CHEMISTRY COMMUNITY

Sara Flynn 2C

The pseudo first order can be used when there are multiple reactants in a reaction

Sara Flynn 2C

When mixing the reactants, just put one in large excess so that when it reacts the amount that reacts would not have an impact on the concentration and so the order of a certain reactant can be determined. For example, if one reactant had a concentration of 1.9 x 10 ^-5 M and another had a concentra...

Sara Flynn 2C

I think it just means that if you have more reactant initially then compared to how much product would be formed if you had less reactant there would be more. Like if you had 2 moles of reactant and it made 3 moles of product, if you had 4 moles of reactant then it would make 6 moles of product.

Sara Flynn 2C

A first order reaction means that when the reactant increases the product increases by the same factor and a second order means that, depending on the way in which it is a second order reaction, an increase in the reactant means an increase in the rate by the factor squared or an increase in the two...

Sara Flynn 2C

When calculating the instantaneous rates you are finding it for a specific species and the unique rate takes into account the stoichiometric coefficient of the equation and so it makes all the unique rates for each species that same

Sara Flynn 2C

The rate determining step is just the slowest step of the reaction and is the only one (or ones if there are multiple) that will effect the rate of the reaction and so performing an experiment where you change the concentrations of different reactants and see the impact on the rate can help you dete...

Sara Flynn 2C

The difference between E and E knot is that E knot is when the cell is under standard conditions and E is for the cell under any conditions

Sara Flynn 2C

You take the parts of the chemical reaction that are involved in the oxidation reaction and the parts that are involved in the reduction reaction and make two half reactions and the point is to make sure that there is an equivalent number of electrons on each side that will cancel

Sara Flynn 2C

It helps you find the cell potential when the cell is not under standard conditions, like when the cell is not at 1M

Sara Flynn 2C

since the temperature is in kelvin and there is no such thing as negative kelvin whether or not the second value is positive or negative is dependent upon the entropy of the system

Sara Flynn 2C

If it is anything like the way grading was done last quarter then it should be after lecture on Wednesday, but it may be different because of the holiday weekend.

Sara Flynn 2C

Yes, the equation is just demonstrating the concept that we previously learned that K changes depending on the temperature at which the reaction is taking place

Sara Flynn 2C

free expansion means that it is expanding into a vacuum and so there is no work being done because it does not have to push against any pressure from the outside.

Sara Flynn 2C

if an ideal gas is expanding isothermally that means that it is happening at a constant temperature and this can happen because as the system is expanding and the volume is increasing and the work is being done, the temperature is being kept constant by heat that is flowing into the system to mainta...

Sara Flynn 2C

an intensive property is something that is true no matter how much mass there is of a substance while an extensive property depends on how much product is present

Sara Flynn 2C

Free Expansion means that there is unrestrained expansion, like in an open system where the gas will continue to expand because there is nothing that is stopping it from doing so

Sara Flynn 2C

If the system does work then the work is positive, if work is done on the system then the work is negative

Sara Flynn 2C

It should not matter because KJ is just 1000 J, as long as you are using the proper units so that everything will cancel properly you should be good.

Sara Flynn 2C

It might be referring to that time in lecture when he talked about the ATP concentration in healthy muscle tissue and dead muscle tissue and we were supposed to find the expected equilibrium concentrations for ADP and Pi in the dead tissue

Sara Flynn 2C

equilibrium concentration

Sara Flynn 2C

An inert gas will not affect the equilibrium because it is not a part of the reaction and will not change the pressures of the gases in the reaction

Sara Flynn 2C

The compound will dissolve in the solution and the Al will combine with water to form Al(H2O)6 ^+3 and its conjugate base would be Al(H2O)5OH^+2

Sara Flynn 2C

it is the concentration of the conjugate acid over the concentration of the initial base multiplied by 100

Sara Flynn 2C

Yes, these ions are spectator ions and will not change the pH because they are stable as ions and do not donate or pull protons to or from the solution

Sara Flynn 2C

As long as a molecule has a proton to donate and lone pairs to accept a donated proton then it should be able to go through an autoprotolysis reaction

Sara Flynn 2C

No, the values are different because there are two different units or properties of the gases being measured in each case and so they will give different values. There is a formula to convert between the two though

Sara Flynn 2C

The only time when neither direction is favored is when K is equal to one, any other time one direction is favored it is just not considered to be strongly favored unless K>10^3 or K<10^-3

Sara Flynn 2C

I think that when just K is listed it usually is referring to Kp because the pressures give a more accurate value than the concentrations

Sara Flynn 2C

Le Chatelier's Principle states that when a system is stressed it will try to correct that stress, basically when you change the concentrations or the partial pressures of the system you are changing the value of Q, but the value of K remains constant and so the system will either proceed towards th...

Sara Flynn 2C

Catalysts increase the speed of a reaction by lowering the activation energy of the reaction, they would have no effect on the equilibrium constant or stress the system they would just make the system approach equilibrium at a quicker speed

Sara Flynn 2C

pi bonds can't rotate because they are overlapping side to side and not head to head like a sigma bond.

Sara Flynn 2C

A Bronsted base is just a proton acceptor and a bronsted acid is a proton donor. A Lewis base is an electron pair acceptor and a Lewis base is an electron pair donor. In almost all cases the molecule that is the bronsted base will also contain the molecule that is a lewis base and same for acids. Ex...

