CHEMISTRY COMMUNITY

Erin Kim 2G

The Nernst Equation E=E°-(RT)/(NF)lnQ can be used to find the concentration by solving in all the known values and then solving for Q. Then you can write down the formula for Q based on the reaction of the problem and plug in the known molarities to solve for the specific element's concentration you...

Erin Kim 2G

The more positive standard reduction potential is the stronger oxidizing agent- so is more likely to be reduced or gain electrons.
The more negative standard reduction potential is the stronger reducing agent- so it is more likely to be oxidized or lose electrons.

Erin Kim 2G

A catalyst is used up in the beginning and then later recreated.
An intermediate is not there initially but is later formed as a product which cancels out with the next step.

Erin Kim 2G

Oxidation is when the species loses electrons and reduction is when the species gains electrons. You would calculate the charge of the species based on its presence in the compound with known charges of elements. The oxidation would have electrons on the right side and the reduction would have elect...

Erin Kim 2G

Noble/ Inert gases do not affect the equilibrium or shifting of the equation at all. This is because the partial pressures of the gas do not change within the reaction.

Erin Kim 2G

If one side of the reaction (anode or cathode) does not have a solid component, than Pt (a solid) must be added in order to have a solute.

Erin Kim 2G

Thermodynamics determines the spontaneity of the reaction, but will not tell if the reaction will occur slowly or quickly. We use kinetics to determine the rate of the actual reaction, dependent on the rate law constant; if the activation energy is high then the constant will be smaller and vice ver...

Erin Kim 2G

For the first order
the half life equation is t(1/2)= ln2/k.
It is applicable to all first order rate reactions.

Erin Kim 2G

Yes if you plot [A] vs time and it is a straight line, it is the 0th order.
If you plot ln[A] vs time and it is a straight line, it is the 1st order.
If you plot 1/[A] vs time and it is a straight line, it is the 2nd order.

Erin Kim 2G

You don't have to take into consideration the reverse reaction, and by analyzing the initial reaction rates, you are also looking at the maximum possible rate of the reaction. It is also easier to calculate because the initial concentrations of the reaction are usually given.

Erin Kim 2G

A unique rate is a rate of appearance/disappearance of any of the species in a reaction divided by its stoichiometric coefficient. A unique rate will be the same for each reactant or product. When you calculate the average rate, the coefficient is not taken into the account, so the average rate can ...

Erin Kim 2G

k should not change even if the coefficients are changed.

Erin Kim 2G

Yes because you need a solid for electron current change.

Erin Kim 2G

The anode is on the left of the cell diagram, with solid electrodes on the outside and aqueous on the inside next to the salt bridge. The Cathode is on the right of the cell diagram, with solids on the outside and aqueous on the inside as well. You must add Platinum if they is no solid in the equati...

Erin Kim 2G

The first and second equations are the same; the second one simplified equals the first equation. These equations are used for situations in which the pressure is constant. However in irreversible functions in which the pressure is not constant, you would use the third equation. They all solve for w...

Erin Kim 2G

delta G= 0 is at equilibrium
delta G >0 is not spontaneous
delta G < 0 spontaneous

Erin Kim 2G

In oxidation, electrons are removed. This means that the charge becomes more positive. In reduction, electrons are added on. This means that the charge will become more negative. This scenario is oxidation because the element became more positive, thus lost electrons.

Erin Kim 2G

Entropy (S) is the measure of disorder. Enthalpy (H) is the measure of total heat content.

Erin Kim 2G

Anything about Gibbs Free Energy and the Start of Outline 5 are applicable for Week 7 Homework.

Erin Kim 2G

Use H+ for redox reactions.

Erin Kim 2G

Change in Entropy= nCln(T2/T1). When volume is constant the value C is Cv and is equal to 3/2R. This is also the case for monatomic gases.

Erin Kim 2G

You know the general equation for combustion is "molecule" + O2= CO2 + H20. So you would write out the combustion equations for all three of the molecules for which the heat of combustion is given. Then you would rearrange those equations to have the correct molecules cancel out to form th...

Erin Kim 2G

The term adiabatic means that there is no heat flow, or that q= 0. This means that the change in internal energy or (delta U) is going to be equal to w. In an isolated system there is no flow of matter or energy from the system to the surroundings.

Erin Kim 2G

This is because of the equation delta U= q+ w. If there is no change in internal energy, then consequently the opposite of w will equal q.

Erin Kim 2G

A state function does not depend on the path taken, only the start and end states of the system are taken into account. Delta U is only dependent on the final result so therefore is a state function. However q and w are both described by the path it took to calculate that value, and therefore are no...

