## Search found 51 matches

Fri Mar 13, 2020 10:56 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysis
Replies: 11
Views: 40

### Re: Catalysis

Catalysis is when the rate of a reaction is increased by decreasing the necessary activation energy of a reaction through the use of a catalyst such as an enzyme.
Fri Mar 13, 2020 10:53 am
Forum: First Order Reactions
Topic: Difference between first and second order
Replies: 6
Views: 18

### Re: Difference between first and second order

The rate of a first order reaction depends only on the concentration of one reactant. However, the rate of a second order reaction depends on the concentration of two reactants to the first power or one reactant to the 2nd power.
Fri Mar 13, 2020 10:51 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Boltzmann Distribution
Replies: 2
Views: 10

### Re: Boltzmann Distribution

The Boltzmann Distribution shows the distribution of the energy of particles based on their temperature. Similarly, the Arrhenius equation gives the rate of a reaction in terms of its activation energy and temperature. Both show the relationship between activation energy/kinetic energy and temperatu...
Fri Mar 13, 2020 10:36 am
Forum: Balancing Redox Reactions
Topic: OH vs H
Replies: 12
Views: 76

### Re: OH vs H

You have to as balancing in a basic solution requires the same steps as balancing in an acidic solution, however, at the end you have to neutralize the H+ with OH- for a basic solution.
Fri Mar 13, 2020 10:34 am
Forum: Reaction Mechanisms, Reaction Profiles
Replies: 3
Views: 15

Absorption is when something takes in something else like a sponge absorbing water. Adsorption on the other hand is when a reactant sits on the surface of a catalyst.
Mon Mar 09, 2020 10:50 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: gibbs free energy
Replies: 15
Views: 96

### Re: gibbs free energy

Gibbs free energy is the energy available to do work or the useable energy.
Mon Mar 09, 2020 10:44 am
Forum: Zero Order Reactions
Topic: Order of Reaction
Replies: 3
Views: 20

### Re: Order of Reaction

Yes, by comparing equations with rates and concentrations for different experiments as we did in class you can find the exponents for the differential rate laws and the exponent directly corresponds to the order of the reaction.
Mon Mar 09, 2020 10:41 am
Forum: Phase Changes & Related Calculations
Topic: Absorb means "+"?
Replies: 4
Views: 62

### Re: Absorb means "+"?

While the outside system is absorbing the heat (+q, you are looking at the system itself, not the surroundings meaning the heat released
into the system is -q of the surroundings.
Mon Mar 09, 2020 10:32 am
Forum: General Rate Laws
Topic: Enzyme saturation
Replies: 6
Views: 25

### Re: Enzyme saturation

If an enzyme is saturated, the rate will not change no matter how much substrate is added since the enzyme is already fully reacting and being used.
Mon Mar 09, 2020 10:30 am
Forum: General Rate Laws
Topic: Elementary reactions
Replies: 5
Views: 17

### Re: Elementary reactions

An Elementary reaction is a single step reaction.
Sat Feb 29, 2020 11:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridges
Replies: 11
Views: 70

### Re: Salt bridges

The salt bridge neutralizes the cell so there is no longer buildup of charges. This allows the battery to last for longer as the flow of electrons can continue.
Sat Feb 29, 2020 11:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: No Salt Bridge
Replies: 7
Views: 36

### Re: No Salt Bridge

Since the anode is the reaction being oxidized, the electrons flow from the anode side to the cathode side, leaving behind positive ions on the anode side and more electrons (more negative charge) on the cathode side.
Sat Feb 29, 2020 11:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode vs Cathode
Replies: 5
Views: 21

### Re: Anode vs Cathode

The anode is the half-reaction being oxidized and the cathode is the half-reaction being reduced.
Sat Feb 29, 2020 10:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Units for delta G
Replies: 14
Views: 125

### Re: Units for delta G

The units will just be in kJ since the units in n and F cancel in terms of moles.
Sat Feb 29, 2020 10:52 pm
Forum: Balancing Redox Reactions
Topic: Reducing/Oxidizing Agents
Replies: 13
Views: 57

### Re: Reducing/Oxidizing Agents

The reducing agent is the species being oxidized as it reduces the other species by transferring its own electrons to something else, therefore reducing it. The oxidizing agent is very similar in terms of logic but it is the opposite.
Wed Feb 26, 2020 1:14 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Porous Disk and Salt Bridge
Replies: 13
Views: 368

### Re: Porous Disk and Salt Bridge

I think they both serve the same purpose of reducing charge buildup so one is not much more effective than the other.
Wed Feb 26, 2020 1:11 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Which one is Product? Cathode or Anode?
Replies: 5
Views: 47

### Re: Which one is Product? Cathode or Anode?

The anode is being degraded and product builds up at the cathode.
Wed Feb 26, 2020 1:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potential
Replies: 2
Views: 53

### Re: Standard Cell Potential

There are multiple ways to find E. One way is by balancing and adding together the half reactions and in that case you would need to flip the sign of one E˚. However, if you are given E˚ for each half reaction E˚ = E˚ cathode - E˚anode and in that way you simply subtract the standard cell potentials.
Wed Feb 26, 2020 1:07 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: log or ln
Replies: 6
Views: 45

