Search found 27 matches

by Ani Galfayan 1H
Wed Mar 09, 2016 9:24 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Winter 2011 final question 1
Replies: 2
Views: 357

Re: Winter 2011 final question 1

You can also look at it in the way that q(sys) = -q(surr) so if methane gas is the system and the water is the surrounding then in relation to methane the water would have negative heat. Thus dividing the negatives would leave you with a positive value.
by Ani Galfayan 1H
Sat Mar 05, 2016 8:42 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Identifying Cis and Trans from Line Structues
Replies: 2
Views: 362

Re: Identifying Cis and Trans from Line Structues

it helps to draw it out using lewis structures and add the hydrogens. it'll be more visible to identify the group with higher priority.
by Ani Galfayan 1H
Sun Feb 28, 2016 4:42 pm
Forum: *Nucleophiles
Topic: Ambident Nucleophile
Replies: 2
Views: 436

Ambident Nucleophile

How can I tell if a nucleophile is ambident? Does it have to do with resonance?
by Ani Galfayan 1H
Mon Feb 22, 2016 4:57 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Pre-equilibrium approach
Replies: 3
Views: 763

Re: Pre-equilibrium approach

where does the 1/2 in 1/2 d[NO2]/dt come from? is this related to how -1/a [dA]/dt = 1/c [dC]/dt ? and what happens if there are multiple products in the final step, how would you write the slow step's rate?
by Ani Galfayan 1H
Mon Feb 15, 2016 4:28 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units of k
Replies: 3
Views: 507

Re: Units of k

To determine what order reaction we're dealing with, would it be sufficient to just look at the units of k given in the problem? For example if k is in (L mole-1 s-1) with that information would we be able to say it's a second order reaction?
by Ani Galfayan 1H
Mon Feb 08, 2016 7:22 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Midterm 2011 question 1
Replies: 1
Views: 362

Re: Midterm 2011 question 1

From what I understand, because q(sys) = -q(surr) we can say that the system is the reaction and the surrounding is the calorimeter. This is where the negative comes from. The conversion to moles comes into play because we're using the enthalpy to get q. the need for conversion can also be noticed w...
by Ani Galfayan 1H
Tue Feb 02, 2016 7:55 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 1
Views: 250

Re: Oxidation Numbers

We know generally that the oxidation state for each O is -2, and the entire molecule MnO4- has a -1 charge as given. To find out the oxidation state of Mn, we would do (Mn) + 4(-2) = -1 and solving this would give you +7. Mn2+ having a charge of 2+ is just given within.
by Ani Galfayan 1H
Tue Feb 02, 2016 6:15 pm
Forum: Balancing Redox Reactions
Topic: 14.1 Book HW
Replies: 3
Views: 459

Re: 14.1 Book HW

By looking at each atom individually, we can count the oxidation states and calculate the unknown. Breaking up C2H5OH, we know that each O has an oxidation state of -2 and each H, +1. We want the total to equal 0 so we do the following 2(C) + 6(+1) + (-2) = 0 C = -4/2 = -2 We do the same for C2H4O.....
by Ani Galfayan 1H
Tue Jan 26, 2016 11:48 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Question 11 from Quiz 1 Preparation - Winter 2015
Replies: 2
Views: 455

Re: Question 11 from Quiz 1 Preparation - Winter 2015

Regarding the second question, you're right about the process and using that formula. I think there must've been a mistake in your calculations. Once I solved for the heat absorbed by the water, +23.8 kJ, I then set up my equation as 23800=n (75.29)(100-25). solving for n gave me approximately 4.21 ...
by Ani Galfayan 1H
Mon Jan 18, 2016 8:58 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Which Has Higher Entropy?
Replies: 1
Views: 3046

Which Has Higher Entropy?

In general, how can one tell which compound has higher molar entropy? I know that there are a number of different factors that can change entropy. For example, gases are more random than liquids which are more random than solids. I know the number of moles and the size of the molecule are important ...
by Ani Galfayan 1H
Sun Jan 17, 2016 5:18 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Reversible and irreversible
Replies: 2
Views: 410

Re: Reversible and irreversible

A process is reversible if an infinitely small change can reverse the direction. A reversible process is in equilibrium. This process is carried out in innumerable small steps. Therefore the work can be pictured as the area under a curve. Work is maximized. An irreversible process is one that can no...
by Ani Galfayan 1H
Wed Jan 13, 2016 2:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacities
Replies: 1
Views: 317

Re: Heat Capacities

In a perfect system q(sys) + q(surr) = 0. This occurs when there is no loss of heat. The surrounding "gains" what the system "loses" and the surrounding "loses" what the system "gains". (heat lost) + (heat gained) = 0 When you rearrange that equation you get q...
by Ani Galfayan 1H
Wed Jan 06, 2016 7:50 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Isothermal Expansion
Replies: 2
Views: 425

Re: Isothermal Expansion

Isothermal means constant temperature. To maintain a constant temperature, the system is typically immersed in a water bath. In an isothermal expansion, the pressure of the gas falls as it expands (Boyle's law - states that the pressure and volume of a gas have an inverse relationship when temperatu...
by Ani Galfayan 1H
Sat Dec 05, 2015 1:38 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic
Replies: 2
Views: 661

