CHEMISTRY COMMUNITY

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Catalyst will increase the rate of forwarding reaction by lowering activation energy.

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Intermediates are formed and then used in the reaction process. Catalysts are present at the beginning of a reaction.

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catalysis decreases activation energy of a reaction

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both should be okay

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Frequency factor represents the collisions of molecules in the correct orientation

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Arrhenius equation can be used to determine A if not given.

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When given the mechanism, the slow step is the one that is the same as the overall reaction as the overall rate of reaction is determined by the slowest step.

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An intermediate species is one that is present in the mechanism but not in the reactants nor the products of the overall reaction.

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Termolecular molarity is very rare.

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We calculate the initial rate (when there are no products present).

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When E is positive, delta G is negative and therefore spontaneous.

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Concentration cells are cells in which the anode and cathode are the same element but in different concentrations.

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Yes, electrolysis is utilized to drive non-spontaneous reactions.

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Also be sure to keep units consistent throughout.

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Those controlled by kinetics are usually short and ones controlled by thermodynamics are usually longer.

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It is the electric charge of one mole of electrons.

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As you said positive E refers to a spontaneous reaction, therefore negative E refers to a spontaneous reverse reaction or a nonspontaneous forward reaction.

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The salt bridge is used to prevent charge imbalance.

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In a system, the anode is where oxidation occurs and the cathode is where reduction occurs.

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Reducing agents provide an electron in order for a reduction reaction to occur, therefore losing an electron.
Oxidizing agents take on an electron in order for an oxidation reaction to occur, therefore gaining an electron.

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If delta G is negative, the reaction is considered spontaneous (favorable).

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Neither reaction is favored at equilibrium.

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Change in temperature.

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I believe you assume standard conditions.

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Delta s does not change, both s values may change but the difference between final and intitial remains constant.

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Lavelle briefly mentioned determining spontaneity at the beginning of thermo but I believe he'll be explaining this concept sometime this week.

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A molecule at 0 K will have 0 residual entropy, but only if it is perfectly ordered will the molecule have 0 entropy, if it is not perfectly ordered then some entropy will still be present.

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Yes, it is the same sheet.

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The monoatomic values are on the constants and equations sheet.

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They are separate concepts I believe.

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Constant volume and pressure indicates that they do not change during the reaction.

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Yes, constant external pressure.

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A closed system can exchange heat but not matter

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Kinetics is more interested in rate, whereas thermodynamics considers more only final and initial.

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Enthalpy is the total heat of a system.

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Just the first I believe.

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Delta H is the enthalpy of products minus the enthalpy of reactants.

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State function means it is independent of path taken. Work is an example of NOT a state function, it is dependent on path taken.

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The diagram Lavelle showed in class was the temperature curve of water.

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Add the enthalpy of the phase change.

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Yes, but K remains constant.

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Autoprotolysis is proton transfer between the same type of molecule.

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Yes, a shift to the left favors the reverse reaction so more reactants will be made. A shift to the right favors the forward reaction so more products will be made.

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Mainly ensure consistency with units.

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Most simply, K= Products/Reactants

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Q is calculated in the same manner as K, so no.

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K is dependent on concentration.

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Q can give us an indication of the reaction in that it can identify whether the forward or reverse reaction is favored in order to reach equilibrium at a given moment.

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Q would be larger but ultimately the reaction would reach equilibrium and K remains the same.

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Q is calculated in the same manner as K and used as a comparison to identify if given concentrations of a reaction are at equilibrium.

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Transplatin may also be useful to know.

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The negative charge created after the first dissociation makes it more difficult for the second dissociation to occur.

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I believe sig figs are also counted after the decimal when provided a pH and you are asked to give some numerical number, say a concentration for example. It was briefly mentioned by my TA.

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Typically, there will be more than one hydrogen.

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I think the main takeaway is that dirty coal has sulfur in it.

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It is most useful to know the patterns of the periodic table.

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Stronger acids are characterized by their ability to lose hydrogen ions more easily. It is in this way that strong acids can reach 100% ionization when dissociating in water.

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Both should be okay.