Erin Kim 2G

I would use Hess' Law if the total deltaH is given of the reaction to add the two reactions, but if the total change in heat is not given I would use the Hf tables to find the specific heats of each of the reactants and products and add those to get the total deltaH.

Erin Kim 2G

A calorimeter is a tool used to measure the amount of heat used in a chemical reaction or process. It is used by measuring the temperature difference of the reaction.

Erin Kim 2G

Enthalpy is the study of heat absorbed or released in a chemical reaction. So when you calculate the change of heat in a system, you are calculating the enthalpy of the system. It can be represented by deltaH.

Erin Kim 2G

That is just the standard volume equation for a cylinder, and since volume is not constant for this piston we would use this equation to find out the change in volume for the pump. This is a standard math equation that should be known I believe, it is not on the constants and equations sheet.

Erin Kim 2G

The addition of inert gas does not affect which side the equation favors, and the equilibrium constant does not change as well.

Erin Kim 2G

When the pressure is increased, the volume is decreased, and the concentration is increased in a system, it will favor the side of the reaction with the less moles of gas. The vice versa is true as well. Because there are two moles of gas on both sides of the reaction, neither side will be favored.

Erin Kim 2G

You can ignore x in some instances because the amount that dissociates will be so little that it is insignificant to the overall decrease in the molarity. If the K value is extremely small, namely less than 10^-3, it means that reactants are favored in the reaction and so little of the reactants wil...

Erin Kim 2G

In an exothermic reaction one can almost consider heat as the product of the reaction. This means that as temperature increase the equilibrium would shift towards the left, because the temperature on the right, or number of "products" increased. Vice Versa, for an endothermic reaction, hea...

Erin Kim 2G

The strong acids include HCl, HNO3, H2SO4, HBr, HI, HClO4, and HClO3.
The strong bases include LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2.

Erin Kim 2G

A base with a hydrogen ion attached to it is a conjugate acid. An acid with a hydrogen ion taken away from it is a conjugate base.

Erin Kim 2G

Solids and liquids are not included in the equilibrium constant equation. They are put in as a value of 1 and only gases and aqueous elements are considered when solving for the equilibrium constant.

Erin Kim 2G

Q and K have the same formula, they are both the concentration of the products divided by the concentration of reactants.

Erin Kim 2G

neither is more important, it depends on the situation. You use kp for partial pressure, and kc for when the concentration is given.

Erin Kim 2G

square pyramidal. With less than 90 degree bond angles.

Erin Kim 2G

This is based on the electro negativity difference. The greater the electronegative difference, the more ionic the molecule is. Because oxygen is more electronegative than sulfur, co2 would have greater ionic character even though it is not an ionic molecule. Neither are.

Erin Kim 2G

no just know that the ph is -log(H+).

Erin Kim 2G

If they increase the H+ or H3O+ concentration in the solution, it is an acid. If they increase the OH- concentration in the solution, it is a base.

Erin Kim 2G

Monodentate means that there is only one binding site from the central transition metal to the connecting ligand. Polydentate means there are more than one binding site.

Erin Kim 2G

yes you can determine the molecular shape of the molecule, knowing the AXE formula because the number of electron densities are known. By counting the number of lone pairs and the number of atoms around the central atom you can know the shape and bond angles.

Erin Kim 2G

The resonance structure does not matter. You can classify an acid by if it accepts electrons, but if it donates electrons then the molecule is a base.

Erin Kim 2G

You check for the net dipole moment of the molecule. If the dipole moments cancel out because if the symmetric structure of the molecule, then it is non polar. If there is a net dipole moment, the molecule is polar.

Erin Kim 2G

it is solely dependent on the number of electron densities so we would consider all bonds (single, double, triple) and lone pairs as 1 region of electron density. therefore the hybridization would be sp3.

Erin Kim 2G

the electron geometry would be trigonal planar, because we are not considering lone pairs, only the atoms. However if we want to know the shape, we would take into consideration the lone pairs of the structure, 1, so the shape would be bent.

Erin Kim 2G

this is dependent on whether lone pairs are present on this structure or not. For the steric number of 4, with no lone pairs the shape is tetrahedral, with one lone pair it is trigonal pyramidal, and with two lone pair it is bent. For the steric number of 5, with no lone pairs the shape is trigonal ...

Erin Kim 2G

hybridization occurs, because when we observe the lewis dot structure of an element we see that they have more electrons attached than the traditional orbitals allot. To accommodate the excess electrons, hybrid orbitals are created which are in between the energy levels of the orbitals they are hybr...

