Search found 52 matches

by Alice Ma 2K
Sun Mar 15, 2020 10:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode Mass
Replies: 10
Views: 108

Re: Electrode Mass

Changing the mass of the electrode won't change the cell potential. Changing the concentration of the solution would result in an increase in the cell potential.
by Alice Ma 2K
Sun Mar 15, 2020 10:35 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: isochoric
Replies: 4
Views: 108

Re: isochoric

Isochoric means to have constant volume while isometric means having the same dimensions.
by Alice Ma 2K
Sun Mar 15, 2020 10:34 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O
Replies: 8
Views: 76

Re: H2O

If H2O is in the gaseous form, it should be included. But if it's in the liquid or solid form, then it doesn't need to be included.
by Alice Ma 2K
Sun Mar 15, 2020 10:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic and Voltaic
Replies: 5
Views: 62

Re: Galvanic and Voltaic

They refer to the same type of cell. The three types of cells that we've covered are galvanic/voltaic, electrolytic, and concentration cells.
by Alice Ma 2K
Sun Mar 15, 2020 10:30 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reverse reaction rate?
Replies: 4
Views: 55

Re: Reverse reaction rate?

The reverse reaction rate can be found if you know the equilibrium constant and the forward reaction rate. The equilibrium constant is equal to the forward rate divided by the reverse rate.
by Alice Ma 2K
Sun Mar 15, 2020 10:28 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Glass Electrode
Replies: 5
Views: 54

Re: Glass Electrode

A glass electrode is an ion-selective electrode that is made to be sensitive to a specific type of ion. For example, a pH meter is a glass electrode that is made to detect H+.
by Alice Ma 2K
Mon Mar 09, 2020 1:55 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 7
Views: 33

Re: Cell diagram

If the reaction is aqueous on both sides, use commas to separate the species. You'll also need an inert metal (such as Platinum) to act as the conductor, which would go on the very left and right sides, separated from the aqueous species with single bars.
by Alice Ma 2K
Mon Mar 09, 2020 1:53 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: reaction rate vs average reaction rate
Replies: 5
Views: 30

Re: reaction rate vs average reaction rate

The instantaneous rate is over a very short period of time, whereas the average reaction rate is over the entirety of the reaction.
by Alice Ma 2K
Mon Mar 09, 2020 1:50 am
Forum: General Rate Laws
Topic: Enzyme saturation
Replies: 6
Views: 34

Re: Enzyme saturation

Once the enzyme becomes saturated, it is working at its optimal performance, so the reaction rate levels off.
by Alice Ma 2K
Mon Mar 09, 2020 1:49 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cell
Replies: 5
Views: 48

Re: Concentration Cell

A concentration cell has the same anode and cathode, but instead of the concentrations being at 1 M all the time, the concentration cell's anode and cathode will each have a different concentration. The difference in concentration allows there to be a charge gradient to make the cell work.
by Alice Ma 2K
Mon Mar 09, 2020 1:45 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Anode concentration
Replies: 3
Views: 21

Re: Anode concentration

The Nernst equation can be used to find the reaction quotient, which you can use to find the concentration of reactants or products. The anode will be the product.
by Alice Ma 2K
Thu Feb 27, 2020 1:14 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: nerst
Replies: 7
Views: 69

Re: nerst

Once you balance the redox reaction, you'll be able to determine how many moles of electrons are transferred, and that's the number you would use for n.
by Alice Ma 2K
Thu Feb 27, 2020 1:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: identifying strong reducing/oxidizing agents
Replies: 3
Views: 49

Re: identifying strong reducing/oxidizing agents

The larger the number in terms of magnitude, the stronger the agent would be.
by Alice Ma 2K
Thu Feb 27, 2020 1:06 pm
Forum: Balancing Redox Reactions
Topic: OH- in Basic Solutions
Replies: 6
Views: 40

Re: OH- in Basic Solutions

Start with adding H2O for balancing the oxygen, then add H+ to balance the hydrogens, and finally OH-.
by Alice Ma 2K
Thu Feb 27, 2020 12:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 29

