Search found 31 matches

by Amar Singh
Sat Mar 16, 2019 11:33 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Flow of electrons
Replies: 2
Views: 21

Re: Flow of electrons

One way to think of it is that cathode is +, so electrons are being added to it.

The anode is -. so electrons are being removed from it.

The electron from will go from the site being removed (anode) to the site where the electrons are added (cathode).
by Amar Singh
Sat Mar 16, 2019 11:32 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Corrosion
Replies: 2
Views: 19

Re: Corrosion

You don't need to know the exact processes, just need to be able to understand them if presented to you.
by Amar Singh
Sat Mar 09, 2019 2:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic and Endothermic Reactions
Replies: 4
Views: 50

Re: Exothermic and Endothermic Reactions

If the temperature is increased, the reaction wants to balance out the change of the added energy, so the endothermic process will be favored. If the temperature is decreased, the reaction wants to add energy to balance out its environment so the exothermic process is favored.
by Amar Singh
Sat Mar 09, 2019 2:54 pm
Forum: Ideal Gases
Topic: sre
Replies: 5
Views: 57

Re: sre

You can just think of it as the normal enthaply, except when the conditions of the reactants and products are in the standard state. So it must be in 1 bar and pure states of elements.
by Amar Singh
Sat Mar 09, 2019 2:51 pm
Forum: Ideal Gases
Topic: ICE Table Values
Replies: 9
Views: 90

Re: ICE Table Values

ICE tables can be used to calculate how much a weak acid or base has reacted. It can use moles, molarity, or partial pressure values. Make sure everything is consistent.
by Amar Singh
Sun Mar 03, 2019 5:44 pm
Forum: Balancing Redox Reactions
Topic: balancing redox reactions
Replies: 5
Views: 41

Re: balancing redox reactions

For balancing O, you will always use H2O. For balancing H+, if its acidic, you add H+. If it is a basic solution, you add H2O to the side needing the H+, and add OH- to the other side to balance it out.
by Amar Singh
Sun Mar 03, 2019 5:43 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number?
Replies: 12
Views: 66

Re: Oxidation number?

Group 1 elements have +1. Group 2 elements have +2. Group 17 have -1. Group 16 have -2. The others can vary a bit depending on the element and its state.
by Amar Singh
Sun Mar 03, 2019 5:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt(s)
Replies: 10
Views: 72

Re: Pt(s)

A solid state conductor is necessary for the cells. When there isn't a solid given, Pt(s) is typically used and thus you must include it in the cell diagram.
by Amar Singh
Sat Feb 23, 2019 3:38 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy and mass
Replies: 2
Views: 31

Re: Entropy and mass

The more massive a molecule, the more atoms it will typically have and the more states it can be in, resulting in more entropy.
by Amar Singh
Sat Feb 23, 2019 3:37 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Constants abs Equations Worksheet
Replies: 2
Views: 34

Re: Constants abs Equations Worksheet

The equation sheet posted online is the one that will be used for the rest of the tests.
by Amar Singh
Sat Feb 23, 2019 3:36 pm
Forum: Calculating Work of Expansion
Topic: Nonexpansion work vs expansion work
Replies: 3
Views: 32

Re: Nonexpansion work vs expansion work

The simplest way to think about it that expansion work involves volume (something is being expanded) and nonexpansion work is all other types of work
by Amar Singh
Sun Feb 17, 2019 11:52 pm
Forum: Phase Changes & Related Calculations
Topic: rotational v vibrational energy
Replies: 5
Views: 56

Re: rotational v vibrational energy

At room temperature, vibrational energy is negligible. It is the energy of the atoms vibrating in the bonds. Rotational energy is more like the molecule rotating around an axis.
by Amar Singh
Sun Feb 17, 2019 11:48 pm
Forum: Phase Changes & Related Calculations
Topic: Isothermal
Replies: 9
Views: 83

Re: Isothermal

Typically the tests will say isothermal, or temperature constant. Unless explicitly stated, you can assume it is isothermal.
by Amar Singh
Sun Feb 17, 2019 11:48 pm
Forum: Phase Changes & Related Calculations
Topic: Slope of heating curve
Replies: 8
Views: 87

Re: Slope of heating curve

If a substance has a lower heat capacity, that means it will take less energy (x) to make an increase in the temperature (y). This results in a steep slope. Conversely, if a substance has a higher heat capacity, it takes more energy (x) to increase the temperature so it will have a smaller slope.
by Amar Singh
Sun Feb 10, 2019 4:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Units
Replies: 6
Views: 52

Re: Units

There aren't units since they cancel out. Kc will be in brackets, Kp will be in parenthesis, but at the end of the day you only use numbers without anything on them.
by Amar Singh
Sun Feb 10, 2019 4:36 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K constant
Replies: 5
Views: 174