Sara Flynn 2C

for example the ligand NH2CH2CH2NHCH2CH2NH2 is called diethylenetriamine and if there were two of them located in a cordination compound then it would be bisdiethylenetiramine in the naming

Sara Flynn 2C

A sigma bond is always the first bond that two atoms will make and they are overlapping head to head. All of the following bonds that will be made between the same two atoms are pi bonds that overlap side to side.

Sara Flynn 2C

Period 3 elements can be an exception to the octet rule because they are able to use their d orbital for bonding. H, He, Li, Be, and B are also exceptions because they are more likely to lose their electrons than to accept more.

Sara Flynn 2C

If the question asks for the shape of electron arrangement, then you would consider all electron densities including the lone pairs. If he question asks for the molecular shape, then you would only consider the bonded atoms.

Sara Flynn 2C

The electron arrangement around the atom is a tetrahedral, but the molecule shape is a trigonal pyramidal. The lone pair takes up more space than a bonded pair of electrons because it is attached to only one atom instead of two. The lone pair forces the other atoms closer to each other which is why ...

Sara Flynn 2C

A pi bond influences rotation because it makes it so the molecule is unable to rotate since there is electron density on both sides of the internuclear axis. If the molecule would try to rotate around the bond it would break the bond.

Sara Flynn 2C

A sigma bond is an end to end overlap and so once a sigma bond is formed the molecule is unable to make a second sigma bond because there is no way to orient the molecule that would allow for another end to end overlap. Therefore the second and third bond that are made in a triple bond have to be si...

Sara Flynn 2C

Hydrogen bonds only occur if the hydrogen atom is bound to N, O, or F and the partial positive charge created on the hydrogen atom is attracted to the partial negative charge on the N, O, or F atom.

Sara Flynn 2C

They are held tighter when they are in a bond because they are between two atoms, when they are lone pairs they are only attached to one atom and can spread out more

Sara Flynn 2C

A dipole is a molecule with a partially negative charge on one part of the molecule and a partially positive charge on another part of the molecule. This is always present in polar molecules, but in nonpolar molecules an induced dipole can be created. An induced dipole occurs when the electron densi...

Sara Flynn 2C

yes, both decrease down a group and increase moving to the right in a period.

Sara Flynn 2C

I believe that the correct answer would be B A is wrong because the difference between energy levels as the energy levels increases is smaller, so for this problem going from n=5 to n=3 the electron would go from n=5 to n=4 and from n=4 to n=3 and for going from n=4 to n=2 the electron would go from...

Sara Flynn 2C

Oxygen is more electronegative than chlorine (oxygen is 3.5 and chlorine is 3.0) so oxygen would be the central atom and is bonded once to each chlorine atom (Cl-O-Cl)

Sara Flynn 2C

it will be in the range of +- delta x/2 because the uncertainty in x is the range of possible answers (if delta x is four then the range of answers is +-2)

Sara Flynn 2C

yes, the electrons would be removed from the highest energy level first, which is the 4s when it has electrons

Sara Flynn 2C

The pull from the nucleus increases for each individual electron because it has less electrons to pull when it has a charge of plus one and so the electrons that remain are more difficult to remove and require more energy to remove than the first electron

Sara Flynn 2C

The kinetic energy is the energy that is transferred to the electron after it is ejected, which is the energy that is left over from the photon after it has overcome the work function which is the energy required to remove the electron from a specific metal

Sara Flynn 2C

Yes, the energy of the photon just has to be equal to or greater than the work function of that specific metal to eject an electron.

Sara Flynn 2C

A nodal plane is an area of the orbital where there is zero electron density. The p, d, and f orbitals have nodal planes while the s orbital does not. This is why the s orbital is a sphere while the p orbital has two lobes on either side of the nucleus with a nodal plane in between them.

Sara Flynn 2C

So electrons in higher energy states contain higher potential energy, while electrons in lower energy states contain lower potential energy? Does this mean that electrons in higher energy states are more unstable than electrons in lower energy states? Yes, they are more unstable because the higher ...

Sara Flynn 2C

light cannot exist in a stationary state and so there is no mass because it is not a possible situation

Sara Flynn 2C

If the threshold energy is not met then the incoming photon passes through the surface because it is unable to interact with the electrons of that metal since they are only able to absorb energy in discrete amounts

Sara Flynn 2C

as long as the answer is correct the units are not important

Sara Flynn 2C

Do all our final answers need to be converted to the base SI unit (ex:meter, kilogram, mole) or do we just use the closest prefix to it? And if we leave our answer in the base SI unit and do not use a prefix simplifying the value would our answer be wrong even if both answers would be mathematicall...

Sara Flynn 2C

I do not think that the sig figs in the constant are important because the sig figs in your answer rely on the numbers that are given to you in the problem, but the more sig figs you use for the constant the more accurate your answer will be.

Sara Flynn 2C

Yes since molarity is mol/L if you did not convert the mL to L it would be the wrong units and your answer would not be giving molarity.

Sara Flynn 2C

The unit for molarity is mol/L and so when diluting a solution the moles in the solution are relevant for finding the concentration of the new solution.

Sara Flynn 2C

Do you have to find moles before finding limiting reactant? Yes. To find the limiting reactant you need to find which one of the reactants there is less of and since they react together in a specific mole ratio, you need to find out how many moles of each product you have before you can know which ...

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