Re: Cell Diagrams

Solid metal acts as the conductor, with the exception of liquid mercury which can also be a conductor.
by Alice Ma 2K
Thu Feb 27, 2020 12:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Hg and Cell Diagrams
Replies: 3
Views: 20

Re: Hg and Cell Diagrams

Liquid mercury has the property of being able to conduct electricity, so it doesn't need a solid metal conductor.
by Alice Ma 2K
Mon Feb 24, 2020 12:34 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Calculation of Eo of a cell
Replies: 3
Views: 57

Re: Calculation of Eo of a cell

One equation is adding the reduction potentials of the reactants and products together (making sure to flip the sign of the oxidized species), whereas the other method is to look specifically at the anode and the cathode and subtracting the cathode from the anode. The difference between the two is t...
by Alice Ma 2K
Mon Feb 24, 2020 12:28 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidation versus reduction
Replies: 9
Views: 65

Re: Oxidation versus reduction

The anode is always the one that is oxidized and the cathode is reduced, so if you know which species are oxidized or reduced, you can differentiate between the anode and the cathode. Would you know this by an equation given or the electron flow? Given a chemical equation, you can determine what sp...
by Alice Ma 2K
Mon Feb 24, 2020 12:26 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: conducting solids
Replies: 5
Views: 39

Re: conducting solids

Everything except metals and metalloids (some more than others) are nonconducting solids.
by Alice Ma 2K
Mon Feb 24, 2020 12:24 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell potential
Replies: 3
Views: 28

Re: cell potential

Standard cell potential is an intensive property, but it is still a chemical reaction that reaches equilibrium, which means it will be affected by a change in concentration or anything else in Le Chatelier's principle.
by Alice Ma 2K
Mon Feb 24, 2020 12:17 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electron Transfer
Replies: 3
Views: 25

Re: Electron Transfer

Electrons are transferred from one species to another, so there is no way of measuring the electrons lost or gained by a single species without a second one to accept or donate those electrons.
by Alice Ma 2K
Mon Feb 24, 2020 12:15 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidation versus reduction
Replies: 9
Views: 65

Re: Oxidation versus reduction

The anode is always the one that is oxidized and the cathode is reduced, so if you know which species are oxidized or reduced, you can differentiate between the anode and the cathode.
by Alice Ma 2K
Sun Feb 16, 2020 12:25 am
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 4
Views: 21

Re: Van't Hoff Equation

The temperature cancels out in the equation.
by Alice Ma 2K
Sun Feb 16, 2020 12:16 am
Forum: Van't Hoff Equation
Topic: T1 and T2
Replies: 7
Views: 46

Re: T1 and T2

K depends on T, so if one changes, so will the other.
by Alice Ma 2K
Sun Feb 16, 2020 12:12 am
Forum: Van't Hoff Equation
Topic: Enthalpy, Entropy, and Gibbs Free Energy
Replies: 7
Views: 51

Re: Enthalpy, Entropy, and Gibbs Free Energy

Temperature is not held constant in the Van't Hoff equation, so Gibbs free energy is not constant.
by Alice Ma 2K
Sun Feb 16, 2020 12:02 am
Forum: Balancing Redox Reactions
Topic: Acidic and basic redox reactions
Replies: 2
Views: 24

Re: Acidic and basic redox reactions

Knowing if the reaction takes place in an acidic, basic, or neutral environment dictates how you would balance the reaction.
by Alice Ma 2K
Sat Feb 15, 2020 11:54 pm
Forum: Balancing Redox Reactions
Topic: How do you combine half reactions?
Replies: 4
Views: 36

Re: How do you combine half reactions?