Erin Kim 2G

A ligand can be classified as a Lewis base or something that is a electron pair donor. They bind to a central metal atom to form a complex.

Erin Kim 2G

a larger atom has weaker bonds because the valence electrons are at a further distance from the nucleus and therefore decreases the electronegativity of the atom because there is a weaker pull. You can refer to an atom's size with all three of these terms.

Erin Kim 2G

Dipoles are created by a charge difference between molecules, with a separation of positive charge and a negative charge within a distance. The dipole arrow points towards the more electronegative atom in the molecule.

Erin Kim 2G

Sigma Bonding are bonds from end to end. They always occur before pi bonds, and only exist as one bond. Pi bonds are sideways bonds that are overlapping and are weaker than sigma bonds. After the initial sigma bond in double or triple bonds, pi bonds exist.

Erin Kim 2G

Hydrogen Bonding is between H and N,O, F and is strongest of intermolecular forces.

Erin Kim 2G

yes it can still have resonance. The formal charge is used to find the most stable Lewis electron dot structure, ones with elements of formal charge closest to 0.

Erin Kim 2G

generally the equation is CxHyOz + O2= CO2 + H20

Erin Kim 2G

1) count number of valence electrons 2) put element with lowest ionization energy in middle 3) draw single bonds plus lone electrons to complete octet around all elements 4) check total electron number to match number of electrons, adjust accordingly 5) check formal charges around all elements to ge...

Erin Kim 2G

I believe they provide the scantrons for us at the midterm.

Erin Kim 2G

For chemistry 14a, we are only using the exception to the octet rule to accommodate for the d block. So any element in the 3rd period or beyond can have an expanded octet. I don't believe we have to expand this rule for the f block yet in this class.

Erin Kim 2G

The element with the lowest ionization energy is in the middle of the structure when drawing Lewis dot structure. Ionization energy increases across the period and decreases down the group.

Erin Kim 2G

A shortcut you can use for formal charge is to take the total number of valence electrons and subtract the lines and dots surrounding the atom. so FC= VE -(# of lines/bonds + # of dots).

Erin Kim 2G

ml= -1 would be px
ml= 0 would be py
ml= 1 would be pz

Erin Kim 2G

The electron configuration for H is 1s1 and for He is 1s2. If the element is stated as being an anion or cation then you would accordingly add or remove electrons.

Erin Kim 2G

I do not have that, but I would assume your TA has not updated the grades in the grade book yet. I have a 7/70 but have turned in homework all 3 weeks too. Don't worry about it because grades are not finalized yet.

Erin Kim 2G

The answer is C, because you can not know both the momentum and position of an electron in an orbital simultaneously and if one is known the precision in which you can know the other decreases.

Erin Kim 2G

electrons have a measurable wavelength and can be found by using De Broglie's equation (wavelength)= h/p.

Erin Kim 2G

schrodinger's equation represents a wave function and consists of quantum numbers to label orbitals and describe wave function. Those quantum numbers are n, which is the principal quantum number and represents the energy level, l, which represents the shape of the orbital, and ml, which represents t...

Erin Kim 2G

intensity directly relates to the number of photons in the light. So if the number of photons increases, then the intensity increases/ gets brighter even if the type (wavelength or frequency) of photon did not change.

Erin Kim 2G

If the peaks and troughs of a wave match up then they are constructive and when the two waves match up then their amplitudes will increase because they both help to build each other. However when the peak and trough of two waves hit then they become destructive and the wave amplitude will decrease. ...

Erin Kim 2G

They thought that the Kinetic Energy of electrons released would be proportional to the INTENSITY of the light. However they found that was not the case, and actually the frequency correlated to the release of electrons.

Erin Kim 2G

I would use Khan Academy and Crash Course/ look up other videos on YouTube in order to solidify my understanding in the topic.

Erin Kim 2G

Last time I took chemistry was junior year as well, and it was honors chemistry, not AP. It is hard to try and refresh all the skills but the online modules have been very helpful to jog your memory on basic chemistry skills. I would also recommend going to the step by step hours or the workshops th...

Erin Kim 2G

You do not need to know the molar mass of each element as every element has their mass listed under the symbol on the periodic table. Every test and quiz we will be given a periodic table.

Erin Kim 2G

All the elements in the acronym HOFBrINCl, (hydrogen, oxygen, fluorine, Bromine, Iodine, and chlorine) are included in the diatomic elements. Any time these elements are listed in a chemical equation they must have the subscript of 2 as you always assume they are diatomic.

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