Re: Isoelectronic

Isoelectronic means that the atom and ion have the same number of electrons. So to answer your question, yes it is because they both have 18 electrons. Another example is Na+ Mg2+ and F-. They are isoelectronic because they all have 10 electrons.
I hope that helps!
by Ani Galfayan 1H
Fri Dec 04, 2015 9:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q6B from 2012 Final
Replies: 1
Views: 230

Q6B from 2012 Final

This problem asks to calculate the percentage of PCL5 that dissociates if 0.05 mole of PCL5 is placed in a closed vessel at 250 degrees Celsius and 2.00 atm. The equilibrium constant Kc = 0.045. I understand how to calculate the volume but I'm confused as to how the equilibrium equation is set up. C...
by Ani Galfayan 1H
Mon Nov 30, 2015 6:52 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa/pKb and Strength of an Acid/Base
Replies: 1
Views: 832

Re: pKa/pKb and Strength of an Acid/Base

The lower the pKa, the stronger the acid. And the same relationship does go for bases. The lower the pKb the stronger the base.
by Ani Galfayan 1H
Mon Nov 30, 2015 5:06 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH of Weak Acids and Bases
Replies: 1
Views: 298

pH of Weak Acids and Bases

When calculating the pH of weak acids and bases, when are we justified to approximate the x value as approaching 0? For example in homework problem 12.55 part a, after writing the equation for the equilibrium constant as \frac{x^{2}}{(0.20-x)} = Ka = 1.8\times{10^{-5}} , we approximate it to...
by Ani Galfayan 1H
Fri Nov 27, 2015 6:12 pm
Forum: Polyprotic Acids & Bases
Topic: Approximation Justification
Replies: 2
Views: 599

Re: Approximation Justification

During last Friday's lecture, Dr. Lavelle said that in this class we won't be seeing calculations involving polyprotic acids, but only set ups. If we're given a calculation, we would be given Ka1 just for step 1 and asked to treat it as an individual step. We'd ignore that some goes to the next step...
by Ani Galfayan 1H
Wed Nov 18, 2015 3:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Number of binding sites
Replies: 1
Views: 321

Re: Number of binding sites

One way to determine the number of binding sites a ligand has is just by looking at the molecular formula. For example in ethylenediamine molecule (NH2CH2CH2NH2) there are 2 nitrogen atoms each with a lone pair of electrons, which means they both act as bonding sites, making the ligand a bidentate. ...
by Ani Galfayan 1H
Mon Nov 09, 2015 3:45 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 8
Views: 1074

Re: Polydentate

So to find out how many places a ligand can bond, would we have to draw the Lewis structure to determine how many lone pairs there are?
by Ani Galfayan 1H
Wed Nov 04, 2015 11:48 am
Forum: Ionic & Covalent Bonds
Topic: LiH vs HCl
Replies: 2
Views: 336

Re: LiH vs HCl

Also, 1st and 2nd group elements tend to make ionic bonds
by Ani Galfayan 1H
Fri Oct 30, 2015 8:23 pm
Forum: Dipole Moments
Topic: Polarity of O3
Replies: 1
Views: 1089

Re: Polarity of O3

To determine if a molecule is polar, you would draw the Lewis structure. Once you draw O3, you can see that the central O has a lone pair. With 3 regions of electron density, one being the lone pair, you can identify the molecule as having a bent shape. We know that a bent shape is polar, therefore ...
by Ani Galfayan 1H
Sun Oct 25, 2015 7:33 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: MO Energy Level Diagram
Replies: 1
Views: 260

MO Energy Level Diagram

How do I know which molecular orbital energy level diagram to use in each case? Do i look at whether the molecules are homonuclear or heteronuclear? or do I look at whether the nuclear charge for each atom is greater than or less than 8? or both?
by Ani Galfayan 1H
Wed Oct 21, 2015 2:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Cis and Trans Dichloroethene
Replies: 3
Views: 331

Re: Cis and Trans Dichloroethene

The prefix "cis-" means that the chlorine atoms are on the same side of the double bond. This positioning also makes the molecule polar due to the asymmetry (the dipoles don't cancel). "Trans-" means the chlorine atoms are located on the same side. This positioning make the dipol...
by Ani Galfayan 1H
Wed Oct 14, 2015 10:17 am
Forum: DeBroglie Equation
Topic: What equation do I use?
Replies: 1
Views: 348

Re: What equation do I use?

On problems where you're given the speed/velocity and mass of an object, you use the equation where p = mass x velocity.
Make sure the units match up, where mass has to be in kg due to Planck's constant.
by Ani Galfayan 1H
Mon Oct 05, 2015 9:08 pm
Forum: Trends in The Periodic Table
Topic: Orbitals and the Periodic Table
Replies: 1
Views: 317

Re: Orbitals and the Periodic Table

Hopefully this image clears it up a bit. It's on page 45 from our textbook. The s-block includes the first two columns from the left-hand side (Li - Be), p-block includes the last 6 columns (B - He), d-block includes the columns from Sc - Zn, and the f-block includes the two rows of Lanthanoids and ...
by Ani Galfayan 1H
Sat Oct 03, 2015 5:18 pm
Forum: Photoelectric Effect
Topic: Light Intensity
Replies: 2
Views: 374

Re: Light Intensity

The photoelectric effect shows how light has the properties of a particle, such as when it interacts with metal. If light was acting like a wave, higher intensity would mean higher energy, but that was not the case. Therefore no electrons were ejected. Since light was acting like a particle (with pa...

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