Search found 67 matches

by Zenita Leang 2K
Sun Mar 17, 2019 5:51 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: delta h and q
Replies: 3
Views: 220

delta h and q

when is delta h equal to q?
by Zenita Leang 2K
Sun Mar 17, 2019 5:48 pm
Forum: Balancing Redox Reactions
Topic: redox in basic solutions
Replies: 1
Views: 81

redox in basic solutions

Can someone quickly summarize how to balance redox reactions in a basic solution?
by Zenita Leang 2K
Sun Mar 17, 2019 5:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: tripotic acid
Replies: 2
Views: 117

tripotic acid

what is a triprotic acid?
by Zenita Leang 2K
Sun Mar 10, 2019 4:25 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 1
Views: 36

Re: Arrhenius Equation

Yes, the Arrhenius Equation shows how a change in temperature affects rate of a reaction
by Zenita Leang 2K
Sun Mar 10, 2019 4:22 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 3
Views: 49

Re: Activation Energy

If activation energy increases, the reaction will be slower since more energy is needed in order for the reaction to occur and the reaction rate would be a larger value.
by Zenita Leang 2K
Sun Mar 10, 2019 4:21 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 6
Views: 71

Re: Catalysts

It makes the reaction go faster by decreasing the activation energy.
by Zenita Leang 2K
Sat Mar 02, 2019 12:53 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst
Replies: 4
Views: 66

Nernst

Where does the 0.0592 come from in the nernst equation?

E = E (standard) — (0.0592/n) log Q
by Zenita Leang 2K
Sat Mar 02, 2019 12:43 pm
Forum: General Rate Laws
Topic: Rate Law
Replies: 1
Views: 29

Re: Rate Law

The experiments are necessary because they are the means by which we can compare concentrations and equilibrium constants in order to determine the rate law.
by Zenita Leang 2K
Fri Mar 01, 2019 11:29 am
Forum: Balancing Redox Reactions
Topic: Strength of reducing agent
Replies: 10
Views: 187

Re: Strength of reducing agent

If something is more negative, then it has more reducing power. To have more reducing power means it can gain more electrons. When E cell is more negative, this means that the reducing power is very high and and it can be easily oxidized.
by Zenita Leang 2K
Sun Feb 24, 2019 2:57 pm
Forum: Balancing Redox Reactions
Topic: How do you balance a redox reaction
Replies: 4
Views: 79

Re: How do you balance a redox reaction

balance the moles of a reaction first and then on the side that is most positive, count to see how many electrons to balance the charge.
by Zenita Leang 2K
Sun Feb 24, 2019 2:52 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: gibbs free energy
Replies: 5
Views: 73

gibbs free energy

what does gibbs free energy tells about a reaction?
by Zenita Leang 2K
Sun Feb 24, 2019 2:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 3
Views: 45

salt bridge

why is a salt bridge needed in a galvanic cell?
by Zenita Leang 2K
Wed Feb 13, 2019 1:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: using gas constant R
Replies: 4
Views: 80

Re: using gas constant R

You use 3/2R for Cv, when volume is constant in a reaction. This is seen in deltaS=nClnT2/T1. You use 5/2R for Cp when pressure is constant in a reaction, this could be used in the same equation.
by Zenita Leang 2K
Wed Feb 13, 2019 1:06 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Delta S equations
Replies: 3
Views: 96

Re: Delta S equations

If you have a constant volume then you will use Cv which is equivalent to R. If it has a constant pressure, then you will use Cp which is equivalent to R. R is the constant on the constants and equations sheet.
by Zenita Leang 2K
Sat Feb 09, 2019 5:43 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: deltaS=nCvln(t2/t1) what is Cv?
Replies: 7
Views: 117

Re: deltaS=nCvln(t2/t1) what is Cv?

