CHEMISTRY COMMUNITY

Meigan Wu 2E

By the pre-equilibrium approach, we relate the rate laws that might contain intermediates by the equilibrium constant, correct? What happens if a reactant is a solid or liquid? How do we account for them then?

Meigan Wu 2E

How does the Arrhenius equation relate to collision theory, especially in regards to the Boltzmann distribution?

Meigan Wu 2E

Do we need to know how to use and draw P-T graphs?

Meigan Wu 2E

How do we calculate the number of possible orientations or states mathematically when finding the degeneracy? In other words, if degeneracy W = x^(n), where x= number of possible orientations or states and n= # of particles, how do we mathematically find x?

Meigan Wu 2E

How do we know if a reaction can be treated as a pseudo-first-order reaction?

Meigan Wu 2E

Is using the experimental data in rate ratios the only way to determine the order of a reaction? Is there another way to determine the order?

Meigan Wu 2E

How do rate laws relate to temperature in regards to equations?

Meigan Wu 2E

For basic solutions, you first balance the O by using H2O. Then, you balance H by adding H2O to the side of the half reaction that needs H and adding OH- to the other side.

Meigan Wu 2E

Since standard electric potential is an intensive property, it stays the same when the half reaction is balanced.

Meigan Wu 2E

To balance a half reaction in basic solution, you first add H2O to the side with the least amount of oxygen (let's call this side 1) to balance the oxygen. Then, you add H2O on the opposite side (side 2) and add OH- back to the original side (side 1) to balance the H.

Meigan Wu 2E

The oxidation number of hydrogen is +1 except when bonded to metals in binary compounds, which is when hydrogen would have an oxidation number of -1.

Meigan Wu 2E

The oxidation number of oxygen (O) is 2-, except in H2O2 (O2 = 2-) and O2 (O2 = 2-), where O is -1.

Meigan Wu 2E

What really is Gibbs Free Energy, and what does it mean for a negative Gibbs Free Energy to result in a spontaneous reaction?

Meigan Wu 2E

On worksheet 3 Intro to Thermodynamics, problem 7, what equations are we supposed to use? My friend used the information given to make a cross multiplying equation but got an answer of 51.23g instead of 51.14g. How are we supposed to approach this problem?

Meigan Wu 2E

LorenzoDuvergne3I wrote:Where is this discussed in the textbook?

This is from lecture notes.

Meigan Wu 2E

If a system changes its conditions by both volume and pressure, do we have to solve for the entropy for both volume and pressure, even if the entropy is the same value for both conditions, since volume and pressure are inversely proportional?

Meigan Wu 2E

What does it mean that thermodynamic property means a "small" error in S and a statistical property means a "large" error in W in relation to the Boltzmann equation?

Meigan Wu 2E

If a system has a net internal energy change of zero, then the energy transferred by work and heat are equal and opposite of each other.

Meigan Wu 2E

Can someone explain in their own words what the relationship between internal energy, enthalpy, and heat is?

Meigan Wu 2E

The integral of a variable to the (-1) is natural log, which gives the natural log in the work equation for a reversible process.

Meigan Wu 2E

The heat required depends on the amount of substance, so heat capacity is an extensive property.

Meigan Wu 2E

Energy is required to break bonds (positive enthalpy change), while energy is released to form bonds (negative enthalpy change).

Meigan Wu 2E

Delta H naught of a reaction means the reactions are given in their standard state.

Meigan Wu 2E

On Worksheet 2, why is the concentration of CO3 the same as Ka2 for problem 4b?

Meigan Wu 2E

Did anyone happen to get around 0.077g for #2 on the acid-base review worksheet? The key says 0.10g, so I am unsure whether Karen rounded or I did the question incorrectly. I did the same thing at first. Make sure you use the initial concentration of HCOOH and not the equilibrium concentration of H...

Meigan Wu 2E

For number 7 on worksheet 1, why does high temperature favor the formation of bromine atoms if we don't know if the reaction is endothermic or exothermic?

Meigan Wu 2E

Do only reactions using weak acids and bases use an equilibrium arrow?

Meigan Wu 2E

If the problem is asking you to solve for the pH, pOH, or concentration of a reaction involving a weak acid or base, you use an ICE table because you can't assume 100% dissociation. You can tell if the reaction involves a weak acid by looking at the molecules or by the acidic constant if it is less ...

Meigan Wu 2E

What is activity?

Meigan Wu 2E

How do you tell if one equilibrium reaction is more stable than another?

Meigan Wu 2E

What does $P^{\circ}$ mean in the equation for activity?

Meigan Wu 2E

How do we calculate the equilibrium concentrations of the products and reactants? Will they be given?

Meigan Wu 2E

Can someone explain to me how coordination compounds form, especially how transition metals are able to accept electron pairs from ligands?

