CHEMISTRY COMMUNITY

Diana Aguilar 3H

Hi! Yes, the denominator of the reactant quotient would just be 1!

Diana Aguilar 3H

Hi! Like many have stated before, a bomb calorimeter is considered a "perfect system" since it is an isolated system which means no energy/matter can leave the system or be brought in.

Diana Aguilar 3H

Hi! I believe you can use bar or atm since they are very similar when calculating Kp

Diana Aguilar 3H

I believe that we should always have temperature in units of Kelvin since using Celsius might give you issues with your answer and units, so unless the question directly asks for the units to be in celsius, just stick to using Kelvin.

Diana Aguilar 3H

Hi! I believe you still have to take into consideration the coefficients for the exponents when writing the constant equation.

Diana Aguilar 3H

Hi! Like many others have stated, E(max) is the maximum voltage difference in a system :)

Diana Aguilar 3H

Hi! Only a change in temperature can change K!

Diana Aguilar 3H

Hi! Like many others have stated, the overall order of a reaction can be found by adding the individual orders of the reactants together.

Diana Aguilar 3H

Hi! Like many have stated, n represents the number of electrons being transferred which can be found in the balanced half reactions of the redox reaction.

Diana Aguilar 3H

Hi! Like many others have stated, you use the nernst equation when you are calculating the cell potential under non-standard conditions/when the reaction is not at equilibrium.

Diana Aguilar 3H

Hi! Like many others have stated, q represents just heat while qrev represents the heat of a reversible reaction.

Diana Aguilar 3H

When trying to choose what R value to use, you should try looking at/keeping track of the units given to you in the problem to ensure that the units all match so that in your final answer, you end up with the desirable units.

Diana Aguilar 3H

Hi! A forward reaction is from reactants to products (A->B) so it moves from left to right and a reverse reaction is from products to reactants (B->A) so it moves from right to left.

Diana Aguilar 3H

Hi! Like many others have stated, usually the naught symbol means the reaction occurs under standard conditions which would be like 298K and so forth.

Diana Aguilar 3H

Hi! Like many have stated, delta H naught represents change in enthalpy under standard conditions and delta H just represents change in enthalpy.

Diana Aguilar 3H

Like many others have stated, Delta U is equal to 0 for isothermal expansions because the temperature stays constant.

Diana Aguilar 3H

I think it has to do with log rules, logab = log a + log b, and also because pKa and pKb are log functions.

Diana Aguilar 3H

Like many have stated, delta G naught is at standard conditions, while delta G is not

Diana Aguilar 3H

This was super helpful, thank you so much for the summary!

Diana Aguilar 3H

Hi! Like many others have stated, a perfect isolated system is theoretical since there has to be some exchange of energy.

Diana Aguilar 3H

Like many others have stated, heat is not a state function because it depends on the pathway of the reaction, while enthalpy does not rely on the pathway, only the initial and final states of the reaction matter.

Diana Aguilar 3H

Hi! I think it is best to convert your units from mmol/L to mol/L since the units for Q are mol/L, unless the questions tells you otherwise.

Diana Aguilar 3H

A catalyst only lowers the activation energy of a reaction, so it should have no affect on equilibrium or anything else.

Diana Aguilar 3H

Like many others have stated, Q is equal to K at equilibrium, while Q is mainly used when the solution is not at equilibirum.

Diana Aguilar 3H

The way you know if one of the reactants is part of the slow step is if they are part of the overall rate law, but usually the question will tell you.

Diana Aguilar 3H

Hi! Yes, those are all state functions and there are others as well like temperature.

Diana Aguilar 3H

Hi! Molar heat capacity is measuring the number of moles, while specific heat capacity is measuring the mass in grams

Diana Aguilar 3H

Hi! Enthalpy focuses on the change of heat in a system, while entropy focuses on the change in disorder of a system

Diana Aguilar 3H

Heat is the transfer of energy between two systems because of an energy difference while enthalpy measures the change of amount of heat in a system

Diana Aguilar 3H

It is important to know what units are given to you in the question to see what value you have to use, but as long as your units cancel out and you have the correct units at the end then you should be fine.

Diana Aguilar 3H

A pH meter measures the concentration of H+ ions in a solution to determine its acidity.

