CHEMISTRY COMMUNITY

Bella Townsend

Typically, you only ever use celsius is there is a change in temperature (delta T) because then the units don't matter. The difference will be the same.

Bella Townsend

One of the key features of an enzyme which is used as a catalyst is that it is not used up in the reaction. Therefore, it is not in the overall reaction.

Bella Townsend

The order of the reaction depends on the pressures or concentrations of the reactants, while molecularity is the amount of different molecules in the reactants.

Bella Townsend

When add all the steps/reaction mechanisms the catalysts and intermediates cancel out, which means they do not affect the K of the reaction.

Bella Townsend

You could probably recreate a similar solution with controlled reactants to compare to the pond or other uncontrolled solution.

Bella Townsend

In the overall reaction the electrons in the cathode and anode half reactions cancel out.

Bella Townsend

The problem does not depend on the size of the intermediate, just the other reactants

Bella Townsend

through kinetic control the reaction depends on the amount of reactions, but through thermodynamic control the reaction also depends on the concentration of the products.

Bella Townsend

A pH meter measures the acidity of a solution. This can be helpful in an electrical cell (galvanic or concentration) to determine potential, because potential is based on the flow of electrons is related to the concentration of H+ ions as we have seen in redox reactions.

Bella Townsend

the concentration affects the cell potential, and subsequently affects the reaction overall.

Bella Townsend

The second part is not counted. The rate of reaction is determined by the slow reaction.

Bella Townsend

In general short reactions favor kinetic control, while long reactions favor thermodynamic control.

Bella Townsend

Why does increasing the concentration of the reactants not speed up the rate of the reaction for a zero order reaction?

Bella Townsend

In the mechanism steps of a reaction, a catalyst shows up first as a product, but an intermediate shows up first as a reactant.

Bella Townsend

Do concentration cells ever have a positive Ecell? Can a cell be both galvanic and a concentration cell?

Bella Townsend

You can tell by see which one has least gas molecules on right. This makes the reaction more favorable toward the reactants.

Bella Townsend

The Gibbs free energy of a reversible reaction is equal to the max work that can be done at const. temperature and pressure

Bella Townsend

Changes in temperature, concentration, and pressure affect ecell potential.

Bella Townsend

I have this question as well.

Bella Townsend

In a neuron, the concentration of K+ ions inside the cell is about 20-30 times as great as the outside. What potential difference between the inside and outside of the cell would you expect to measure if the difference is only due to the imbalance of potassium ions? The solution manual says that sin...

Bella Townsend

In a reversible reaction there is more work done than in a irreversible reaction. In a reversible reaction the change in temperature is zero, aka an isothermal reaction.

Bella Townsend

In the very back of the book in appendix 2, right after standard enthalpies and entropies

Bella Townsend

Why do pure elements generally have a oxidation number of zero?

Bella Townsend

What is the relationship between deltaG and deltaG knot?

Bella Townsend

What is the original equation that lnK2/lnK1=-dH/R * (1/T2-1/T1) is derived from?

Bella Townsend

3B) Dr. Lavelle picks up the ice cream that he has just heated up (-2.8 oC) and accidentally drops it on the ground and can’t eat it. Tears streaming down his face, he watches as half of it melts away when he realizes that from the moment he dropped the ice cream until now, it has received exactly 2...

Bella Townsend

Some equations you need to know for this equation is when you are calculating the Cpm for a molecule of one type of atom like an ideal gas you use q=n*5/2R*deltaT when you are calculating the Cvm for a molecule of one type of atom like an ideal gas you use q=n*3/2R*deltaT The rest is given to you 76...

Bella Townsend

What sections do we do for homework this week?

Bella Townsend

When enthalpy is positive and delta H is greater than zero, this means that a system absorbed heat, this is a non spontaneous reaction, and the system is doing work on the surroundings when work is negative. When enthalpy is negative and delta H is less than zero, this means that a system released h...

Bella Townsend

you can calculate the change in both enthalpy and entropy. Both enthalpy and entropy are state functions

Bella Townsend

you would use the equation deltaS=nRln(Tfinal-Tinitial)

Bella Townsend

a rule of thumb is:
Expansion is work done by the system
Compression is work done on the system

Bella Townsend

Gibbs free energy with a negative value, is a spontaneous reaction that produces more stable reactants compared to that of a non spontaneous reaction.

At a substances lowest energy state is its most stable configuration.

Bella Townsend

w=-nRTln(v2/v1) is the right equation but first you have to use the equation PV=nRT to find the number of moles
n=PV/RT
1.79 x4.29/0.08206 x 305 x ln 6.59/4.29
=-326J

Bella Townsend

irreversible reaction occur at thermodynamic equilibrium, while reversible reactions do not maintain thermodynamic equilibrium. irreversible reaction are where the products formed do not combine to give the reactants I looked up a reaction online that is an example potassium chlorate decomposes on h...

Bella Townsend

For a, the equation for irreversible expansion is w=-PdeltaV w=-(1atm)(1.2L) w=-122J for b, w=-nRTln(v2/v1) w=-(0.2mol)(8.314)(298.15K)(ln2.40L/1.2L) w=-344J Reversible expansion does more work than irreversible expansion, because when a system does reversible expansion it has to go outside of the t...

Bella Townsend

If you look at a heating curve, the slanted lines represent the temperature increasing, and the flat lines represent the phase change where there is no change in temperature. For example, on the first straight line, the leftmost point represents solid water at 0 degrees celsius, and on the most righ...

Bella Townsend

Due to the law of conservation of energy, the q of the system is equal to the -q of the surroundings. So when you use a bomb calorimeter, you combust the substance inside. Therefore, the q of the substance is equal to the -q of the bomb calorimeter.

Bella Townsend

Delta H is Kilojoules per mole because it is the amount of heat that is required for a particular substance to form, vaporize, sublimate etc.
Q is KJ to measure heat transferred between two systems

Bella Townsend

K is the constant of a certain reaction when it is in equilibrium
Q is the quotient of products and reactants at any stage of a reaction
Q=K the reaction is at equilibrium
Q>K the reaction favors the reactants
Q<K the reaction favors the products

Bella Townsend

it is exactly the same, we are just apply it to phase changes now

Bella Townsend

there are multiple ways to calculate enthalpy, but only one way to calculate heat

Bella Townsend

the scale is relative. the smaller the K value the stronger the acid.

Bella Townsend

there are multiple ways to get to the right conclusion with a state function. Multiple variables contribute to the calculation of a state function.

in a path function, how you get the answer matters. There is only one way to calculate a path function

Bella Townsend

Endergonic and endothermic have the same meaning, endergonic refers to gibs free energy and endothermic refers to the enthalpy.

Bella Townsend

for the reaction 2HD(g)+H2(g)⇌D2(g), H2 is an inert gas and it does not affect the reaction. Typically noble gases in reactions are inert gases. the reaction Cl2(g)⇌2Cl(g) goes from 1 mole Cl in the reactants, and 2 moles Cl in the products. Le chatelier's principles says that the reaction goes to t...

Bella Townsend

Inert gases do not react, and therefore do not affect the partial pressures of the other products and reactants.
Inert gases do not affect the volume and pressure of the reaction.

Bella Townsend

Adding heat is like adding another reactant and when you increase the number of reactants the reaction shifts to the right.
Releasing heat is adding to the products side of the reactions, when you increase the products, the reaction shifts to the left.

Bella Townsend

Kw= Ka x Kb
Ka and Kb have to be a conjugate acid and base pair

Bella Townsend

I'm confused on the meaning on Kc and the difference between Kc and K with other subscripts.

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