Search found 61 matches

by Sara Lakamsani 4D
Sun Mar 17, 2019 1:43 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effects of Compression
Replies: 5
Views: 145

Effects of Compression

Compression of a reaction only has an effect if all of the agents are in gas phase right? Because that is the only way a difference in moles between the sides of the reaction would cause a pressure difference?
by Sara Lakamsani 4D
Sat Mar 16, 2019 11:51 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding an Inert Gas
Replies: 4
Views: 128

Adding an Inert Gas

Will adding an inert gas cause a shift if it increases the overall pressure of the system? I mean, will it cause the reaction to shift towards the side that has less molecules or moles if there is one?
by Sara Lakamsani 4D
Sat Mar 16, 2019 10:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Partial Pressures
Replies: 1
Views: 117

Partial Pressures

When applying Le Chateliers to partial pressures, should we think about it in terms of compressing the entire reaction or changing the amount of a given reactant or product present?
by Sara Lakamsani 4D
Sat Mar 16, 2019 10:08 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molecular Interlude
Replies: 5
Views: 179

Re: Molecular Interlude

Hope you figured it out!
by Sara Lakamsani 4D
Sat Mar 16, 2019 10:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW problem 4B. 13
Replies: 5
Views: 186

Re: HW problem 4B. 13

Hope this helped!
by Sara Lakamsani 4D
Sat Mar 16, 2019 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Solids and Liquids
Replies: 4
Views: 140

Re: Pure Solids and Liquids

Thank you guys for your responses!
by Sara Lakamsani 4D
Sat Mar 16, 2019 10:00 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Negative pH
Replies: 12
Views: 289

Re: Negative pH

Thanks for all your responses!
by Sara Lakamsani 4D
Sat Mar 16, 2019 9:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Kc
Replies: 6
Views: 162

Re: K and Kc

Hope this helps!
by Sara Lakamsani 4D
Sat Mar 16, 2019 9:57 pm
Forum: Calculating Work of Expansion
Topic: Units
Replies: 5
Views: 161

Re: Units

Thank you!
by Sara Lakamsani 4D
Sat Mar 16, 2019 9:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Kc
Replies: 6
Views: 162

Re: K and Kc

K can be used interchangeably to refer to the equilibrium constant using partial pressures or concentration. Sometimes you will see Kp when using partial pressures or Kc when using concentrations. If there is no subscript, partial pressures are probably being used, but you should be able to tell bas...
by Sara Lakamsani 4D
Sat Mar 16, 2019 9:51 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: [H2O] omitted??
Replies: 2
Views: 130

Re: [H2O] omitted??

Yes, because it is in such large excess
by Sara Lakamsani 4D
Sat Mar 16, 2019 9:50 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Free Expansion
Replies: 3
Views: 123

Re: Free Expansion

This means that no energy was put into the system to initiate expansion
by Sara Lakamsani 4D
Sat Mar 16, 2019 9:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 5G
Replies: 2
Views: 128

Re: Question 5G

Hope you figured it out!
by Sara Lakamsani 4D
Sun Feb 10, 2019 9:30 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm 2019
Replies: 9
Views: 158

Re: Midterm 2019

The midterm covers everything through the end of entropy in Outline 4
by Sara Lakamsani 4D
Sun Feb 10, 2019 9:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Term Differences (Heat, Enthalpy, Temperature, and Work)
Replies: 4
Views: 148

Re: Term Differences (Heat, Enthalpy, Temperature, and Work)

Heat is actually kind of difficult to define but I think the best way I've heard it described is the energy that is exchanged between a system and it's surroundings due to a difference in pressure. Temperature is just a scale we use to measure the intensity of heat which is why we often use degrees ...
by Sara Lakamsani 4D
Sun Feb 10, 2019 8:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Molecular Interlude
Replies: 5
Views: 179

Re: Molecular Interlude

I think anything of that nature that we would need on a test would be given to us.
by Sara Lakamsani 4D
Tue Feb 05, 2019 9:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy of Vaporization
Replies: 2
Views: 140

Enthalpy of Vaporization

Would we find an enthalpy of vaporization of a substance essentially the same way we find heat capacity?
by Sara Lakamsani 4D
Tue Feb 05, 2019 9:32 pm
Forum: Calculating Work of Expansion
Topic: Units
Replies: 5
Views: 161

Re: Units

I guess I just don't understand how, when using pdeltav, atm(L) gives us joules
by Sara Lakamsani 4D
Tue Feb 05, 2019 9:24 pm
Forum: Calculating Work of Expansion
Topic: Units
Replies: 5
Views: 161

Units

When we're using the ideal gas law or calculating work of expansion in general, what units of pressure and volume should we be using?
by Sara Lakamsani 4D
Tue Feb 05, 2019 9:11 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW problem 4B. 13
Replies: 5
Views: 186

Re: HW problem 4B. 13

We use the second equation when the external pressure is not constant, so in any reversible process
by Sara Lakamsani 4D
Tue Jan 15, 2019 9:17 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Negative pH
Replies: 12
Views: 289