Cv is constant volume, which is times the constant R. You use this in deltaS=nCvln(t2/t1) instead of deltaS=nRln(V2/v1) when you have a monatomic ideal gas at constant volume to calculate for entropy.
by Zenita Leang 2K
Sat Feb 09, 2019 5:25 pm
Forum: Calculating Work of Expansion
Topic: Derivations - Midterm
Replies: 3
Views: 55

Re: Derivations - Midterm

The derivations are helpful in understanding I think, but we should just know how to use them and under what conditions each one can be used for the midterm.
by Zenita Leang 2K
Sat Feb 09, 2019 4:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Closed, Open, and Isolated Systems
Replies: 5
Views: 73

Re: Closed, Open, and Isolated Systems

An open system is where matter and energy of a system can interact with the surroundings, so for example, an open beaker. A closed system is where energy, but not matter, of a system can interact with the surroundings. In this case, this would be like a frozen bottle of water, where the matter stays...
by Zenita Leang 2K
Sat Feb 09, 2019 4:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta H's
Replies: 1
Views: 39

Re: Delta H's

ΔHf^o is the enthalpy formation under standard conditions (so 1 atm, 1 mol, and and 278 K) whereas ΔHf just refers to enthalpy formation. ΔHf^o is otherwise known as standard reaction enthalpy for a substance.
by Zenita Leang 2K
Sun Feb 03, 2019 1:03 pm
Forum: Phase Changes & Related Calculations
Topic: State Function
Replies: 10
Views: 102

State Function

I still don't really have a clear understanding of what a state function is. Can someone define it and explain why work is not a state function?
by Zenita Leang 2K
Sun Feb 03, 2019 12:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat (Csp)
Replies: 3
Views: 60

Re: Specific Heat (Csp)

Otherwise, it is mostly usually given.
by Zenita Leang 2K
Sun Feb 03, 2019 12:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.113a 6th edition
Replies: 2
Views: 44

Re: 8.113a 6th edition

Only CO and H2O is used since Carbon (C) in the equation is in a solid phase and the gaseous H2 would have an enthalpy of 0 since it is a diatomic molecule.
by Zenita Leang 2K
Sun Feb 03, 2019 12:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Heat VS. Energy
Replies: 5
Views: 95

Re: Heat VS. Energy

The textbook defines heat as the energy that is transferred as a result of temperature differences, whereas enthalpy refers to heat transfer. Energy itself is the capacity of a system to do work.
by Zenita Leang 2K
Sun Jan 27, 2019 5:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of Formation
Replies: 2
Views: 42

Re: Standard Enthalpy of Formation

I believe it is based off of the difference in heat of the enthalpy of the reactants subtracted from the enthalpy of the products at standard reaction enthalpy
by Zenita Leang 2K
Sun Jan 27, 2019 4:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity & enthalpy
Replies: 1
Views: 38

Heat capacity & enthalpy

Is heat capacity the same thing as enthalpy? If not, what is the difference?
by Zenita Leang 2K
Sun Jan 27, 2019 4:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Solving for a reaction's enthalpy
Replies: 2
Views: 40

Solving for a reaction's enthalpy

In lecture, we were shown the three different ways to solve for enthalpy (Hess' Law, bond enthalpies, and standard enthalpy). Can these 3 methods be used interchangeably to solve or is one method preferable to the other?
by Zenita Leang 2K
Thu Jan 17, 2019 1:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Percent Ionization
Replies: 3
Views: 48

Percent Ionization

If percent ionization is more than 5% (and we were not able to approximate and determine the "x" in change in molarity as insignificant), what would we have to do to figure out K?
by Zenita Leang 2K
Thu Jan 17, 2019 1:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conjugates
Replies: 4
Views: 64

Conjugates

How can you determine the conjugate acid of a strong base and the conjugate base of a strong acid in a reaction?
by Zenita Leang 2K
Thu Jan 17, 2019 12:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 1
Views: 42

Autoprotolysis

What exactly is autoprotolysis? Does it refer to one specific reaction or does it describe a different type of reaction?
by Zenita Leang 2K
Sat Jan 12, 2019 2:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibria Changes
Replies: 3
Views: 46