Diana Aguilar 3H

I believe its because since larger molecules have more atoms, this will lead them to having a greater disorder/ways that the atoms can be arranged, which means larger molecules will inturn have higher entropy.

Diana Aguilar 3H

Like many others have said, you should try to keep track of/look at the units you are given in the equation to help you determine what gas constant to use!

Diana Aguilar 3H

Hi! I believe the only factor that can affect the equilibrium constant is temperature.

Diana Aguilar 3H

I believe k is just Boltzmann constant which is 1.38x10^—23 J/K

Diana Aguilar 3H

Thank you everyone for the explantions, they were really helpful since this was a concept I was also confused about!

Diana Aguilar 3H

I believe K and Kc are the same concept, the only difference is that Kc is specifically for the equilibrium constant of concentrations and Kp is for partial pressures.

Diana Aguilar 3H

I believe coefficients do not affect the oxidation number, they are just there to help balance the equation.

Diana Aguilar 3H

Yes, like many others have stated, only gases apply to Le Chatelier's Priniciple

Diana Aguilar 3H

Yes, I believe you would assume it's at standard conditions, 25 C or 298 K :)

Diana Aguilar 3H

You would most likely have to look at the units given and then from there determine which R value/constant is best to use.

Diana Aguilar 3H

G°is under standard conditions (298 K and 1 atm) and G is not.

Diana Aguilar 3H

State property only focuses on the final value and the initial value, and does not focus on the path taken to reach the state.

Diana Aguilar 3H

Thank you everyone for the explanations and examples, this really helped since this was also something I was having some trouble with!

Diana Aguilar 3H

Since K is a ratio, when you solve for K all the units cancel out so in the end K is left unitless.

Diana Aguilar 3H

Thank you everyone for the explanations and tips, I also was having trouble with problems involving Hess's Law and this was really helpful!

Diana Aguilar 3H

I believe it really depends on what units the question is asking for. One thing you do have to remember is to make sure that all your units are either in Kelvin in the equation or they are all in Celsius.If they are not you have to convert them so all the units in the equation are the same.

Diana Aguilar 3H

Like many have said, the negative sign would go on the side that is exothermic, which means it is losing heat.

Diana Aguilar 3H

Yes, like others have stated, you would just have to draw out the lewis structure.

Diana Aguilar 3H

Hi! I believe we can assume x is insignificant when the k value is less than 10^-4

Diana Aguilar 3H

Like many have stated before, there is no difference between vapor and gas, they mean the same thing :)

Diana Aguilar 3H

HClO3 would be considered a strong acid

Diana Aguilar 3H

Exothermic is when energy is being released, like in the forming of bonds, and endothermic is when energy is required, like when you are breaking bonds. This is how I think of it, hope it helps!

Diana Aguilar 3H

I was also having trouble with which strong acids/bases I should memorize, so thanks to everyone for the resources and explanations, it really helped!

Diana Aguilar 3H

When you reverse a reaction, you would take the reciprocal of K so it would be 1/k.

Diana Aguilar 3H

Phase change is when a substance goes/changes from one state of matter to another, an example would be when a solid changes to a liquid and so forth.

Diana Aguilar 3H

I was also wondering about this, thank you everyone for the explanations and resources, they were really helpful!

Diana Aguilar 3H

When there is one arrow present, that usually means that the reactions favors that side of the reaction.

Diana Aguilar 3H

When breaking a bond, energy is required. On the other hand, when a bond is formed, energy is released.

Diana Aguilar 3H

Yes, like others have said, endothermic reactions will always have a positive delta H and exothermic reactions will always have a negative delta H

Diana Aguilar 3H

Yes, like many have stated, partial pressure only applies to gases!

Diana Aguilar 3H

Like many have stated before, we will most likely be given a constant sheet to use for the exam, so I do not think you have to memorize it :)

Diana Aguilar 3H

Like others have said, I think it would be best to try and memorize the strong acids/bases.

Diana Aguilar 3H

I do not think we use them/go over them in this course!

Diana Aguilar 3H

Thank you everyone for the helpful tips and advice, it really helps!

Diana Aguilar 3H

Thank you to everyone for the explanations, I was also having trouble with this!

Diana Aguilar 3H

Thank you so much for the explanation, it really helped me figure out how to solve a similar problem I had!

