CHEMISTRY COMMUNITY

Alan Cornejo 1a

What do you call a tooth in a glass of water? A one molar solution!

Alan Cornejo 1a

Carbon and hydrogen went on a date. I heard they really bonded

Alan Cornejo 1a

Why does a hamburger have less energy than steak? Because it's in the ground state!

Alan Cornejo 1a

Old chemists never die. They just stop reacting

Alan Cornejo 1a

hahahahaha thanks for that !

Alan Cornejo 1a

Nathan Rothschild_2D wrote:They are not the same thing, just related
W=X^n
Where W= Degeneracy, X=the number if possible microstates, n=number of available particles

This is correct, they are two distinct things but they can be related with an equation

Alan Cornejo 1a

Jiyoon_Hwang_2I wrote:You should calculate Q and K and if Q < K then the reaction is product favored and will shift to the right

This is correct you would look at the two reactions individually, and determine Q's value relative to K

Alan Cornejo 1a

Your units in the end, end up canceling eachother out with the exception of kj which is what you are calculating for deltaG.

Alan Cornejo 1a

KaleenaJezycki_1I wrote:Why is this??

I also wonder this, I've been researching and googling but there only the conclusions that nothing can survive in a highly alkaline environment, but nowhere it really explains how.

Alan Cornejo 1a

In addition to being able to see our grades, does anyone also know if we will be able to review our answers? I would like to see the questions I got wrong. How will we be able to see these? Is he releasing the final exams online? We'll be able to see specifically what we missed because we took the ...

Alan Cornejo 1a

The grades will probably be done and posted by the end of this week

Alan Cornejo 1a

^^ I agree. The fact that he said he would upload chemistry community grades on thursday I'm assuming means he's going to upload all the other grades too. Especially since the final was multiple choice it shouldn't take long for him to grade and upload Also agree, the final was graded on the spot s...

Alan Cornejo 1a

Thank you professor for being quite possibly the most caring and genuine teacher I have ever met. Your determination for students to understand the material and do their best portrays just how much you care for your students !

Alan Cornejo 1a

This is correct, although the only real curve is that you need 250 points to pass the class with a c-

Alan Cornejo 1a

The proton is not speaking to the other proton, he’s mad atom

Alan Cornejo 1a

Two molecules are walking down the street and they run into each other. One says to the other, "Are you all right?"
"No, I lost an electron!"
"Are you sure?" "I'm positive!"

Alan Cornejo 1a

Use kelvin and make sure your units match up.

Alan Cornejo 1a

I would say there are three main ones, ∆G° = ∆H° - T∆S°and ∆G° = - RT ln K and G=-nFE . All of these are given on the constants sheet, and so being able to derive these equations and manipulate them to find them to your suitable variable you need to calculate is what you will most be needing to do

Alan Cornejo 1a

When your deltaG value is negative you will have a spontaneous reaction, when it is positive it will not be. When a reaction is exothermic it is spontaneous, and when is is endothermic it is not. Exothermic reactions have negative deltaG values and endothermic have positive deltaG values. Hope this ...

Alan Cornejo 1a

A typical rule of thumb is to just be aware of the biological examples he gave in lectures, any other examples that he doesnt mention we wont need to memorize or know specifically.

Alan Cornejo 1a

For this question since the answer choice a has reactants and products all as solids in the same phase, there will be almost not entropy change.

Alan Cornejo 1a

An open system is a system that freely exchanges energy and matter with its surroundings. A closed system is a system that exchanges only energy with its surroundings, not matter.An isolated system does not exchange energy or matter with its surroundings.

Alan Cornejo 1a

An isolated system has energy that remains constant, and is exposed to a constant pressure

Alan Cornejo 1a

ayushibanerjee06 wrote:Yes you add all of them up at the end. If you reverse a reaction, it is negative. You multiply/divide H by whatever you manipulate the reaction. Remember that you can do this because enthalpy is a state function!

This is correct thank you for the clarification.

Alan Cornejo 1a

When work is done b the system against the surrounding the value is negative. When work is being done ON the system by the surrounding such as an increasing external pressure, then work is positive.

Alan Cornejo 1a

Expansion can be determined if work is done by the system at a constant pressure, so we find that the system expanded against the external pressure.

Alan Cornejo 1a

Manav Govil 1B wrote:I used https://www.thoughtco.com/intensive-vs- ... ies-604133 when I was studying for my exam.