Re: K constant

Brackets is for concentration (Kc) whereas the P is for the partial pressure (Kp)
by Amar Singh
Sun Feb 10, 2019 4:35 pm
Forum: Ideal Gases
Topic: derivatives and integrals
Replies: 6
Views: 57

Re: derivatives and integrals

The integral is used to find the work. It's probably best to use the other equation he taught us, the integral was more for deriving the equation.
by Amar Singh
Sun Feb 03, 2019 2:35 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: When to use Quadratic equation
Replies: 10
Views: 87

Re: When to use Quadratic equation

Typically if the problem involves x^2 and Kc < 10^-3, you must use the quadratic equation to solve.
by Amar Singh
Sun Feb 03, 2019 2:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What do do when moles are given
Replies: 5
Views: 53

Re: What do do when moles are given

When moles are given you typically use the volume to find the molar concentration, or use it to find the Q value.
by Amar Singh
Sun Feb 03, 2019 2:32 pm
Forum: Ideal Gases
Topic: atm vs. bar?
Replies: 23
Views: 275

Re: atm vs. bar?

Practically you can usually use both but you should definitely use whichever one is specified in the problem.
by Amar Singh
Sun Jan 27, 2019 3:11 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Finding Concentrations of H3O+ and OH-
Replies: 2
Views: 59

Re: Finding Concentrations of H3O+ and OH-

As Ibrahim said, [H3O+] is not included in the equation, so we cannot use mole ratios directly to find its concentration. A big mistake that some might do is create some incorrect equation to account for [H3O+] to try and directly solve for it with the initial concentration. We use Kw to solve it be...
by Amar Singh
Sun Jan 27, 2019 3:03 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure caused by Volume
Replies: 3
Views: 52

Re: Change in Pressure caused by Volume

Yes, remember that Le Chatelier's principle wants equations to balance out any changes that might occur in the environment. This means that when pressure is increased, the side with the less amount of moles will be favored to try and balance it out. For example, if the products have the smaller amou...
by Amar Singh
Sun Jan 27, 2019 2:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE problems
Replies: 5
Views: 62

Re: ICE problems

Usually you will know in the problem which way the reaction is proceeding. Most of the times it will be the forward reaction that is favored, but occasionally it will be the reverse reaction. Sometimes the concentrations of the products and reactants are given, so you might have to calculate Q and u...
by Amar Singh
Sun Jan 20, 2019 3:26 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: How to tell if a chemical is an acid or base?
Replies: 4
Views: 55

Re: How to tell if a chemical is an acid or base?

First of all you need to define the type of acid/base you want to check. There are 3 main types: arrhenius, bronsted-lowry, and lewis. ARRHENIUS ACIDS will donate a H+ ion when dissolved in water ARRHENIUS BASES will donate a OH- ion when dissolved in water BRONSTED-LOWRY ACIDS will donate a H+ ion ...
by Amar Singh
Sun Jan 20, 2019 3:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pKa vs pH?
Replies: 3
Views: 59

Re: pKa vs pH?

The simple way to look at is the Ka is the equilibrum concentration and if you take the -log of it, you get the pH. Same for pKb/pOH. To convert it make, simply take the 10^-(pH/pOH) to find the pKa/pKb
by Amar Singh
Sun Jan 20, 2019 3:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Given Kw
Replies: 2
Views: 20

Re: Given Kw

The concentrations of [H3O+] and [OH-] are equal because for water at any temperature, the only molecule you are starting off with is [H2O]. If one of the hydrogens from [H2O] leaves the original molecule and joins another [H2O] molecule, the new molecule becomes [H3O+] and the old one becomes [OH-]...
by Amar Singh
Sat Jan 12, 2019 9:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE table and cubic expressions
Replies: 1
Views: 21

Re: ICE table and cubic expressions

As far as I can tell, Professor Lavelle will not give us any problems with cubic roots to solve on ICE tables. The syllabus only implies that we will be doing problems that only need the quadratic formula to solve. In other scenarios outside the class, the best way to solve more complex chemical equ...
by Amar Singh
Sat Jan 12, 2019 9:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solving for K
Replies: 7
Views: 59

Re: Solving for K

A simple rule of thumb would be that if the equation involves gases, you use the parenthesis to denote partial pressure, and when the equation involves an aqueous solution, you use the brackets to denote molar concentration. There are exceptions to this rule (particularly the one with gases, as some...
by Amar Singh
Sat Jan 12, 2019 9:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 3
Views: 23

Re: ICE Tables

So you probably already know that the "c" value stands for "change in equilibrium". In most problems, you typically use -x for the reactants, and +x for the products. This gives you an equation for the "e" part of the ICE table, which you can then use the K value to sol...
by Amar Singh
Sat Jan 12, 2019 9:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 4
Views: 30

Re: Kc and Kp

Kc is the equilibrium constant for molar concentrations. This is typically used with aqueous solutions, however there are certain times that you would use them with gases (not things you have to worry about right now). Kp is what you should be using to denote the equilibrium constant for gases with ...

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