CHEMISTRY COMMUNITY

jennacostello8

A reaction under kinetic control is one in which the rate at which the products are produced regulates the product ratio. The thermodynamic product is the more durable end result of a chemical reaction. A reaction under the control of thermodynamics is one in which the ratio of the products depends ...

jennacostello8

A zero-order reaction is independent of concentration and proceeds at a constant rate. A first-order reaction depends on the concentration of one of the reactants. A second-order reaction rate is proportional to the square of the concentration of a reactant or the product of the concentration of two...

jennacostello8

An extensive property relies on the amount of matter in a sample (such as mass or volume). An intensive property depends only on the type of matter in a sample and not on the amount. Hope this helps!

jennacostello8

The balanced equation would be Cl2O7(g)+4H2O2(aq)+2OH−(aq)⟶2ClO−2(aq)+4O2(g)+5H2O(l). The reduction part of the equation, chlorine changed from +7 to +3. Next, balance the atoms of each half‑reaction. Balance every element other than oxygen or hydrogen first. Then, use H2O to balance the oxygen atom...

jennacostello8

The energy that can be used for work is known as Gibb's free energy. Hence, the value of work will be zero if there is no energy available to do any work.

jennacostello8

When the system is in equilibrium, there is no change in the entropy of the universe. If the system's states remain the same, there is no impact on the surroundings.

jennacostello8

Spontaneous reactions will have a negative Gibbs free energy value, a negative change in enthalpy, a positive E value, or a positive entropy change. Hope this helps!

jennacostello8

The sign of the w value will determine if the system is doing work on the surroundings or system. If w is positive, work is being done on the system. If w is negative, work is done on the surroundings.

jennacostello8

The oxidation number is zero for any compound that is in its neutral form (such as O2 or Cl2).

jennacostello8

Any adiabatic process has q = 0 because there is no heat transfer between the system and its surroundings. Hope this helps.

jennacostello8

Heat is a type of energy, whereas enthalpy specifies the amount of heat transmitted during a chemical reaction at constant pressure. Hope this helps!

jennacostello8

The lines in the heating curve are horizontal because there is no change in temperature during phase shifts. Despite the fact that there is no change in temperature, the length of the horizontal lines show a change in heat. The line will be longer if there is a higher shift in heat. Hope this helps!

jennacostello8

When conditions in the equation are ideal, we use PV=NRT.

jennacostello8

In order to increase internal energy, there are three things that you can do. First, you can add or remove heat. Second, you can add or remove matter. Last, you can do work on or have the system do work. Hope this helps!

jennacostello8

In isolated systems, energy is always conserved. Nothing (such as energy) goes in or out of the system.

jennacostello8

How do we know when something is an oxidation or reducing agent/how can we solve for this?

jennacostello8

When the equilibrium constant is large (10^3 and above), products are favored and the reaction shifts right.

jennacostello8

With Le Chatelier's Principle, a pressure increase shows that a shift in equilibrium would occur to the side with the least number of moles of gas. Hope this helps.

jennacostello8

Anytime x is 10^-4 or less, I use the 5% rule to check if I can cancel it out in the denominator. Hope this helps.

jennacostello8

delta H=q when there is constant pressure. Hope this helps!

jennacostello8

Breaking bonds requires energy, forming bonds release energy. Breaking bonds is endothermic, forming bonds is exothermic.

jennacostello8

If work is done on the system, the sign is positive. If work is done by the system, the sign is negative. Work is done by the system if system volume expands against a force. Work is done on the system if system volume contracts under a force.

jennacostello8

It should be given on our equations sheet. The conversion is 1 bar = 0.986923 atm.

jennacostello8

Negative enthalpy is an exothermic while positive enthalpy is endothermic. Hope this helps!

jennacostello8

Le Chatelier's principle states that if equilibrium is disrupted by changing the conditions, the reaction shifts to counteract the change to reestablish an equilibrium.

jennacostello8

K is only affected by temperature change.

jennacostello8

I would definitely recommend memorizing the strong acids/bases. For bases, I memorized groups 1 and 2 elements attached to OH-. For acids, I used the acronym "So I Brought No Clean Clothes" for H2SO4, HI, HBr, HNO, HCl, HClO4, HClO3. Hope this helps!

jennacostello8

Hi! Kc refers to molar concentrations while Kp refers to partial pressures. It is usually identifiable when to use which constant based on what the question is asking.

jennacostello8

Whenever a problem gives me mmol, I usually convert to mol just to be safe. It is usually best to convert to mol.

jennacostello8

For an acid, percent deprotonated= (concentration of A-)/(initial concentration of HA) x 100
when the equation is HA(aq)+H20(l)--->H30+(aq)+A-(aq)

For a base, percent protonated= (concentration of HB+)/(initial concentration of B) x 100
when the equation is B(aq)+H20(l)--->HB+(aq)+OH-(aq)

jennacostello8

Why do chemists find it easy to work with ammonia? It’s pretty basic.

jennacostello8

Chemists are always so happy in the lab because they're in their "element."

jennacostello8

How do we know when to use the quadratic formula in equilibrium questions?

jennacostello8

I am a little confused on how/when to calculate pH vs. pOH. Can someone help me?

jennacostello8

Hi! Getting a negative number in the square root indicates that there is a problem in your solution and you should try to do it again.

jennacostello8

Hi! Reactions can shift due to a multitude of factors and it depends on the reaction. A reaction can shift left when we add product, remove reactant, decrease pressure, or increase temperature.

jennacostello8

Hi! You can receive up to 30 points for chemistry community, meaning 3 posts or replies a week!

jennacostello8

Hi! Based on the given information in the problem, you are able to choose the correct R value. It depends on what unit the question is asking for.

jennacostello8

Hi! Take the values from the "E" portion of the ICE table and rearrange them into a polynomial expression. Plug the values of a, b and c into the quadratic equation.

jennacostello8

Hi! If there are intermediate values of k (meaning they are between 10^-3 and 10^3), neither reactants or products are strongly favored. If k is large (and is 10^3 or above), equilibrium favors products and "sits to the right." If k is small (and is 10^-3 or below), equilibrium favors reac...

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