Thank you for the link, it was very hepful

Alan Cornejo 1a

Regular calorimeters is done using a constant pressure, while the difference in bomb calorimeters is that they are done at constant volume.

Alan Cornejo 1a

For the ideal gas law it shoudlnt be used for that intended purpose, but for the issue you propose it would be suggested to using the m1v1= m2v2 equation

Alan Cornejo 1a

Kp is used in the event that you products and reactants all exists in a gas phase. Therefore we use the partial pressures of the gases and make sure the units we use as a result also take that into inclusion. For Kc we use that when we are trying to determine concentration rather than the pressure.

Alan Cornejo 1a

When decreasing the volume of a reaction, you also increase the pressure. Using le chatliers principle we find the reaction will shift towards the side that has fewer moles of gas, which in this reaction is the products as there are only 2 mols of gas compared to three on the reactants side.

Alan Cornejo 1a

The total enthropy is described using the equation total entropy is equal to the entropy of the system and surrounding added to eachother. For tempurature change including entropy we use the equation, deltaG = deltaH - T*deltaS, if our value of deltaG is negative then our reaction is spontaneous, if...

Alan Cornejo 1a

In order for a bond to break there must have a source of energy to break that bond, and so with the formation of bonds because is typically an exothermic reaction, heat is released

Alan Cornejo 1a

Delta H is equal to q when no work is done onto a system, such as a constant pressure

Alan Cornejo 1a

Enthalpy (ΔH) is the measure of heat released or absorbed at a constant pressure. q is just heat under any conditions. ΔH would be equal to q only when the heat is released or absorbed at a constant pressure. This is the correct answer, another way to think about it is that you can use the two term...

Alan Cornejo 1a

You can find the enthalpy by using the standard enthalpies of formation in the back of the textbook. Use equation deltaH = sum of deltaH products - sum of deltaH reactants to find the delta H value. Also a reminder that when using the sum of the deltaH products and reactant it is important to recog...

Alan Cornejo 1a

The answer is A because we first realize that chnage in gibbs free energy is equal to the change in enthalpy subracted by the product of temperature and the change in entropy or, ∆G= ∆H-T∆S. We also know that ∆G= ∆H when ∆S is approximately 0. Because answer choice has reactants and products all in ...

Alan Cornejo 1a

answer choice B is the most concentrated solution thus consisting of the least amount of water of the answer choices. Because water has a high specific heat capacity, meaning it takes more energy to heat, if we want to have the highest temperature change, it would be ideal if we can limit as much wa...

Alan Cornejo 1a

Using kelvin is most advisable as it is an easy conversion, and it allows for the matchup of all the right units for your equation.

Alan Cornejo 1a

One way to determine if the reaction will proceed right or left is by comparing to equilibrium value to the reaction quotient value. If your reaction quotient (Q) is less than K than your reactants will continue to react and your reaction will proceed to the right towards the products and vice versa...

Alan Cornejo 1a

I’m reading a chemistry book about helium.
I can’t put it down.

Alan Cornejo 1a

I know a guy who cooled himself to -273.15C.

He was 0k.

Alan Cornejo 1a

Do you know a good chemistry joke?
No sorry, all of them argon

Alan Cornejo 1a

Two atoms are walking down the street. Says one atom to the other, “Hey! I think I lost an electron!”
The other says, “Are you sure?”
“Yes, I’m positive!”

Alan Cornejo 1a

A neutron walks into a restaurant and orders a couple of drinks. As she is about to leave, she asks the waiter how much she owes. The waiter replies, “For you, No Charge!”

Alan Cornejo 1a

Man: I wish I was the Enzyme DNA Helicase.
Woman: Why?
Man: So I could unzip your genes.

Alan Cornejo 1a

Thank you

Alan Cornejo 1a

Yes we would assume it is reversible as most chemical reactions are reversible, usually from the context you can infer from the question such as it stating that the pressure is constant or not constant,

Alan Cornejo 1a

Does anybody know if the midterm will be covering molar internal energy with the likeliness of translational and rotational energy ?

Alan Cornejo 1a

The atom thats least electronegative should be the central atom, if you have two I would assume it would be best to create the shape by simply drawing the structure according to the appearance in the chemical formula.

Alan Cornejo 1a

If the molecule or atom has a negative or positive charge it is best to portray so, if it is neutral there is really no need.

Alan Cornejo 1a

405268063 wrote:Yup, if there are no cations or anions attached to it, you also add "ion" at the end of the name.

