CHEMISTRY COMMUNITY

Isabelle Fontanilla 1I

You can also look at the rate values(if given) and compare--the bigger the rate, the faster it is. The rate constant, k, is directly proportional to the rate, so the bigger the k, the bigger the rate=faster reaction. The rate determining step, being the slowest, should usually have the smallest k an...

Isabelle Fontanilla 1I

No, unless the problem states for you to use standard concentrations.

Isabelle Fontanilla 1I

Work done by the system results in a loss of energy from the system. This means that the internal energy is decreasing due to work. As a result, work is negative. Work being done on the system by outside forces means that energy is being inputted into the system. This makes the work positive.

Isabelle Fontanilla 1I

Negative integer: A negative order indicates that the concentration of that species INVERSELY affects the rate of a reaction.
So, yes, if a species has a negative order, then it participates in a reverse reaction, thereby leading to a decrease in the reaction rate(slowing it down).

Isabelle Fontanilla 1I

He said that he just showed us how the equations are derived to help us understand the concept behind each of them. We only need to know the final forms and their applications.

Isabelle Fontanilla 1I

Also, the book says that the unique average rate "does depend on the coefficients used in the balanced equation." Why is this the case? I thought unique average rate of change takes care of the stoichiometric coefficient differences between the reactions and products?

Isabelle Fontanilla 1I

Cu2+(aq) being a better oxidizing agent means that it wants electrons more than H+(aq), meaning that it has greater affinity with electrons/attracts electrons more. This means that it is more likely for Cu2+(aq) to be reduced than H+(aq). So, Cu2+(aq) is more likely to reduce itself(gain electrons) ...

Isabelle Fontanilla 1I

Significant figures are usually derived from the problem itself. Using the Nernst Equation should not be the determinant of how many significant figures will be used for K.

Isabelle Fontanilla 1I

Yes, the reaction should be favorable in the reverse direction.

Isabelle Fontanilla 1I

O2 will have an oxidation number of 0 because it is in its elemental form.
Oxygen will have a -1 ON when it is found in peroxides (e.g. H202).
Everything else will yield a -2 ON for Oxygen.

Isabelle Fontanilla 1I

Can someone explain why max cell potential is achieved when there is very little current flow?

Isabelle Fontanilla 1I

Yes, the anode is always reversed because we always flip the reaction that is being oxidized(located at the anode). When the voltage is negative, it means that the reaction is not spontaneous because ΔG is negative. Since a normal battery reaction is spontaneous(via the galvanic cell), we want posit...

Isabelle Fontanilla 1I

So far, the only type of work we talked about is work through expansion/compression. For this, you only really need to remember(and understand) the work equation at constant pressure (w=-PΔV) and the work equation for reversible and isothermic configurations (w=-nRTln(V2/V1)).

Isabelle Fontanilla 1I

"At constant temperature and pressure, the direction of spontaneous change is the direction of decreasing Gibbs free energy."
The more negative the Gibbs Free Energy value is, the more spontaneous a process becomes.

Isabelle Fontanilla 1I

What does it mean when Gibbs Free Energy changes? How does this affect the system?

Isabelle Fontanilla 1I

Can someone define heat, enthalpy, temperature, and work?

Isabelle Fontanilla 1I

Why is heat, like work, not a state function?

Isabelle Fontanilla 1I

Should q(heat) be in kJ or J?

Isabelle Fontanilla 1I

Are we required to know the different types of work listed on Table 4A.1 (7th Edition) such as expansion, extension, raising weight, electrical, and surface expansion along with their formulas and units?

Isabelle Fontanilla 1I

Can you give an example of a system that is doing a free expansion?

Isabelle Fontanilla 1I

What would happen to the equilibrium of a system if an inert gas is added into it while keeping the volume constant? What would happen if the inert gas is added while the volume is allowed to change? Also, wouldn't adding additional gas particles within a system lead to an overall increase in the pr...