Re: Equilibria Changes

Changing the concentration of reactants or products will change the reaction quotient, the Q, of a reaction. The K doesn't change because there is a specific equilibrium constant, K, for each reaction at given temperatures. When you change the concentration of a reaction or a product, the reaction w...
by Zenita Leang 2K
Sat Jan 12, 2019 2:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: partial pressures vs concentrations
Replies: 4
Views: 49

Re: partial pressures vs concentrations

You can look at the units that are given in the problem! If they give you mol/L (molarity) then you will use concentration to find K but if they give you torr, atmospheres (atm), or bar, then you will use partial pressure.
by Zenita Leang 2K
Sat Jan 12, 2019 1:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Table
Replies: 6
Views: 111

Re: ICE Table

You can use ICE tables for concentrations but you can also fill ICE tables with values of partial pressure.
by Zenita Leang 2K
Sat Dec 08, 2018 7:09 pm
Forum: Limiting Reactant Calculations
Topic: limiting reagents
Replies: 1
Views: 136

Re: limiting reagents

The limiting reagent is both. If a reactant runs out first, then the amount of product produced is limited to however much reactant there is, Therefore, the limiting reagent is the reactant that runs out first and would thus dictate how much product could be produced.
by Zenita Leang 2K
Sat Dec 08, 2018 7:08 pm
Forum: Dipole Moments
Topic: Strengths if Intermolecular Forces
Replies: 1
Views: 130

Re: Strengths if Intermolecular Forces

From least strongest to strongest, the order goes:
1. induced dipole-induced dipole (LDF/vanderwaals)
2. induced dipole-dipole
3. dipole-dipole
4. H-bonds
by Zenita Leang 2K
Sat Dec 08, 2018 7:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX4E2
Replies: 1
Views: 95

Re: AX4E2

Lone pairs don't affect in this orientation so it would be non polar.
by Zenita Leang 2K
Sat Dec 08, 2018 7:01 pm
Forum: Limiting Reactant Calculations
Topic: mass percentage
Replies: 1
Views: 122

Re: mass percentage

Take the mass of the element you are looking for divided by the mass of the total molecule times a hundred and this is how you get the mass percentage.
by Zenita Leang 2K
Sat Dec 08, 2018 5:50 pm
Forum: Calculating the pH of Salt Solutions
Topic: Ph to salt solution
Replies: 2
Views: 115

Re: Ph to salt solution

Yes but we don't need to know how to do that
by Zenita Leang 2K
Sat Dec 08, 2018 5:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining the Coordination number
Replies: 3
Views: 40

Re: Determining the Coordination number

Coordination number is how many bonds there are on a transition metal. Transition metals don't have more than a single bond attached.
by Zenita Leang 2K
Sat Dec 08, 2018 5:42 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Final Exam
Replies: 8
Views: 678

Re: Final Exam

I believe equilibrium is for chem 14b so calculating equilibrium shouldn't be on the final!
by Zenita Leang 2K
Sat Dec 08, 2018 5:40 pm
Forum: Lewis Acids & Bases
Topic: Acids & Bases we need to memorize
Replies: 1
Views: 39

Re: Acids & Bases we need to memorize

The strong acids are HCl, HI, HBr, HNO3, HClO4, H2SO4, HClO3. The strong bases we should know are the Group 1 hydroxides (NaOH, LiOH, KOH), alkali earth metal hydroxides, and Group 1 and 2 oxides.
by Zenita Leang 2K
Sat Dec 08, 2018 5:29 pm
Forum: Dipole Moments
Topic: Dipole Moments signifying polarity
Replies: 2
Views: 151