THis is correct, if not cations or anions seem to from with it, the ion name will be added

Alan Cornejo 1a

the least electronegative atom is typically the central molecule. hydrogens will always be on the outside since they can only form one bond. make sure to know specific trends (such as how carbon always wants to make 4 bonds to keep the FC at 0) This is correct, usually the atom thats least electron...

Alan Cornejo 1a

Chlorine is one of the few atoms of which can also break the octet rule allowing it to expand its shells and hold more than 8 electrons

Alan Cornejo 1a

Pi bonds occur with double bonded or triple bonded atoms, while sigma bonds occur with single bonds. Sigma bonds are going to be weaker and longer bonds than a pi bond.

Alan Cornejo 1a

For the simple fact that protons of mass, they cannot reach the speed of light, objects with mass cannot travel at the speed of light

Alan Cornejo 1a

Helium walks into a bar,
The bar tender says "We don't serve noble gasses in here."
Helium doesn't react.

Alan Cornejo 1a

In order to pass the class you need at least 250/500 points to pass with a C-. The rest of the grades as far as A's and B's I believe will be graded on a curve dependent on the overall/average score of students.

Alan Cornejo 1a

Being able to be in a relaxed state of mind is the best thing you can do for your self, this can be done through reviewing days ahead in advance to avoid cramming and using the last day to do an easy guide over and to relax and have fun, as having fun and laughing is proven to enhance neural pathway...

Alan Cornejo 1a

Can someone help me understand why we use the Rydberg equation? The Rydberg equation is used to calculate the energy of an electron at a certain principle quantum level of an atom. We'll usually use it in problems where we're asked to calculate the change in energy, frequency, or velocity that occu...

Alan Cornejo 1a

London dispersion forces are weaker than the other intermolecular forces and therefore does not exert high polarizability

Alan Cornejo 1a

You would look for ligands that act as polydentate. For example, if the coordination compound has ethylenediamine or en, you would know that it is chelating since en is a bidentate. This is correct, as long as you identify the ligands that have two or more atoms capable of binding to a central meta...

Alan Cornejo 1a

I'm not entirely sure, but I think it depends on the lone pairs within a molecule. Like water is a monodentate because it can only bond through oxygen which has 2 sets of lone pairs. With en (ethylenediamine) since it has multiple nitrogens with lone pairs, it is able to bond through multiple site,...

Alan Cornejo 1a

Angela Prince 3B wrote:
Elizabeth Harty 3A wrote:How do you know if there are sigma bonds available for rotation?

all sigma bonds can rotate, but pi bonds cannot

Thank you for the clarification .

Alan Cornejo 1a

I know that atoms in group 3 can break the octet rule, but I have also seen similarly that even atoms like Cl can break the octet rule, Is there any other atoms outside of group 3, that can also break the octet rule, and if so is there a certain way to identify why exactly they are able to break the...

Alan Cornejo 1a

Jamie Lee 1D wrote:Technically they are the same thing so I don't think it matters, you would most likely get a problem correct with either name. Lavelle used bent in his lecture though.

Both terms usually refer to the same thing, correct.

Alan Cornejo 1a

Carbon Monoxide has a total of 10 valence electrons. Carbon having four and Oxygen having six they combine to have 10 total valence electrons. If the carbon and oxygen were double bonded (4 shared electrons), and each had a single pair then you would only have a total of 8 valence electrons. 1 lone ...

Alan Cornejo 1a

Elements in the 3p or higher orbital are exceptions to the octet rule. This is because they have an empty d-orbital that allows them to hold more than 8 valence e-, e.g. for P, it is located in the 3p orbital, but has an empty 3d orbital that allows it to hold more than 8 e- and be an exception. Th...

Alan Cornejo 1a

zachary_nhem_4I wrote:Sigma bonds are stronger because the two orbitals overlap, as opposed to a pi bond where the two orbitals are side by side.

This response is correct as the overlapping of two P orbitals causes the stronger force.

Alan Cornejo 1a

Yes any single bond has one sigma bond, a double bond has one sigma and two pi bonds, and a triple bond has 1 pi and two sigma bonds

Alan Cornejo 1a

Yes all single bonds are sigma bonds, and double bonds contain one sigma and one pi bond, and a triple bond contains 2 pi bonds and one sigma.

Alan Cornejo 1a

Thanks for the help !