Isabelle Fontanilla 1I

Adding catalysts does not change the equilibrium because all it does is speed up the rate at which the system reaches equilibrium by lowering the activation energy required to proceed with the reaction(forward reaction rate and reverse reaction rate are changed equally). Also, catalysts do not chang...

Isabelle Fontanilla 1I

Given the K value, if K<<10^-3, then you may make the approximation. If K is not given, then make the approximation, but be sure to check if the value of x that you found is, indeed, less than 5% of the initial value(s)(concentration/partial pressure)of the components in the system. If x<5% of the i...

Isabelle Fontanilla 1I

When an inert gas is added to a system in equilibrium with constant volume, the pressure of the system will go up, but, since the concentrations of the products and reactants do not change, there will be no shifts in the equilibrium. However, if the volume is not constant, the equilibrium will shift...

Isabelle Fontanilla 1I

Will there be a difference in effects if the pressure of the entire system is changed instead of changing only the partial pressure of the components of the system?

Isabelle Fontanilla 1I

Can someone explain the reasoning behind the shortcut method which can be used to bypass the quadratic equation when solving for the change in molarity(x)?

Isabelle Fontanilla 1I

If the equilibrium constant is equal to 1, what does it mean? Does it mean that the system is at equilibrium?

Isabelle Fontanilla 1I

Why are aqueous solutions used when determining the equilibrium constants, while liquids are not?

Isabelle Fontanilla 1I

Also, the constants sheet should have the gas constant, R, on it. For this, use the most appropriate form so you will have common units. As for temperature, T, it should be given in the problem. Like the previous answer stated, use the Ideal Gas Law to convert between concentration and partial press...

Isabelle Fontanilla 1I

Brackets indicate the concentration of whatever is inside the brackets. This means that you're solving for Kc.
Parenthesis just indicates groupings and multiplication. This is not conclusive in that you can be dealing with partial pressures or concentrations.

Isabelle Fontanilla 1I

Why is an oxoacid stronger with more oxygens?

Isabelle Fontanilla 1I

Why is perchloric acid considered a strong acid?

Isabelle Fontanilla 1I

All polydentate ligands will have prefixes bis, tris, etc. whenever more than one of them is involved. Ligands do not necessarily have to have the prefixes bi, tri, tetra, etc. to get the prefixes(bis, tris, etc.).

Isabelle Fontanilla 1I

No, the charges in acid and base reactions are not found by calculating formal charges. The charges are based on the properties of the elements themselves(electronegativity, electron affinity, ionization energy, etc.). The charges are basically derived from the fact that elements either gained or lo...

Isabelle Fontanilla 1I

How is it possible for certain elements to have more than one possible ion(different charges), like Ti +2, +3,+4?

Isabelle Fontanilla 1I

How does polarity affect the strength of intramolecular force?

Isabelle Fontanilla 1I

Based on the rule: like dissolves like, I know that polar solvent dissolves polar compounds. However, I do not know how non-polar solvent dissolves non-polar compounds. Can someone explain? Is it because of London Dispersion Forces? If so, won't non-polar solvent still be able to dissolve polar comp...

Isabelle Fontanilla 1I

When ionic compounds exhibit covalent properties(cation attract the electrons of the anion), is the polarity of the anion affected?

Isabelle Fontanilla 1I

Can someone explain the concept/mechanics behind bond energies? Why is energy released when a bond is formed? Conversely, why is energy needed in order for a bond to break?

Isabelle Fontanilla 1I

@katie_sutton1A
As of November 18, 2018, we should have 21 posts.

Isabelle Fontanilla 1I

I think we pretty much have to memorize the conditions for each shape. Making use of the VSEPR notation helps a lot, but it still requires that you know the conditions of each shape. As for trends, I am not aware of any existing.

Isabelle Fontanilla 1I

Can someone explain what a distorted electron is? Also, how does it relate to polirizability?

Isabelle Fontanilla 1I

How does increasing the molar mass result in stronger attractive interactions in this type of force(Induced Dipole - Induced Dipole)?

