Search found 29 matches

by Anuk Burli 2C
Sat Mar 14, 2015 10:29 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Showing hydrogens in chair structure
Replies: 1
Views: 370

Showing hydrogens in chair structure

Hi When drawing a chair structure especially for a ring flip is it necessary to draw in all the hydrogens?
by Anuk Burli 2C
Sat Mar 14, 2015 2:46 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Newman projection rotation 2014 7E
Replies: 1
Views: 1260

Newman projection rotation 2014 7E

Hi 7E on 2014 asks to draw the most stable Newman projection for 3-chloro-4,4,4- trihydroxy-3-methylbutanenitrile. The answer key says that the C(OH)3 has to be gauche to both hydrogens but I drew this. Why is this incorrect?
by Anuk Burli 2C
Thu Mar 05, 2015 11:35 pm
Forum: *Alkenes
Topic: Double bond placement 1.11
Replies: 1
Views: 929

Double bond placement 1.11

When you draw the line structure for propene does it matter where you put the double bond? Is there a specific reason the answer key put the double bond between the second and the third carbon?
by Anuk Burli 2C
Sun Feb 22, 2015 2:58 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Questions about 14.85
Replies: 4
Views: 869

Re: Questions about 14.85

I'm not sure about part a but for part b I believe that inert noble gases don't affect the rate of the reaction so they wouldn't be included. I don't think you ever add noble gases because they're inert similar to how they didnt affect equilibrium
by Anuk Burli 2C
Thu Feb 05, 2015 5:31 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: General Confusion on Homework Problem #13.103
Replies: 2
Views: 554

Re: General Confusion on Homework Problem #13.103

we would use the method of half reactions to solve this problem so our two half reactions would be F2 +2e- = 2F- which has a value of 2.87 V and F2+2H+ + 2e= 2HF which has a value of 3.03 V HF is a weak acid so does not dissociate completely so it dissociates into HF=H+ +F- so the Ka for this reacti...
by Anuk Burli 2C
Sat Jan 31, 2015 4:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for calculating standard reaction enthalpies...
Replies: 2
Views: 481

Re: Units for calculating standard reaction enthalpies...

I know Hess's Law is generally given in kJ, bond enthalpies tend to be given in kj/mol, I think Gibb's free energy is given in KJ in a hess's law type of calculation, standard reaction enthalpies in kj/mol, standard reaction entropies in j/mol.
by Anuk Burli 2C
Sun Jan 25, 2015 9:51 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal expansion
Replies: 2
Views: 490

Isothermal expansion

Are isothermal processes always reversible? If the question doesn't specify if the process is reversible but it says it's isothermal do we assume that it's reversible?
by Anuk Burli 2C
Sun Jan 25, 2015 9:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW 7.45 Question
Replies: 3
Views: 395

Re: HW 7.45 Question

Hi

So PV=nRT and density = mass over volume and n=mass (m)/ molar mass (M) so PV=m/M (RT) so divide both sides by RT and then divide both sides by V so you get P/RT=m/M *V and m/v is density so you get P/RT=D/M so multiply both sides by M to get MP/RT = Density
by Anuk Burli 2C
Sun Jan 25, 2015 7:57 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Problem 7.53
Replies: 1
Views: 444

Re: Homework Problem 7.53

Hi

They're not saying the specific heat is negative they're using q system + q surroundings =0 so q system= - q surroundings so they just distributed the negative sign in q surroundings to the specific heat of water.
by Anuk Burli 2C
Sat Jan 24, 2015 2:09 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: units for enthalpy of reaciton
Replies: 1
Views: 261

Re: units for enthalpy of reaciton

Hi,

I think the units should be kj/mol for standard enthalpy of reaction. However, in calorimetry problems where it is not asking for standard enthalpy of reaction the unit can just be kj.
by Anuk Burli 2C
Sat Jan 24, 2015 2:06 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: The sign in calculation of dG using dH,T & dS (Qz1,w2013,#6)
Replies: 1
Views: 268

Re: The sign in calculation of dG using dH,T & dS (Qz1,w2013

Hi,

I think it's just a typo because if you leave entropy and enthalpy both as negative and plug it in you get the same answer of 55.40 kj/mol
by Anuk Burli 2C
Sat Jan 24, 2015 2:01 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Ch.7 Question 51
Replies: 2
Views: 309

Re: Ch.7 Question 51

Hi

Yah I think if they don't give you temperature assume it to be 25 degrees C or 298 K
by Anuk Burli 2C
Thu Jan 22, 2015 1:22 am
Forum: Phase Changes & Related Calculations
Topic: What is Delta E?
Replies: 3
Views: 4382

Re: What is Delta E?

correct me if I'm wrong but I'm pretty sure Delta E has the same formulas as delta U which is q+w
by Anuk Burli 2C
Sun Jan 18, 2015 4:06 pm
Forum: Phase Changes & Related Calculations
Topic: Homework Problem #19
Replies: 5
Views: 797

Re: Homework Problem #19

The way to remember any problem like these kind of calorimeter problems is to think of it in terms of the first law of thermodynamics where any heat released by the system has to be absorbed by the surroundings or aka q system + q surroundings=0. As long as you correctly identify the system and the ...
by Anuk Burli 2C
Mon Jan 12, 2015 12:13 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Contribution to the heat capacity by molecular motions
Replies: 3
Views: 820

Re: Contribution to the heat capacity by molecular motions

Hi I believe that the larger the molecule for similar types of bonding such as HCN and HBR the larger the molecule the higher the heat capacity. You also have to take into account that certain equations can predict heat capacities. For example Cp for monatomics is 5/2 R where R is the ideal gas cons...
by Anuk Burli 2C
Sat Jan 10, 2015 8:14 pm
Forum: Phase Changes & Related Calculations
Topic: State/Path Functions
Replies: 3
Views: 3629