Re: Dipole Moments signifying polarity

To be considered "polar," you don't necessarily have to look at the strength of the dipole. Determining polarity can also be determined on direction/orientation and whether the dipole moments cancel each other out or not.
by Zenita Leang 2K
Sat Dec 08, 2018 1:02 am
Forum: Calculating the pH of Salt Solutions
Topic: Atoms that don't affect pH
Replies: 3
Views: 154

Re: Atoms that don't affect pH

Br does not contribute to the production of OH- or H2O so that is why it is not included in the equation. NH4 on the other hand can donate its H+ so it acts as an acid.
by Zenita Leang 2K
Sat Dec 08, 2018 12:57 am
Forum: Amphoteric Compounds
Topic: Amphiprotic vs. Amphoteric
Replies: 7
Views: 198

Re: Amphiprotic vs. Amphoteric

Amphiprotic is a compound that can both donate or accept a hydrogen ion (aka a proton). Amphoteric means a compound can act as either an acid or a base. Amphiprotic refers specifically to its ability to accept and donate protons whereas amphoteric refers to whether a compound can or cannot react wit...
by Zenita Leang 2K
Sat Dec 08, 2018 12:46 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelate geometry
Replies: 2
Views: 52

Re: Chelate geometry

A chelate compound's structure would depend on how many ligands there are
by Zenita Leang 2K
Sat Dec 08, 2018 12:43 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Angles
Replies: 2
Views: 59

Re: Angles

I think your theory is correct, also since Fluorine is more electronegative and so it repels the Hydrogen and would alter the bond angles.
by Zenita Leang 2K
Sat Dec 08, 2018 12:37 am
Forum: Naming
Topic: churro 30
Replies: 1
Views: 37

Re: churro 30

I think the formula would be [Cr(NH3)3(H2O)3)]Cl3
by Zenita Leang 2K
Sat Dec 08, 2018 12:30 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: HOCl vs HOI
Replies: 9
Views: 261

HOCl vs HOI

Why is HOCl a stronger acid than HOI?
by Zenita Leang 2K
Sat Dec 08, 2018 12:25 am
Forum: Naming
Topic: churro 29
Replies: 1
Views: 40

Re: churro 28

This is called trichlorooxalatochromate.
by Zenita Leang 2K
Sat Dec 08, 2018 12:18 am
Forum: Naming
Topic: Bis, Tris, Tetrakis, etc.
Replies: 3
Views: 76

Re: Bis, Tris, Tetrakis, etc.

You use bis-tris-tetrakis for polydentate complexes. This is in comparison to bi- tri- and tetra- which is used for monodentate.
by Zenita Leang 2K
Sat Dec 08, 2018 12:15 am
Forum: Naming
Topic: churro 27
Replies: 2
Views: 52

Re: churro 27

The name of this compound is potassium tetracyanonickelate (II)!
by Zenita Leang 2K
Sat Dec 08, 2018 12:00 am
Forum: Naming
Topic: Naming (churro)
Replies: 3
Views: 82

Naming (churro)

Can someone explain why chlorine is labeled as "chloro" in this compound? [Co(NH2CH2CH2NH2)2(CN)(Cl)]Cl
Also why is ethylenediamine labeled as "bis"?
by Zenita Leang 2K
Fri Dec 07, 2018 11:43 pm
Forum: Biological Examples
Topic: Cisplatin
Replies: 3
Views: 128

Cisplatin

Hello.

Why is cisplatin used in chemotherapy?

Many thanks.

:)
by Zenita Leang 2K
Fri Dec 07, 2018 10:31 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordinate covalent bond
Replies: 1
Views: 45

Re: Coordinate covalent bond

A coordinate covalent bond has bonds with a complex ion whereas a covalent bond is just simple ions being bonded.
by Zenita Leang 2K
Fri Dec 07, 2018 12:03 am
Forum: Electronegativity
Topic: Electronegativity vs ionization energy
Replies: 5
Views: 180

Re: Electronegativity vs ionization energy

Electronegativity is how strongly electrons are attracted to an atom. Ionization energy is the energy required to remove an electron from an atom.
by Zenita Leang 2K
Sun Dec 02, 2018 11:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX3E
Replies: 18
Views: 273

Re: AX3E

The molecule with an AX3E shape have a trigonal pyramidal shape.
by Zenita Leang 2K
Sun Dec 02, 2018 11:56 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: what is a ligand?
Replies: 8
Views: 148

Re: what is a ligand?