Isabelle Fontanilla 1I

Why is the solubility among the silver halides (from AgF to AgI) decreasing(less soluble) as the size of the anion gets bigger? I thought that increasing the size of the components of a compound increases the compound's solubility(more soluble) because the bond holding it together gets weaker due to...

Isabelle Fontanilla 1I

What exactly are covalent characteristics? From the Na+ Cl- example, is the electrostatic pull of the cation, Na+, on the electrons of the anion, Cl-, the covalent characteristic? If so, are there others? Also, what is the ionic characteristic of this example?

Isabelle Fontanilla 1I

A specific valence electron must be specified. For example, 2p^ 6 . In this case, the 3 orbitals of the p subshell(px,py, and pz) must be filled accordingly by following the Pauli Exclusion Principle and the Hund's Rule. Distribute the electrons, using up and down arrows to represent the electron sp...

Isabelle Fontanilla 1I

I know someone already asked this, but no one has answered it yet, so... The problem is asking which element in each of the following pairs have higher electron affinity. a. Te or I b. Be or Mg c. O or S d. Ga or In Why does Sulfur have a higher electron affinity compared to oxygen? I thought electr...

Isabelle Fontanilla 1I

When comparing elements based on the different periodic trends, how do you decide which of the two elements diagonal to one another is going to have a larger value than the other? Like, for example, when comparing the ionization energies of lithium and magnesium, fluorine and arsenic, selenium and i...

Isabelle Fontanilla 1I

Thanks! Then can you also explain why group 15 elements with half-filled valence p shell have lower ionization energy than the group 17 elements with the almost-filled(just needs 1 more electron to fill up)p shell? Does it have to do with increased electrostatic attraction between the nucleus and th...

Isabelle Fontanilla 1I

According to the first ionization energy periodic table trend, a movement from the left side to the right side of the periodic table will yield increasing ionization energy values. However, when I looked up the actual first ionization energies of the different elements I found that some elements fro...

Isabelle Fontanilla 1I

While I know that electron shells fill up based on the Aufbau principle(lower energy levels fill up before higher energy ones), I do not understand how the 4s becomes higher energy after it fills up and 3d becomes lower energy. I also don't understand why elements before atomic number 21 fill in the...

Isabelle Fontanilla 1I

How are the magnetic quantum numbers derived? Also, how are the quantum numbers connected to the Schrödinger Wave Equation?

Isabelle Fontanilla 1I

Can someone explain why the answer to this problem is: c) "The extent of the change in the electrical field at a given point decreases"? I know that the other choices are wrong, but I don't know how to explain that this choice is right. The problem reads: "Which of the following happe...

Isabelle Fontanilla 1I

For any of the upcoming tests, do we have to memorize the different Spectral Series? Which aspects do we have to know by heart?

Isabelle Fontanilla 1I

When an electron moves up to its highest energy state, is it possible for that electron to lose just a part of the energy it gained, or does it have to lose all of it?

Isabelle Fontanilla 1I

During lecture we talked about how in order to find the wavelengths of the different electromagnetic radiation within the EM Spectrum, white light is passed through a glass prism. How can white light possess different wavelengths of light? Also, why is black light not used?

Isabelle Fontanilla 1I

If you posted more than 3 times on Chemistry Community in one week, will the posts that went over the weekly post requirement be counted for next week's post requirement?

Isabelle Fontanilla 1I

Why do we fill out the 4s orbital first before filling out the 3d orbital?

Isabelle Fontanilla 1I

In this combustion reaction: CH4 + 2O2 → CO2 + 2H20 (or any chemical reactions, really), I've been hearing people read it as "1 mole of CH4 reacts with 2 moles of Oxygen to produce 1 mole of CO2 and 2 moles of H2O," while some also read it as "1 molecule of CH4 reacts with 2 molecules...

Isabelle Fontanilla 1I

What will you have to do if the mass percent of the different elements that make up a compound/molecule does not add up to 100%? Like, for example, if the percent composition is, like, 41% C, 25% O, and 22% H. 41+25+22≠100. Also, is it alright to assume that a 99.96% composition is close enough to 1...

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