### Re: log or ln

Both can be used there is just a necessary conversion factor required to convert from ln to log.
Wed Feb 26, 2020 1:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic vs. Concentration Cells
Replies: 6
Views: 37

### Re: Galvanic vs. Concentration Cells

A Galvanic Cell relies on different metal electrodes for the flow of electrons where as concentration cells rely on different concentrations of the same metal in the electrodes to drive the flow of electrons.
Sat Feb 15, 2020 5:28 pm
Forum: Van't Hoff Equation
Topic: Equation
Replies: 5
Views: 32

### Re: Equation

This equation allows you to determine whether a reaction is endo or exergonic based on the values and signs of ∆H and ∆S.
Sat Feb 15, 2020 5:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs and K value
Replies: 3
Views: 34

### Re: Gibbs and K value

If the reaction is at equilibrium, then Q = K, so you can substitute in K for Q and the ∆G will depend on K.
Sat Feb 15, 2020 5:21 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: degeneracy W
Replies: 7
Views: 67

### Re: degeneracy W

Degeneracy is the number of states possible to the power of the number of particles. Thats why you can have avogadro's number if you are looking at the degeneracy of one mole.
Sat Feb 15, 2020 5:19 pm
Forum: Balancing Redox Reactions
Topic: redox reactions
Replies: 3
Views: 23

### Re: redox reactions

Redox reactions occur when electrons are transferred from one molecule to another in a chemical reaction. That is why when one species os oxidized, the other species is reduced. Reduction is when electrons are gained and oxidation is when electrons are lost.
Tue Feb 11, 2020 7:50 pm
Forum: Administrative Questions and Class Announcements
Replies: 67
Views: 2562

Can someone also explain #12B? Is there a specific equation to use?
Tue Feb 11, 2020 7:49 pm
Forum: Administrative Questions and Class Announcements
Replies: 67
Views: 2562

Can someone explain how to solve #11 on the practice questions? What steps do you need to take?
Sat Feb 08, 2020 4:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: biological examples
Replies: 2
Views: 34

### Re: biological examples

Since ATP hydrolysis is an exothermic and exergonic reaction, it can be coupled to endothermic reactions to provide the energy needed for the endergonic reaction to be completed in processes like cellular respiration. Because of energy coupling, it can also allow coupke reactions to have an overall ...
Sat Feb 08, 2020 4:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeters
Replies: 17
Views: 97

### Re: Calorimeters

It is a constant volume calorimeter.
Sat Feb 08, 2020 4:55 pm
Forum: Calculating Work of Expansion
Topic: Reversible Process and Work
Replies: 4
Views: 41

### Re: Reversible Process and Work

For reversible processes, the temperature remains constant while the pressure and volume change inversely to each other. In this way, the curve has pressure changing as volume changes, so the area under the curve is larger than that of an irreversible process in which external pressure stays constan...
Sat Feb 08, 2020 4:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: State Property
Replies: 5
Views: 30

### Re: State Property

A state property is one which is additive such as enthalpy or free energy. So, enthalpy relates to state functions as it is one as shown by Hess' Law.
Sat Feb 08, 2020 4:49 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Reversible vs Irriversible
Replies: 3
Views: 28

### Re: Reversible vs Irriversible

An Irreversible reaction occurs when the external pressure of the surroundings and temperature remain constant and the volume of the system is changed, therefore changing the internal pressure of the system. In the case of irreversible reactions, there is no equilibrium possibility and the equation ...
Sat Feb 01, 2020 6:46 pm
Forum: Phase Changes & Related Calculations
Topic: DELTA H Vs Q
Replies: 7
Views: 48

### Re: DELTA H Vs Q

Yes, the ∆H of a reaction depends on the number of moles being reacted as the ∆H represents how much heat is required or released per mole of reactant/product. However, q represents the heat required or released in a system based on the number of moles or mass in a reaction.
Sat Feb 01, 2020 6:43 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Two-State System
Replies: 1
Views: 27

### Re: Two-State System

If there are two spaces that can be inhibited, the two particles can either both be in side 1 or both be in side two as well as one in each. The reason why it is four states and not 2 is that the side the particle inhibits matters and so there are more permutations possible.
Sat Feb 01, 2020 6:42 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: insignificance of pdeltav
Replies: 1
Views: 14

### Re: insignificance of pdeltav

P∆V represents the pressure of the system times the change in volume, also known as work. However, when you are looking at solids and liquids in reactions, the volume of such substances does not change by very much at all, so you can think of it as assuming ∆V goes to 0, which cancels out the entire...
Sat Feb 01, 2020 6:40 pm
Forum: Calculating Work of Expansion
Topic: Gas constant
Replies: 5
Views: 37

### Re: Gas constant

When choosing a gas constant, you need to look at the units in the problem. Since you are given atm, use the gas constant 0.0821.
Sat Feb 01, 2020 6:38 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: using entropy
Replies: 1
Views: 18

