bar and you want to use PV=nRT to find concentration (with volume given), you'd need to convert to atm...

Simran Rai 4E

: This is what we got in the email

Simran Rai 4E

MadelineHlobik wrote:Does Kw=Ka*Kb and Kw=[H3O][OH]

Yes, so since Kw = 10^-14, [H30+] has to be 10^-7 and [OH-] has to be 10^-7 as well.

Simran Rai 4E

Kp should not have any units because it is an activity. ^

Simran Rai 4E

K is basically the Q, but at equilibrium.

Simran Rai 4E

Also keep in mind to discard the negative answer (of the two) you get because the concentration must always be a positive value.

Simran Rai 4E

Adding an inert gas wouldn't affect the equilibrium because the concentrations of the reactant and product would remain the same, meaning there would be no change in the equation.

Simran Rai 4E

Yes, my TA usually uses parenthesis or nothing at all when doing a problem with partial pressure. With concentration, brackets are always used.

Simran Rai 4E

904837647 wrote:Will cisplatin be apart of what we need to know on the final?

The syllabus says "Discuss well-known examples of coordination compounds used as chemotherapy drugs." so it would be a good idea to know it.

Simran Rai 4E

They are namedin alphabetical order (ignoring Greek prefixes). Ex: for pentaammine, you would look at the A in ammine rather than the P in penta.

Simran Rai 4E

Polarizability is how easy it is to pull the electron cloud of a molecule, whereas polarizing power is how good an atom is at pulling on bonding electrons. They are inversely related.

Simran Rai 4E

That's correct.

Simran Rai 4E

Polarizability is how easy it is to pull the electron cloud of a molecule, whereas polarizing power is how good an atom is at pulling on bonding electrons. They are inversely related.

Simran Rai 4E

No, if there's multiple lone pairs, their magnitude/direction can cancel out leaving you with a non polar molecule.

Simran Rai 4E

That's right, because it already has "di" in its name.

Simran Rai 4E

These practice problems and review sessions are so helpful. Thank you Lyndon!

Simran Rai 4E

You would first find the pH by calculating pH=-log[H3O+] and then subtract your answer from 14 to get the POH.

Simran Rai 4E

Lyndon had mentioned in his review session that it's good practice to do so, just to be safe. However I don't think you'd be docked points if you didn't add it.

Simran Rai 4E

Dr. Lavelle had sent out this link in an email explaining that this is a topic we'll cover in 14B.

viewtopic.php?f=60&t=38752

Simran Rai 4E

Lavelle had said in class that it would be similar to the structure of the midterm, so I'm guessing about 8 questions with multiple parts to them and maybe a couple multiple choice questions.

Simran Rai 4E

Hybridization is based on regions of electron density. Therefore lone pairs would be included.

Simran Rai 4E

Sigma bonds allow for free rotation of atoms. With pi bonds the whole molecule has to rotate, and single atoms cannot rotate freely.

Simran Rai 4E

The electronegativity values will be given to us in a problem. Otherwise, just follow the electronegativity trend for the periodic table to gauge if the values are lesser or greater than a value given.

Simran Rai 4E

The stronger the bond, the greater the repulsion strength. For example, a triple bond has greater repulsion strength than a double than a single bond.

Simran Rai 4E

It's also helpful to consider dipole moments similar to vectors. We would take into account magnitude and direction when cancelling out/ adding up vectors, and the same idea applies to dipole moments.

Simran Rai 4E

Can someone explain the difference between bent and linear? A linear shape is when the bond angles are 180 degrees exactly. This could even take place in the presence of 2 or more lone pairs depending on the amount of regions of electron density. A bent shape, however occurs when the linear shape i...

Simran Rai 4E

Also in discussion, my TA had said that paired electrons are more repulsed by lone pairs of electrons than they are by other bonded pairs of electrons. Which can also explain why they'd more readily move closer to another bonded pair in the presence of lone electrons.

Simran Rai 4E

Does the distance between the bonds effect the boiling point? Would this cause the bond to be stronger or weaker? The longer the bond the weaker it is. For instance double bonds are shorter and stronger than single bonds and triple bonds are shorter and stronger than double and single bonds. Yes, a...

Simran Rai 4E

Hilda Sauceda 3C wrote:Can anyone explain the reasoning for why 6d is true.

6d is true because the answer 10^-11 m is greater 10^-18. If it were less, then wavelength properties wouldn't be measurable.

Simran Rai 4E

Can someone help me with a quick review of zeros in sig figs? I always get confused as to which zeros count as significant and which ones do not. 1. All non zero numbers are significant. ex) 613 has 3 sig figs 2. Zeros located between non-zero digits are significant ex) 5004 has 4 sig figs 3. Trail...

Simran Rai 4E

I think that "in order for you to receive the 3 points for the discussion, you need to either post a question, answer a question or put a comment relevant to the question on a post, 3 times a week." that's what one of the TA's told me. Are the posts due by the time we have our discussion ...

Simran Rai 4E

Danny Elias Dis 1E wrote:If we were to post four times in one week, would the extra post roll over to next week's grading?

I don't think it would since the idea is to have 3 engagements weekly rather than finish them all in one week.

Simran Rai 4E

Actual yield should be given and if it is not then you cannot determine percent yield . The theoretical yield (what you'd calculate) is what would be produced in a perfect reaction with nothing lost (due to heat/ measuring errors/ etc.). The actual yield is usually an experimental value and therefor...

Simran Rai 4E

Thank you so much for this! I'm going into medicine too and hearing your insight made me feel so much better. :)

Simran Rai 4E

First take the 42.7 g of CaCO3 and convert to moles. 42.7g x (1 mol CaCO3 / 100g CaCO3 ) = 0.4273 mol CaCO3 Then take that and do mole to mole ratio and convert from mols CO2 to grams. .4273 mol CaCO3 x ( 1 mol CO2 / 1 mol CaCO3 ) x ( 44 g CO2 / 1 mol CO2 ) = 18.8 g CO2 Then take your answer and plu...

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