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Strong acids/bases are assumed, when approximating, to reach 100% ionization. Therefore, the denominator of the equilibrium constant equation is essentially zero which is why we do not use the equilibrium constant for strong acids/bases.

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There simply exist two common ways of defining an acid (or a base). Both the Bronsted definition and Lewis definition refer to the same thing yet identify it in different ways.

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Sigma bonds are stronger due to greater overlap end-to-end but also be sure to remember sigma bonds allow for rotation whereas pi bonds are rigid.

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If the ligand already has a name with di-, tri-, tetra-, or polydentate.

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Should be fine as long as you let your TA know.

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The coordination number is determined by the bonds to the central atom.

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Hybridization is the mixture of valence atomic orbitals during bond formation to explain the observed structure.

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Technically, the shape does not matter in a lewis structure, although Lavelle said drawing them symmetrically (or now similar to VSEPR model) would help to visualize the molecule.

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I believe that we will have to know slightly less/more and be able to make comparisons between two bond angles (ex. which is less?).

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Nick Lewis 3D wrote:Have we gone over sigma and pi bonds yet? Do we have any more information about what exact material will be tested?

Lavelle said he would discuss sigma and pi bonds on Monday.

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Dipoles cancel in the same way which vectors cancel. A vector can be broken down into a component in each direction. When summed, vectors that equal 0 are dipoles that cancel.

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Rod-shaped molecules allow for instantaneous dipoles to be closer and thereby stronger because rod-shaped molecules can align with more surface area close to other nearby rod-shaped molecules.

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As intermolecular forces increase, the structure becomes more stable and therefore the melting/boiling points will also increase.

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As atomic radius increases, bond length also increases.

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Yes a greater difference in electronegativity typically results in a greater bond dipole moment.

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You can use general trends of electronegativity in the periodic table.

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Anions are polarizable (exhibiting distortion) whereas cations have polarizing power (distorting anions).

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Ions which cause large distortions.

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I believe he said up to Friday's lecture, excluding the last powerpoint slide.

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Electrons will be further away from the nucleus in increasing shells, therefore pull on electrons is less.

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A molecule with resonance has more stability as the multiple bonds can exist in various positions throughout the molecule.

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The expanded octet rule applies for atoms on the periodic table row 3 and beyond because electrons can utilize the d subshell.

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A lone pair is a pair of electrons not shared with another atom.

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Resonance indicates that you can put double bonds in different positions when drawing lewis structures.

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Ionization energy is also important when drawing lewis structures as the atom with the lowest ionization energy is typically drawn as the central atom.

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Typically you choose the atom with the lowest ionization energy as the central atom.

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Electron affinity is essentially the amount of energy spent when an electron is added to a neutral atom, forming an anion.

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l is the angular momentum quantum number or "shape."

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It is a measure of uncertainty since it cannot be exactly determined the momentum and position of a particle simultaneously.

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Hund's rule asserts that due to electron repulsion, electrons in the same subshell occupy different orbitals with parallel spin. Parallel spin indicates that electrons have the same spin whereas 2 electrons with opposite spin are paired.

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It allows us to calculate an electron's wave function.

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What is the difference between the work function and threshold energy?

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Typically, less than the speed of light.

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If threshold energy is surpassed, electrons will be emitted. Given the amount of energy is greater than threshold, the number of electrons emitted is dependent on intensity.

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Any moving particle with momentum, cannot be applied to light.

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Frequency and wavelength are inversely proportional, this can be seen using the formula c = λv.

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I believe he was just trying to give a visual example. When you drop two rocks in the water next to each other, it is easy to see how the waves (ripples in the water) interact with each other and form both constructive and destructive interference.

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Typically when converting between molecules and moles.

1 mole = 6.022 * 10^23 molecules

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Divide by Avogadro's number.

1 mole = 6.022 * 10^23 atoms (molecules)

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My TA said that it may be ordered in any way and will still be an acceptable answer, at least for now.

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I think it is best to use the entire figure given, then round the final answer based on sig figs.

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(m.s^-1) is a different way of expressing (m/s); the meaning is the same.

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