Yes, and the electrons in both equations would cancel out with each other so you'll just be left with the products and reactants.
by Alice Ma 2K
Sun Feb 09, 2020 12:38 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: degeneracy relation to thermo
Replies: 5
Views: 52

Re: degeneracy relation to thermo

Degeneracy is really only used in thermochemistry for calculating the entropy in the Boltzmann equation.
by Alice Ma 2K
Sun Feb 09, 2020 12:33 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: W
Replies: 4
Views: 33

Re: W

W refers to degeneracy, which is a statistical value for the number of different combinations for the arrangement of the molecules.
by Alice Ma 2K
Sun Feb 09, 2020 12:29 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Reactions at constant pressure
Replies: 2
Views: 22

Re: Reactions at constant pressure

For solids and liquids, the volume is difficult to change when the pressure is constant, also the number would be so small that it is negligible.
by Alice Ma 2K
Sun Feb 09, 2020 12:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: using ICE tables
Replies: 3
Views: 39

Re: using ICE tables

The numbers that you plug into the ICE table should be either molarity or pressure (for gases). Once you have molarity or pressure, you can calculate for the mass using the Ideal Gas Law and the molar mass of the molecule.
by Alice Ma 2K
Sun Feb 09, 2020 12:26 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: solids and liquids in the rxn quotient
Replies: 8
Views: 67

Re: solids and liquids in the rxn quotient

Yes, we always exclude solids and liquids when calculating for Q or K.
by Alice Ma 2K
Tue Jan 28, 2020 11:49 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Types of Systems
Replies: 3
Views: 33

Re: Types of Systems

Bomb calorimeters are isolated from the environment, creating a constant volume where nothing can go in or out of the system, which makes it an isolated system.
by Alice Ma 2K
Tue Jan 28, 2020 11:48 pm
Forum: Phase Changes & Related Calculations
Topic: Calorimeter
Replies: 5
Views: 38

Re: Calorimeter

A calorimeter measures the mass of liquid and the temperature change of the liquid to determine the quantity of energy gained or lost. It will usually have an inner and outer vessel to create an insulator and a thermometer and stirrer. The temperature change can be recorded and specific heat capacit...
by Alice Ma 2K
Tue Jan 28, 2020 11:41 pm
Forum: Phase Changes & Related Calculations
Topic: Calculating Work
Replies: 6
Views: 55

Re: Calculating Work

If work is done on a system, meaning that energy is going into the system to make something happen, it is positive. The opposite is negative. For example, is your system is gas in a piston, work being done on the system is when it is being compressed, so the work done is positive and the work done b...
by Alice Ma 2K
Tue Jan 28, 2020 11:39 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies
Replies: 4
Views: 38

Re: Enthalpies

The standard enthalpy of formation is the enthalpy change between the elements in their standard state (reactants) and the compounds (products). The standard enthalpy of reaction is the heat given off or taken up for the reaction, in other words, the enthalpy difference between the reactants and the...
by Alice Ma 2K
Mon Jan 27, 2020 10:32 pm
Forum: Phase Changes & Related Calculations
Topic: internal energy
Replies: 3
Views: 37

Re: internal energy

The change in internal energy, delta U, is calculated through Q plus W, where Q is the amount of heat transferred into the system and W is the work done on the system.
by Alice Ma 2K
Sat Jan 25, 2020 2:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Internal Energy of Systems
Replies: 2
Views: 30

Re: Internal Energy of Systems

Delta U refers to the change in the internal energy of a system, which is equal to the net heat transfer into the system Q, plus the net work done on the system, W.
by Alice Ma 2K
Sat Jan 25, 2020 2:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pressure and Enthalpy
Replies: 5
Views: 40

Re: Pressure and Enthalpy

Pressure and enthalpy have a directly proportional relationship with each other, so if one changes, the other will change in response.
by Alice Ma 2K
Sat Jan 25, 2020 2:27 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Irreversible Expansion
Replies: 4
Views: 42

Re: Irreversible Expansion

Irreversible expansion is gas expansion against constant external pressure. Also, it can be considered as an expansion that happens spontaneously without doing any work.
by Alice Ma 2K
Sat Jan 25, 2020 2:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure
Replies: 3
Views: 31