Meigan Wu 2E

Why can iron in myoglobin form 6 bonds?

Meigan Wu 2E

Is there a method to naming acids, or do we just need to memorize them?

Meigan Wu 2E

Yes, the approximation of the bond angle is acceptable, so < 120 degrees works.

Meigan Wu 2E

Why is HF a weak acid?

Meigan Wu 2E

Can someone explain what delocalized pi bonding is and when does it exist?

Meigan Wu 2E

You check for electronegativity, dipole moments, and then molecular shape to determine is a molecule is polar or nonpolar.

Meigan Wu 2E

Also, sigma bonds are made from hybridized orbitals and pi bonds are made from unhybridized orbitals.

Meigan Wu 2E

If this helps, a sigma bond is made up of hybridized orbitals and a pi bond is made up of unhybridized orbitals

Meigan Wu 2E

In the VSEPR Model, all bonds are treated as equivalent, so no, double bonds (or any type of bonds in general) are not significant to the structure. We only account for the regions of electron density.

Meigan Wu 2E

How do you calculate for the dipole moment of a molecule and use it to determine whether a molecule is polar or nonpolar?

Meigan Wu 2E

For N2O, why is nitrogen the central atom if oxygen has the lower ionization energy?

Meigan Wu 2E

Why do London forces exist?

Meigan Wu 2E

Are resonance structures only in regards to bond location? Do they apply to the positions of lone pair electrons too?

Meigan Wu 2E

If oxygen has a lower ionization energy than nitrogen, why is nitrogen the central atom in the NO2 Lewis Structure? Is it to maintain symmetry?

Meigan Wu 2E

Thanks everyone! I realized that the question involves copper metal, which has resting mass, so we have to use the De Broglie Formula.

Meigan Wu 2E

In the case of Question 3C on Test 2, how do we know when to used the De Broglie equation then?

Meigan Wu 2E

How do you know when to use the De Broglie formula versus the speed of light formula?

Meigan Wu 2E

How do you know the oxidation number for an atom of an element?

Meigan Wu 2E

When drawing a Lewis Structure, how do you know specifically where to bond the atoms? What are the steps to drawing accurate Lewis Structures of atoms bonded together?

Meigan Wu 2E

Why is the Incorrect Atomic Model disproved because the uncertainty in the velocity of the electron is greater than the speed of light? What is important about the speed of light that disproves this model?

Meigan Wu 2E

Why are spectral lines important? Why are the Balmer and Lyman series significant? I know the Balmer series represents visible light, and the Lyman series represents UV light, but why is that important?

Meigan Wu 2E

What does orbital angular momentum show us, and why is it important?

Meigan Wu 2E

What does the principal quantum number (n) refer to? Does it refer to shell size? Could someone give their own explanation of how the quantum numbers n, l, ml, and ms relate to each other, and their purpose in the atomic structure?

Meigan Wu 2E

In the wavefunction of the ground state of the hydrogen atom, where $\Psi$ (r, $\Theta, \Phi$ ) = Ne^(-r/a0), what does N represent? What purpose does N serve?

Meigan Wu 2E

What is the purpose of the particle in a box concept, and what does it tell us exactly?

Meigan Wu 2E

Can someone explain what "quanta" and "quantized" means?

Meigan Wu 2E

Additional Information: one mole of A is mixed with one mole of B. Update after asking a TA: Since the mole ratio between A and C is 2:3, that means 1 mole of A would yield 1.5 moles of C. The mole ratio between B and C is 1:3, which means 1 mole of B would yield 3 moles of C. Therefore, A is the li...

Meigan Wu 2E

5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentration of the solution in the 2nd flask? Molar Masses: K (39.10 g/mol), Mn (54.94 g/mol), O (16.00 g/mol) How do you s...

Meigan Wu 2E

In the balanced equation 2A + 1B ---> 3C, how do you find the maximum product produced?

*This is under Question 30 in the Limiting Reactant Calculations Audio-Visual Focus Topics Post-Assessment.*

Meigan Wu 2E

In the chemical reaction 4NH3(g) + 5O2(g) ---> 4NO(g) + 6H2O(g), how do you find the limiting reactant if 21.4 g NH3 is reacted with 42.5 g of O2? How do you compensate for the mole ratio when calculating?

Meigan Wu 2E

What are the steps to finding the excess of a reactant in a chemical reaction?

Meigan Wu 2E

Do stoichiometric relations and mole ratios describe the same relationship between substances? What are stoichiometric relations used for? Is it just another way to express a mole ratio?

Meigan Wu 2E

Yes, basically the total mass before a reaction is always equal to the total mass after. Also I liked this concept too: in chemical reactions, atoms are not created or destroyed; they are rearranged.

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