CHEMISTRY COMMUNITY

shaunajava2e

the solution manual shows that the equation for rate of reaction is: - (deltaConcentration) / (deltaTime). Why is there a negative in the equation/formula?? This is the problem im referring to: 15.3 6th ed. In 20. s, the concentration of nitrogen dioxide, NO2, decreases from 450 mmol/L to 320 mmol/L...

shaunajava2e

for 11.83 we need the delta G value, the solution manual uses deltaG=deltaH - T* deltaS using values from appendix 2A, but can’t we just use the deltaG values from appendix 2A and use the deltaG= sum(deltaG products) - sum(deltaG reactants) ??? is there a reason they’re using the deltaH and deltaS t...

shaunajava2e

more specifically i’m referring to questions 11.15 and 11.21 6th ed, they’re the same reaction occurring at the same temp, but one asks for the standard gibbs (and gives the k value only) while the other asks for the reaction gibbs (giving both k and the partial pressures). so what i’m understand is...

shaunajava2e

thanks!

shaunajava2e

What’s the difference between standard gibbs free energy and reaction gibbs free energy?

shaunajava2e

review the hw problems!!

shaunajava2e

Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

test 2 is Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

are we assuming temperature is never below 0K?

shaunajava2e

do you mean test 2? Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

thank you so much!!

shaunajava2e

do you mean test 2? Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

In thermodynamics, the Gibbs free energy is a thermodynamic potential that can be used to calculate the maximum of reversible work that may be performed by a thermodynamic system at a constant temperature and pressure.

shaunajava2e

it covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation (which is all the new material covered in class Weeks 6 and 7)

shaunajava2e

Test 2 covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation (which is all the new material covered in class Weeks 6 and 7).

shaunajava2e

it covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation

shaunajava2e

Test 2 covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation (which is all the new material covered in class Weeks 6 and 7).

shaunajava2e

Test 2 covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation (which is all the new material covered in class Weeks 6 and 7).

shaunajava2e

talk to your TA, depending on the problem usually either they can help you with it

shaunajava2e

I'm a little confused, for number 9.67 in the 6th edition it says: Assume that deltaH and deltaS are independent of temp and use data from appendix 2a to calculate deltaG for each of the following reactions at 80C. Over what temperature range will each of the reactions be spontaneous under standard ...

shaunajava2e

The standard enthalpy of formation is defined as the change in enthalpy when one mole of a substance in the standard state (1 atm of pressure and 298.15 K) is formed from its pure elements under the same conditions.

shaunajava2e

All elements in their standard states (oxygen gas, solid carbon in the form of graphite, etc.) have a standard enthalpy of formation of zero, as there is no change involved in their formation.

shaunajava2e

An isolated system is a thermodynamic system that cannot exchange either energy or matter outside the boundaries of the system. An isolated system differs from a closed system by the transfer of energy. Closed systems are only closed to matter, energy can be exchanged across the system's boundaries.

shaunajava2e

Breaking Bonds Requires Energy. You have to put energy into a molecule to break its chemical bonds. The amount needed is called the bond energy.

shaunajava2e

a lot of the questions tend to jump around if you're following what we learn in class, but by the end of the chapter we usually have covered all the topics

shaunajava2e

they are both units of measurement for pressure and depending on your TA, both should be fine to use

shaunajava2e

A quick difference between endothermic and exothermic involves reactions in the environment. An endothermic reaction takes place when energy is absorbed from surroundings in the form of heat, and exothermic is when energy is released from the system into the surroundings.

shaunajava2e

week two can be either outline 1 or 2

shaunajava2e

the rates of product changing to reactants and reactants changing to products are the same

shaunajava2e

the formulas are the same, K is at equillibrium

shaunajava2e

You must be full of copper and tellurium because you're CuTe!

shaunajava2e

The best thing about learning equilibrium is that nothing changes.

shaunajava2e

Don't tell jokes to noble gases you'll get no reaction.

shaunajava2e

elements in the 3rd period and onwards are able to take advantage of their empty d orbital and expand their octet past the 8 electrons that come with the p and s orbitals.