Alan Cornejo 1a

I think that a good night's sleep is pretty important too. I'd suggest to not stay up super late cramming because that can limit your ability to perform on the test due to lack of sleep. Yeah I've read about how sleep can inhibit cognitive abilities by over 60% over just one bad nights sleep. Thanks

Alan Cornejo 1a

Sunday is the deadline and we must have 50 posts

Alan Cornejo 1a

If you search for "marshmallow" you will find past exam problems for review

Alan Cornejo 1a

On the syllabus it says a 50% is needed to pass with a C- or higher and so I assume thats a curve in and of itself

Alan Cornejo 1a

I really feel like going to the review sessions helps alot as it helped me greatly and they are very useful

Alan Cornejo 1a

ramiro_romero wrote:Just make sure you eat an apple, glucose molecules will store in your body and fuel your brain ability!

Thats a great idea, thanks for the advice.

Alan Cornejo 1a

Any thoughts/advice as to the best nutritious and energizing breakfasts for sunday morning before the final ?

Alan Cornejo 1a

A conversation between two atoms:
I think I’ve lost an electron.
Are you sure?
Yeah, I’m positive.

Alan Cornejo 1a

My teacher threw Sodium Chloride at me. That’s a salt.

Alan Cornejo 1a

“What do you do with a sick chemist?”
“If you can’t helium, and you can’t curium, then you might as well barium.”

Alan Cornejo 1a

helium walks into a bar and orders a beer. The bartender says, “Sorry, we don’t serve noble gases here.” He doesn’t react

Alan Cornejo 1a

Alexis 3F wrote:I've been attending the workshops a few times a week and it's made suchhhh a positive improvement!!!!

I also found this to be super helpful

Alan Cornejo 1a

905416023 wrote:It is 1 angstrom to 10^-10 m

correct answer

Alan Cornejo 1a

nicolely3B wrote:Hz is the unit for 1 cycle/second. The cycle refers to a wave's cycle and it's from the peak of one wave to the trough of the next

perfect explanation

Alan Cornejo 1a

reading the textbook is an obvious super helpful tool, to better go in depth as to what you are learning and practice.

Alan Cornejo 1a

Typically, ionic bonds are stronger but there are exceptions such as weakened ionic bonds as water as well as special strengthened covalent bonds known as covalent network bonding.

Alan Cornejo 1a

I used these for my AP Chemistry class in high school, but I think they have some college-level chem as well: https://chem.libretexts.org/ https://www.youtube.com/channel/UCEWpbFLzoYGPfuWUMFPSaoA https://www.youtube.com/watch?v=IFKnq9QM6_A&list=PLJfwA7_CzYE_qLSXH2hJkpffcrc76NjHJ Hope this helps...

Alan Cornejo 1a

madeleine_dis1E wrote:Yes, the 700-400nm example he gave is meant to provide a mental picture of the range however the actual scale is from 720-400. Either way you want to remember it is ok.

correct, 700 is just used for an easier conceptualization of the actual range

Alan Cornejo 1a

great tool and resource to help review and further cement the fundamentals of each topic covered in class !

Alan Cornejo 1a

You have the option of either doing more problems from week 1 of Chem review or the quantam world

Alan Cornejo 1a

I don't know if someone has asked this already but would we get partial credit for unfinished problems headed in the right direction? I was also wondering this as, I was also curious as to how far off of an answer would grant us the maximum amount of points ie. our answer is 8.4 whereas the actual ...

Alan Cornejo 1a

You only need to use the molar mass of one reactant to find the product, so you can keep the molar masses of the products separated. First, convert the grams given of a particular reactant to moles. Then, use the molar ratio of the balanced equation to determine how much of a particular product is ...

Alan Cornejo 1a

Actual yields will be less than theoretical yields due to side reactions that can occur, some products could stick to the sides of the reaction container, and impurities that are bound to happen during almost all chemical reactions. Hope this was helpful/answered your question! exactly ! There are ...

Alan Cornejo 1a

Great and awesome to hear that you still think about and take time to give advice to students of a teacher you had so long ago. We all appreciate the advice and good luck to you and all your endeavours .

Alan Cornejo 1a

I think the best way to relax and get rid of the nerves is to just close your eyes and breathe, just focus on good and positive memories and experiences will enhance your mood making you happier, the happier you are the more willing you are to focus and do something, it will also help clear your min...

Alan Cornejo 1a

Typically the amount of significant figures used for your answer is determined by the amount gaven to you in the question. Usually it follows these rules
any non-zero digits are always significant.
Any zeros between two significant digits are still significant.

Search found 98 matches