Diana Aguilar 3H

Hi! The units for temperature should be in kelvin I believe.

Diana Aguilar 3H

I believe the concentrations of P and R should be given to you in the problem in some way.

Diana Aguilar 3H

Hi! I believe the unit should be atm, I do not think we have to convert to pascals.

Diana Aguilar 3H

Dipole arrows move/point towards the more electronegative atom.

Diana Aguilar 3H

Bent and angular refer to the same molecular geometry.

Diana Aguilar 3H

Pi bonds are only applicable to covalent bonds.

Diana Aguilar 3H

I thinks it's mostly going to be j/photon, but it can also be j/atom, it really depends on the question.

Diana Aguilar 3H

Water can be both an acid and a base since it is amphoteric.

Diana Aguilar 3H

The coordination number is the number of atoms the central atom is bonded to. I believe it is important to know because it allows us to find the name and shape of the coordination complex.

Diana Aguilar 3H

Thank you so much for sharing this with us, it is really helpful!

Diana Aguilar 3H

The most common geometry for a complex with a coordination number of 6 would just be octahedral.

Diana Aguilar 3H

Thanks everyone for the clarification, I was always having a hard time with finding the oxidation number!

Diana Aguilar 3H

Thank you to everyone for the clarification, I also was wondering what that meant as well!

Diana Aguilar 3H

One sigma bond is just a single bond and one can be found in all bonds. Pi bonds are found in double and triple bonds. There is 1 pi bond and 1 sigma bond in a double bond and 2 pi bonds and 1 sigma bond in a triple bond. Hope this helps!

Diana Aguilar 3H

I think when we are trying to find the shape of a molecule, you have to draw/use the most stable lewis structure, but I am not very sure. This is also something that I wanted to know as well.

Diana Aguilar 3H

Molecular geometry is not affected by bond type, it is affected by the amount of lone pairs there are.

Diana Aguilar 3H

The shape would be bent or angular, and you can use either term to describe the shape since they mean the same thing.

Diana Aguilar 3H

Equatorial atoms positioned horizontally on the same plane as the central atom and surround it you could say, while axial atoms are vertical which would be above and below the central atom.

Diana Aguilar 3H

I was also having some trouble with angle size, thanks to everyone for the explanations and the resources to figure this out, it was very helpful!

Diana Aguilar 3H

Yes, all single bonds contain a sigma bond and a double and triple bond also contain one sigma bond as well.

Diana Aguilar 3H

All single bonds contain a sigma bond, double bonds contain a sigma bond and a pi bond, and lastly a triple bond has one sigma bond and two pi bonds.

Diana Aguilar 3H

Thank you to everyone for the explanations, I was also having some trouble with this topic!

Diana Aguilar 3H

Ionization energy increases as you go up and across (to the right) the periodic table.

Diana Aguilar 3H

Thank you for sharing, this is really helpful!

Diana Aguilar 3H

Yes, you are correct. Electron affinity and ionization energy follow/have the same trend as electronegativity.

Diana Aguilar 3H

Thank you so much to everyone for the clarification, I was also having trouble with this topic!

Diana Aguilar 3H

Yes, london dispersion Forces are found in all molecules but they are the weakest bond.

Diana Aguilar 3H

By today, we should have 35 posts and 50 by the end of the quarter since we have to post five posts each week.

Diana Aguilar 3H

Hi everyone! Can someone help me out with this problem from the textbook?
"Arrange the cations, Rb^+, Be ^2+, and Sr^2+ in order of increasing polarizing power. Explain your reasoning."

Diana Aguilar 3H

I was also having trouble with determining electronegativity, thank you to everyone for the clarification, it really helped!

Diana Aguilar 3H

I'm having trouble with this problem in the textbook, can someone help me out?
"Draw the Lewis structure of (a) tetrahydridoborate ion, (b) hypobromite ion, (c) amide ion,"

Diana Aguilar 3H

I think we do have to draw the lewis structure with the lowest fromal charge since it is the most stable, but I don't think we will have to draw them on the midterm since it is multiple choice.

Diana Aguilar 3H

I was also having a hard time with the classification of Lewis Acids and Bases, so I'm glad you asked. Thank you so much to everyone for the clarification, it was very helpful!

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