shaunajava2e

all the good chemistry jokes Argon, i think we should take the bad ones and Barium.

shaunajava2e

shaunajava2e

what is the chemical formula for a banana?
BaNa2

shaunajava2e

the longer the bong the weaker it is, this is because if the bond length is longer it is easier to break

shaunajava2e

if you have accounted for all the electrons and checked for everything else (like stated above,) yes, formal charge is a great way double check that your structure is in the most stable form.

shaunajava2e

e=hv, like stated above should have been used, but it was also necessary to convert the units from kJ to J which could result in error as well.

shaunajava2e

^^ the rule applies for copper and chromium and all elements under them in the 9th and 6th groups (however lavelle said in class we won't be going past the 4th period so we don't need to worry about any elements other than copper and chromium)

shaunajava2e

since there was only the two bonds, the length would be the average of their individual lengths, so the average of 140 and 120, resulting in 130

shaunajava2e

formal charge is very relative and dependent on the amount of valance electrons an element has in the periodic table and how many it is given in the lewis structure

shaunajava2e

the location of a bond in a structure can be interchanged, there is a resonance structure.
in this example, the double bond can be written on either side and therefore there is resonance

shaunajava2e

formal charges can be used to help determine the most stable lewis structure, however you dont need to explicitly state them unless the questions says so

shaunajava2e

thats correct! and the shorter the bond the stronger it is

shaunajava2e

the goal is to make the formal charge for each element 0 or as close to 0 as possible. if after calculating the formal charges of each element in the compound there are no elements with 0 formal charges, there is likely a better structure that can be shown.

shaunajava2e

electrons in the 3rd period and on can take advantage of their empty d orbital and use it to hold electrons and make themselves more stable by reducing their formal charge (resulting in going over the 8 that gets held by the p+s orbitals)

shaunajava2e

ionic radius, atomic radius, and covalent radius all follow the same trends, increases down a group and decreases across a period, being greatest in the bottom right corner of the periodic table

shaunajava2e

all elements follow the octet rule except hydrogen, helium, lithium, and beryllium which have a max of 2 valance electrons

shaunajava2e

the number of electrons is equivalent to the amount of valance electrons the element has

shaunajava2e

reviewing whats on the quantum world outline on his website should help!

shaunajava2e

thank you these are so helpful!

shaunajava2e

everything uses kg, molar mass is given in g per mole however for simplicity purposes and to make it easier to write out.

shaunajava2e

the equation is used to calculate the range in momentum or position of the electron as both cannot be calculated accurately at the same time. due to the way we carry out the experiment to calculate for position and momentum, we can not be certain of the values of one.

shaunajava2e

1 J= 1 kg.m^2.s^(-2) the units in the de broglie equation are: (J.s)/(kg.m/s) this becomes: [(1 kg.m^2.s^(-2))(s)]/(kg.m/s) the kgs on both sides cancel out there is a s^(-2) and s on top, and a s on the bottom, these cancel out as well the m^2 on top cancels out with one m on the bottom to end with...

shaunajava2e

wavelengths under 10^-15 or 10^-18 are so small that their wavelengths cannot be detected and therefore are said to have no wavelike properties

shaunajava2e

everyday objects and objects that can be seen with the human eye won't have detectable wavelike properties

shaunajava2e

7 problems relevant to the material are due every week in your discussion section

shaunajava2e

adding an O atom would change the composition of the molecule and therefore change the substance

shaunajava2e

due to side reactions and impurities the actual yield will often be less than the theoretical yield

shaunajava2e

technically you can use any mass you choose however 100g is almost always used as it reduces the amount of calculations needed and makes it simpler

shaunajava2e

the empirical formula simplifies the ratio of the atoms in a formula, the molecular formula shows the actual number. as a result, the empirical formula of multiple molecules could be the same while the molecular formulas cannot

shaunajava2e

I'm assuming they are using the molar mass of H as its shown in the front cover of the book, in which case it would be 1.0079 g.mol-1 which has 5 sigfigs

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