Re: State/Path Functions

also an important implication of state functions is that according to hess's law a series of reactions of state functions can be summed up to generate a new value for the overall reaction. Examples of these state functions would be enthalpy, entropy, and Gibb's free energy (H, S, and G). However, yo...
by Anuk Burli 2C
Wed Dec 10, 2014 11:24 pm
Forum: Bronsted Acids & Bases
Topic: Net ionic equations
Replies: 1
Views: 253

Re: Net ionic equations

Hi Net Ionic equations are where you remove spectator ions in a reaction or the ions that are exactly the same on both sides of the reaction aka they were present in the reaction but did not actually participate in the reaction. To write a net ionic equation: Write the balanced molecular equation, t...
by Anuk Burli 2C
Tue Dec 09, 2014 12:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Graph of a Concentration
Replies: 2
Views: 425

Re: Graph of a Concentration

Hi,

The graph would look like a plateau as in the concentration of the products (aka K+) would start at 0 and then rise and level off at the middle of the graph.


Anuk Burli
by Anuk Burli 2C
Tue Dec 09, 2014 12:06 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Solevants other than water
Replies: 1
Views: 282

Re: Solevants other than water

Hi

I'm not sure if they will be on the final but some other solvents could be methanol, isopropanol, benzene.


Anuk Burli
by Anuk Burli 2C
Mon Dec 08, 2014 12:24 am
Forum: Lewis Acids & Bases
Topic: Quick explanation of determining whether an acid or base?
Replies: 4
Views: 1166

Re: Quick explanation of determining whether an acid or base

Hi!

I believe that that's correct where Arrhenius and Bronsted is a reaction with water but I believe that lewis acids and bases don't necessarily have to be in water. For example PF5 +F- = Pf6 is a lewis acid-base reaction.
by Anuk Burli 2C
Sun Dec 07, 2014 10:47 pm
Forum: Lewis Acids & Bases
Topic: Quick explanation of determining whether an acid or base?
Replies: 4
Views: 1166

Re: Quick explanation of determining whether an acid or base

Hi There are 3 definitions of acids and bases. Arrhenius, Bronsted Lowry, and Lewis. If you draw the lewis structure and it can accept an electron then it is a lewis acid but if it can donate an electron it is a lewis base. If it is a Bronsted-Lowry acid it is a proton donor and if it is a base it i...
by Anuk Burli 2C
Mon Dec 01, 2014 10:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: #6 Quiz 3 WKBK Prep
Replies: 2
Views: 425

Re: #6 Quiz 3 WKBK Prep

Hi. If the reaction is endothermic, then heat is absorbed which means that heat is on the reactant's side. If temperature is increased then the reaction would shift to the right favoring production of the products.
by Anuk Burli 2C
Sun Nov 30, 2014 1:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: net ionic equation
Replies: 1
Views: 286

Re: net ionic equation

Hi
I think you use the net ionic equation when most of the reactants and products are ions or in aqueous solution
by Anuk Burli 2C
Fri Nov 28, 2014 2:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conceptional Question abut Equilibrium Constant
Replies: 2
Views: 393

Re: Conceptional Question abut Equilibrium Constant

In case you wanted to know though, I think if Delta G or Gibb's free energy is negative then K is larger and if Delta G is positive then K will be small. This is due to the equation Delta G= -RTln(K)
by Anuk Burli 2C
Sun Nov 02, 2014 4:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear structure for VESPR models
Replies: 2
Views: 482

Re: Linear structure for VESPR models

Hi, From what I think, the molecule is made up of 5 sp3d orbitals. three of these orbitals are arranged around the center which contain the 3 lone pairs. However 2 of the orbitals are arranged at 90 degrees from the three other orbitals. So while the electron arrangement is trigonal bipyramidal, the...
by Anuk Burli 2C
Wed Oct 29, 2014 10:07 pm
Forum: Lewis Structures
Topic: On Resonance and Stability
Replies: 1
Views: 227

Re: On Resonance and Stability

Hi,

The most stable lewis structure is the one where each element has the lowest formal charge or the formal charge closest to 0.
by Anuk Burli 2C
Sat Oct 25, 2014 5:58 pm
Forum: Resonance Structures
Topic: Basic Resonance purpose question
Replies: 3
Views: 662

Re: Basic Resonance purpose question

Hi,

We use resonance because of the limitations of a single lewis structure. The bonds aren't actually alternating between single, double, and triple bonds but resonance structures are a way to show the average bond length that a single lewis structure cannot show.
by Anuk Burli 2C
Sun Oct 19, 2014 4:24 pm
Forum: Quantum Numbers and The H-Atom
Topic: Finding Orbitals from Quantum Numbers
Replies: 4
Views: 1285

Re: Finding Orbitals from Quantum Numbers

Hi, if the quantum number n is equal to 6 and the quantum number l is equal to 3 then you know that those two quantum numbers correspond with 6f. There are 7 orbitals for f. You add 2 orbitals for each level. For example s has 1 orbital, p has 3 orbitals, d has 5 orbitals and f has 7 orbitals.
by Anuk Burli 2C
Mon Oct 13, 2014 3:53 pm
Forum: Quantum Numbers and The H-Atom
Topic: Electron Spin
Replies: 1
Views: 365

Re: Electron Spin

Hi, The magnetic spin quantum number refers to the angular momentum of an electron. Angular momentum is a vector so it has magnitude (1/2) and direction (+/-). The electrons "spin" a certain direction because electrons tend to fill orbitals before they pair up. If there are two electrons i...

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