Re: Pressure

You could also determine the shift by calculating the reaction quotient given the new circumstances and compare that to the equilibrium constant.
by Alice Ma 2K
Sat Jan 25, 2020 2:17 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes
Replies: 7
Views: 35

Re: Phase changes

Phase changes are whenever the phase (solid, liquid, or gas) of a compound changes. The temperature stays constant during the change because the energy is being used to break the bonds that are holding that compound in that specific phase.
by Alice Ma 2K
Fri Jan 17, 2020 1:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Combing kA and kB
Replies: 2
Views: 27

Re: Combing kA and kB

Kw is equal to the concentration of H3O+ multiplied by the concentration of OH-. If you multiply Ka and Kb together, all species except for H3O+ and OH- would cancel out, giving you Kw.
by Alice Ma 2K
Fri Jan 17, 2020 1:12 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.3 PART B HELP
Replies: 4
Views: 96

Re: 6B.3 PART B HELP

For part B, the solution has been diluted due to the mistake made by the technician, so in order to solve for the pH, you would need to know the new concentration of the solution. To find that, you need to use the dilution equation: M1V1=M2V2.
by Alice Ma 2K
Thu Jan 16, 2020 11:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stability and K
Replies: 2
Views: 13

Re: Stability and K

Having a smaller K value indicates that the reactants are more stable than the products because a small K value means that the equation favors the reactants. The reverse is true if the K value is large, where the equation favors the products and the products are, therefore, more stable.
by Alice Ma 2K
Thu Jan 16, 2020 12:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.5 d
Replies: 3
Views: 30

Re: 5J.5 d

Other than the "short cut," you could solve for the equilibrium constant given the new conditions and compare it to the original. The comparison would tell you which way the equation would shift to, if at all.
by Alice Ma 2K
Thu Jan 16, 2020 12:19 pm
Forum: Ideal Gases
Topic: Kp given instead of Kc
Replies: 8
Views: 66

Re: Kp given instead of Kc

Given moles or grams, use the Ideal Gas law (PV=nRT) to pressure. Once converted, you can calculate using Kp.
by Alice Ma 2K
Sat Jan 11, 2020 5:42 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding inert gas [ENDORSED]
Replies: 9
Views: 83

Re: Adding inert gas [ENDORSED]

According to the book, the inert gas increases the total pressure within a reaction vessel. The reacting gases, however, will still occupy the same volume, meaning their concentrations and partial pressures remain the same despite the inert gas. Thus, the introduction of the inert gas has no effect...
by Alice Ma 2K
Thu Jan 09, 2020 6:00 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction quotient
Replies: 8
Views: 54

Re: Reaction quotient

K and Q can have different values because the concentrations used the calculate them are different even though the method to do so is the same. Because Q can be calculated at any point during the reaction, the concentrations won't be constant like they would if you were calculating K.
by Alice Ma 2K
Thu Jan 09, 2020 5:50 pm
Forum: Ideal Gases
Topic: converting Kc to Kp
Replies: 13
Views: 127

Re: converting Kc to Kp

If you know the molar concentration, you technically do know volume because molar concentration is mol per liter. For example, if there is 0.3 mol/L of a reactant, that means the volume is one liter. Hope that answered your question!
by Alice Ma 2K
Thu Jan 09, 2020 1:35 pm
Forum: Ideal Gases
Topic: Calculating K when there is multiple phases
Replies: 4
Views: 39

Re: Calculating K when there is multiple phases

You would have to convert the gaseous species into concentration using the Ideal Gas Law and find Kc. There is no way to find Kp because the aqueous species have no partial pressure.
by Alice Ma 2K
Thu Jan 09, 2020 12:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs K
Replies: 6
Views: 75

Re: Kc vs K

K or Kp is used when there are gases in the chemical equation, unless stated otherwise because gases can be discussed in terms of molar concentration. Meanwhile, Kc is for concentrations in mol/L for solutes in a condensed phase. Hi, I was wondering if you could explain why gases would be discussed...

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