CHEMISTRY COMMUNITY

Gurmukhi Bevli 4G

For Q=K, the reaction is at equilibrium
For Q>K, the forward reaction is favored (towards the products)
For Q<K, the reverse reaction is favored (towards the reactants)

Gurmukhi Bevli 4G

You can approximate the x value provided K<10^-4 (or smaller), and as already stated, you can cross check using the 5% ionization rule.

Gurmukhi Bevli 4G

^ Your work seems to be right.

Gurmukhi Bevli 4G

Temperature affects the forward and reverse reaction rates, which subsequently affects the rate constant (for K=k/k’ and k = rate constant). So when temperature changes, the rate constant, (and K) also changes.

Gurmukhi Bevli 4G

You can determine them using Q and K, for Q>K, the reaction favors reactants and moves left, for Q<K, it favors products and proceeds to the right.

Gurmukhi Bevli 4G

Kw is the equilibrium constant for water, and the w subsequently refers to water.

Gurmukhi Bevli 4G

Find both the K and Q values, and see which one is larger. For Q>K, the reactants are favored and the reaction will shift to the left, for Q<K, products are favored, and the reaction will proceed to the right.

Gurmukhi Bevli 4G

Since the Ca(OH)2 gets dissolved in water, it is an aqueous solution, which makes it included within the equilibrium constant calculation.

Gurmukhi Bevli 4G

Provided they are in a gaseous or aqueous state, but not if they are liquids or solids.

Gurmukhi Bevli 4G

Ideal gases do not take up space/volume, and don't have any interaction (no intermolecular forces of attraction). They have to satisfy/follow the (ideal) gas laws essentially.

Gurmukhi Bevli 4G

It will normally depend on the units given for the other quantities being used in the problem, and the variations of R and its value/units will usually be given on the formula sheet, so it is easier to assess the units on a case by case basis and see which one is the best fit.

Gurmukhi Bevli 4G

I would keep it in Kelvin at all times, just to be safe.

Gurmukhi Bevli 4G

If you decrease the volume of a system, the same number of particles (or moles of a substance) will suddenly have more opportunities to collide (the frequency of their collisions will increase), which will increase the pressure of the system. The system will want to nullify this change and return to...

Gurmukhi Bevli 4G

Assuming you are talking about the ideal gas law, in which case yes, you can use the equation to find a value like moles when given temperature, pressure, and volume. In regards to the second part of your question, I don't think you would be able to use the given equation to find initial and final c...

Gurmukhi Bevli 4G

In both cases, you are balancing O and H, when balancing acidic reactions, add H+ protons (to balance H) and H2O (to balance O), and for basic reactions, add OH- ions and H2O.

Gurmukhi Bevli 4G

The temperature should be in kelvin.

Gurmukhi Bevli 4G

At constant pressure, the value of q will equal H, and The equation U=H-PVdv should be used.

Gurmukhi Bevli 4G

Water (and solids) are not included in the calculation of an equilibrium constant, and adding water should not shift the reaction in either direction since it is omitted from the equilibrium concentration and reaction direction calculations to begin with.

Gurmukhi Bevli 4G

Water (and solids) are not included in the calculation of an equilibrium constant, and adding water should not shift the reaction in either direction since it is omitted from the equilibrium concentration and reaction direction calculations to begin with.

Gurmukhi Bevli 4G

I think it should be 10^-3<k<10^3 where k values less than 10^-3 are considered small, and k values bigger than 10^3 are considered large.

Gurmukhi Bevli 4G

I don't think there is a specific list you have to memorize, but knowing/understanding the examples Dr. Lavelle mentions in class should be useful.

Gurmukhi Bevli 4G

Generally the problem should specify which one it is. If not, for a reversible expansion, Psystem = external pressure, which will decrease as the expansion takes place. For an irreversible expansion, the external pressure will be constant.

Gurmukhi Bevli 4G

Adding an inert gas will change the pressure of the system (increase it), but will not affect the K and Q values (does not change the equilibrium concentration), and will not have an effect on the overall reaction.

Gurmukhi Bevli 4G

Sapling learning and the textbook questions have both been really helpful! Khanacademy has also been useful for understanding certain concepts.

Gurmukhi Bevli 4G

You would need to use an ICE table for part b, to find the eventual equilibrium concentrations of the substances involved.

Gurmukhi Bevli 4G

They are (hypothetical) gases that do not have many interactions and take up very little space (and follow the gas laws perfectly). They are considered hypothetical since they do not occur naturally (very often).

Gurmukhi Bevli 4G

The pH will always be calculated at equilibrium, subsequently the H+ value will also be at equilibrium.

Gurmukhi Bevli 4G

Yes, you can use this equation at STP.

Gurmukhi Bevli 4G

Yes I think thats possible, provided you have been given enough information.

Gurmukhi Bevli 4G

Yes, since that R-value is in J/Kmol (or kJ/Kmol), which can be cancelled out to give you an appropriate value (in units) for G (J/mol).

Gurmukhi Bevli 4G

I don't think it matters provided your units stay consistent throughout the entire problem. If J/kJ are necessary the problem will probably specify which unit it wants/if it wants you to convert between units.

Gurmukhi Bevli 4G

The value of state functions are independent of pathways taken to reach their initial/final values. Since pathway becomes inconsequential, the quantity is only dependent on initial and final values.

Gurmukhi Bevli 4G

q=-w when the internal energy of a system is 0, (normally q=U-w). This happens when an isothermal reversible expansion is taking place since work is being done by the system (and heat is leaving the system).

Gurmukhi Bevli 4G

An adiabatic process has no heat transfer (q=0)

Gurmukhi Bevli 4G

It depends but generally it would be positive when work is being done on the system and negative when the system is performing work on the surroundings

Gurmukhi Bevli 4G

There is no difference, they are the same thing.

Gurmukhi Bevli 4G

State functions deal with the initial and final values of a system, but are not interested in the path taken by systems to reach those values.

Gurmukhi Bevli 4G

I don't think we will need to memorize them, most values we need should be given to us on the formula sheet.

Gurmukhi Bevli 4G

w represents work and is expressed in joules.

Gurmukhi Bevli 4G

A closed system can exchange energy with its surroundings, an isolated system cannot exchange energy or matter with its surroundings.

Gurmukhi Bevli 4G

I think they would most likely be given on the formula sheet, I would memorize the value for water just in case.

Gurmukhi Bevli 4G

It would be positive since work is being performed on the system.

Gurmukhi Bevli 4G

I would just stay consistent with whatever units the problem gives you.

Gurmukhi Bevli 4G

Can someone explain why its called a bomb calorimeter again?

Gurmukhi Bevli 4G

It can be used to convert between partial pressure and concentration, since n/v (mol/L) is equal to concentration, for pv=nRT, n/v=P/RT.

Gurmukhi Bevli 4G

Increasing temperature decreases k for an exothermic reaction (which releases energy), and increasing temperature increases k for an endothermic reaction (which requires energy).

Gurmukhi Bevli 4G

You cannot calculate K for an unbalanced equation, but unless you know the reaction is at equilibrium, you would be calculating Q for a balanced reaction as well. For both the Q and K cases, your reaction still needs to be balanced.

Gurmukhi Bevli 4G

Kc is used when you're dealing with molar concentrations, or when all the substances in your reaction are aqueous. Kp is used for partial pressures, or when the substances in your reaction are all gases.

Gurmukhi Bevli 4G

State properties are values that are dependent on a final condition rather than the path taken to reach that condition. So their value would be the same no matter what method you use to get to your final value (similar to the mountain climbing analogy used in class, where the route taken doesn't mat...

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