A ligand is a molecule that can bind to another molecule. The ligand donates since it is an acid donor.
by Zenita Leang 2K
Sun Dec 02, 2018 11:53 pm
Forum: Bronsted Acids & Bases
Topic: Net Ionic Equations
Replies: 2
Views: 63

Re: Net Ionic Equations

For metals and nonmetals (in Group 1, Group 2, and Groups 13-18), you can determine an ion's charge by looking at the valence electrons in the s and p group. Calcium for example would be a +2 charge. Sulfur would have a -2 charge because it has 6 valence electrons and needs two more to complete its ...
by Zenita Leang 2K
Sun Nov 25, 2018 2:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Planar or Trigonal Pyramidal?
Replies: 4
Views: 81

Re: Trigonal Planar or Trigonal Pyramidal?

Its molecular shape is trigonal pyramidal since it has a lone pair! Lone pairs will throw the electron shape off a little and thus SO32- has a bond angle of 109.5.
by Zenita Leang 2K
Sun Nov 25, 2018 2:33 pm
Forum: Hybridization
Topic: BrF3
Replies: 2
Views: 57

BrF3

Why does BrF3 have a hybridization of sp3d?
by Zenita Leang 2K
Sun Nov 25, 2018 2:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipoles
Replies: 2
Views: 52

Dipoles

What is a dipole and how are they determined?
by Zenita Leang 2K
Sun Nov 18, 2018 11:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VESPR Theory
Replies: 3
Views: 96

Re: VESPR Theory

We can use the VESPR theory to predict shapes by looking at the amount of electrons of an atom and understanding how the electrons will arrange themselves in a geometric shape since electrons will repel each other. Different amounts of electrons and bond angles will have different shapes.
by Zenita Leang 2K
Sun Nov 18, 2018 11:41 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 2
Views: 56

Re: sigma and pi bonds

Sigma bonds allow bound atoms to rotate, meaning the electron density has cylindrical symmetry around the axis. Pi bonds do not allow bound atoms to rotate and thus the electron density is on each side of the internuclear axis. Sigma bonds also interact from one bond to the other while pi bonds over...
by Zenita Leang 2K
Sun Nov 18, 2018 11:32 pm
Forum: Ionic & Covalent Bonds
Topic: Intra vs Intermolecular forces
Replies: 9
Views: 466

Re: Intra vs Intermolecular forces

Intermolecular forces are easier to break since they are weaker.
by Zenita Leang 2K
Sun Nov 11, 2018 11:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 3
Views: 62

Re: VSEPR

A lone pair in the central atom
by Zenita Leang 2K
Sun Nov 11, 2018 11:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 3
Views: 63

Re: VSEPR

Yes, to double check you can look for any lone pairs in the model and see if there is any repulsion with any of the other bond angles.
by Zenita Leang 2K
Sun Nov 11, 2018 11:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 4
Views: 55

Re: Bond Angles

Tetrahedral shaped atoms have bonds at a 109.5 degree angle because of its 3 dimensional shape! If each bond was 90 degrees away from each other, it would be more similar to having a flat shape but to maximize the space that the atom has (and because of the negatively charged electron's repulsion fr...
by Zenita Leang 2K
Tue Nov 06, 2018 10:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configuration of Niobium
Replies: 2
Views: 83

electron configuration of Niobium

what is the electron configuration of Niobium?
by Zenita Leang 2K
Wed Oct 24, 2018 6:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 7
Views: 156

Rydberg Equation

Yeah, he said not to use the Rydberg equation but we can use the E= -hr/n^2 instead! :)

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