### Re: using entropy

Entropy is a measure of disorder and is used when finding Gibb's free energy instead of just ∆H and the heat of a reaction. Entropy is used a lot in the law of thermodynamics as one of the laws says that the universe tends towards disorder and chaos, meaning a higher entropy.
Fri Jan 24, 2020 4:04 pm
Forum: Ideal Gases
Topic: pressure
Replies: 10
Views: 72

### Re: pressure

The total pressure is the pressure of the entire system, whereas each gas making up the system has its own partial pressure, which makes up the total pressure. If you had a container with O2 and H2 gas is it and the partial pressure of each gas was 0.5 atm, the total pressure would be 1 atm.
Fri Jan 24, 2020 4:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Steam
Replies: 5
Views: 26

### Re: Steam

Even though the temperature of the system doesn't increase in the vaporizing transition state, heat is still increasing as energy is applied to the system. So, when the steam comes in contact with your skin and condenses, all of the energy stored in the bonds gets transferred to your skin and the wa...
Fri Jan 24, 2020 3:58 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Transition Temp.
Replies: 6
Views: 50

### Re: Phase Transition Temp.

Not seeing a temperature change does not mean that there is no change in heat occurring. As the temperature of a system is increased, more heat is being applied and in the normal states, the temperature will increase, but when it comes to transition states, a lot of energy is required for the transi...
Fri Jan 24, 2020 3:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpy Accuracy
Replies: 6
Views: 25

### Re: Bond Enthalpy Accuracy

Bond enthalpies of diatomic molecules are completely accurate, but for all other bonds formed the bond enthalpy given is an average of all different bonds of that nature that occurred instead of the actual value for that specific bond or reaction, so there is some error, making it the least accurate.
Fri Jan 24, 2020 3:53 pm
Forum: Phase Changes & Related Calculations
Topic: Constant pressure and constant volume
Replies: 3
Views: 43

### Re: Constant pressure and constant volume

Constant volume refers to the size of the container staying the same whereas constant pressure refers to the pressure staying the same as a result of the number of moles or volume staying the same while other factors change.
Wed Jan 15, 2020 11:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ice Box
Replies: 9
Views: 70

### Re: Ice Box

The negative change is given to the reactant when you are given an initial concentration of reactants at the beginning because the system is proceeding from there. However, if you were given products and the reverse reaction were to occur to reach equilibrium, the negative change would be with the p...
Wed Jan 15, 2020 7:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Water in Acid-Base Equilibria
Replies: 3
Views: 21

### Re: Water in Acid-Base Equilibria

Water is in such large excess and is the liquid solvent that it is not included in the ICE table at all as it does not effect Ka.
Wed Jan 15, 2020 7:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong acids/weak acids
Replies: 3
Views: 25

### Re: Strong acids/weak acids

All acids have a Ka value, but strong acids will have very large Ka values in comparison to weak acids as strong acids dissociate more.
Wed Jan 15, 2020 6:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: solubility
Replies: 3
Views: 32

### Re: solubility

If you have an equilibrium constant and initial concentrations, you can find the equilibrium concentrations using ICE tables and the quadratic equation. Knowing the equilibrium concentrations, you can see how much of the solute(reactants) dissociated or reacted to form the products.
Wed Jan 15, 2020 6:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka + Kb
Replies: 6
Views: 36

### Re: Ka + Kb

Kw = Ka x Kb, so Ka and Kb are inversely proportional meaning as one increases the other decreases. This makes sense when thinking about the relative values of Ka and Kb for the strength of acids and bases as a strong acid will have a very high Ka resulting in a low Kb because it is not very basic a...
Thu Jan 09, 2020 3:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units when Calculating Kp
Replies: 1
Views: 19

### Re: Units when Calculating Kp

K in any form is just a ratio and so the important thing with units is just to make sure all of the values of partial pressures are of the same type (bar, toor, etc.), which will keep the ratio the same as if you had used another unit to measure partial pressure.
Tue Jan 07, 2020 8:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: How to make ICE box
Replies: 17
Views: 158

### Re: How to make ICE box

If you are given the equilibrium concentration of a product, you can use stoichiometry to find the corresponding amounts of reactant used, and that becomes your change.
Tue Jan 07, 2020 8:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework Question 5G.9, Part B
Replies: 2
Views: 47

### Re: Homework Question 5G.9, Part B

Basically, part B is asking if everything but the amount of reactant in a container stays the same and more reactant is placed in a 1 L container, how will the partial pressure of the product, O2 change. For problems like these, it is asking how changing one piece of information can affect the resul...
Tue Jan 07, 2020 7:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 3
Views: 69

### Re: 5G.9

When calculating the equilibrium constant and reaction quotients, they can be calculated in terms of concentrations or partial pressures regardless of reactant and product phases. Calculating the ratios uses only gases and aqueous species, so it makes sense that when calculating the equilibrium cons...
Tue Jan 07, 2020 7:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: P(k) and P(q)
Replies: 2
Views: 37

### Re: P(k) and P(q)

When calculating K(p) and Q(p), solids and liquids(solvents) are not included but both aqueous species and gases are included.