Negative pH

Can be pH be negative? If the concentration of H+ is over 1, then the -log of it would be negative right?
by Sara Lakamsani 4D
Tue Jan 15, 2019 8:07 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Question on 6th Edition 6A.21
Replies: 2
Views: 51

Question on 6th Edition 6A.21

How do I find [H3O+] with Kw and temperature given?
by Sara Lakamsani 4D
Sun Jan 13, 2019 9:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Solids and Liquids
Replies: 4
Views: 140

Pure Solids and Liquids

I still don't quite understand why we discount pure solids and liquids. Can someone help explain?
by Sara Lakamsani 4D
Sun Jan 13, 2019 9:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Effect of increased concentration on equilibrium
Replies: 9
Views: 315

Re: Effect of increased concentration on equilibrium

More product will be produced until equilibrium of concentrations is restored.
by Sara Lakamsani 4D
Sun Jan 13, 2019 9:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 5G
Replies: 2
Views: 128

Re: Question 5G

Which question in 5G are you talking about?
by Sara Lakamsani 4D
Sun Dec 09, 2018 1:01 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Strong/weak acids and bases
Replies: 2
Views: 78

Re: Strong/weak acids and bases

If it is an acid like HF or HCl, the easiest thing to look at is atomic radius, Cl has a larger atomic radius therefore the bond to the H is longer and weaker, making it more likely to donate the H. That makes it a stronger acid. The other thing to look for is resulting ion stability. Once the proto...
by Sara Lakamsani 4D
Sun Dec 09, 2018 12:41 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Test 3 6b
Replies: 2
Views: 159

Re: Test 3 6b

Polarizing power has to do with the strength of the nuclear charge. Smaller atoms have higher polarizing power because there is less shielding of the positive charge. With that information, we know that Li+ has a higher polarizing power than Ca2+ which has a higher polarizing power than Cs+ and Ba2+...
by Sara Lakamsani 4D
Sun Dec 09, 2018 12:33 am
Forum: Biological Examples
Topic: Examples To Know
Replies: 1
Views: 117

Re: Examples To Know

I believe that's the extent of what he went over in class.
by Sara Lakamsani 4D
Sun Dec 09, 2018 12:32 am
Forum: Quantum Numbers and The H-Atom
Topic: quantum number, spin
Replies: 3
Views: 196

Re: quantum number, spin

There are only two options for ms or spin, usually denoted as +1/2 or -1/2. Electrons that are in the same orbital must have opposite spins.
by Sara Lakamsani 4D
Sat Dec 08, 2018 10:00 pm
Forum: DeBroglie Equation
Topic: exhibiting wave-like properties
Replies: 1
Views: 125

exhibiting wave-like properties

Could someone remind me of the minimum wavelength at which a particle is said to exhibit wave-like properties?
by Sara Lakamsani 4D
Sun Dec 02, 2018 8:19 pm
Forum: Hybridization
Topic: S Hybridization?
Replies: 5
Views: 83

Re: S Hybridization?

It's usually for atoms that are not central, like hydrogen.
by Sara Lakamsani 4D
Sun Dec 02, 2018 8:15 pm
Forum: Hybridization
Topic: Double and Triple Bonds
Replies: 17
Views: 213

Re: Double and Triple Bonds

They just add un-hybridized orbitals. The hybrid orbital stays the same but the extra electrons are held in p orbitals.
by Sara Lakamsani 4D
Sun Dec 02, 2018 8:10 pm
Forum: Lewis Acids & Bases
Topic: 6th editions Fundamentals J #1
Replies: 3
Views: 70

Re: 6th editions Fundamentals J #1

I think it is because, in water, the H atoms in H2SO3 are likely to be attracted to the oxygen and form H3O whereas Ca(OH)2 dissociates into Ca and OH ions
by Sara Lakamsani 4D
Sun Nov 18, 2018 1:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Bond Angles
Replies: 3
Views: 49

Re: Seesaw Bond Angles

Ok thanks. From my discussion, I was under the impression that the trigonal planar pairs were affected, but not the linear ones. And also, often, in the textbook, it just says 90 and 120 in the solutions manual for seesaw structures rather than slightly less than 90 and 120. Do you know if it would ...
by Sara Lakamsani 4D
Sun Nov 18, 2018 1:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral
Replies: 2
Views: 74

Re: Octahedral

They are named by the shape they form. If you were to connect the dots between four areas of electron density in our model, it would form a 3d shape with 4 triangular faces or planes so we call it tetrahedral. If you do this with the arrangement of 6 areas of electron density, it forms a 3d shape wi...
by Sara Lakamsani 4D
Sun Nov 18, 2018 1:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Bond Angles
Replies: 3
Views: 49

Seesaw Bond Angles

I'm a little confused about how the lone pair affects the bond angles in the seesaw geometry. Why does the lone pair not affect the 90 and 180 bond angles?
by Sara Lakamsani 4D
Sun Nov 11, 2018 7:06 pm
Forum: Lewis Structures
Topic: Ionic compound
Replies: 4
Views: 99

Re: Ionic compound

Yes, I believe you draw the valence electrons around the atom that takes them and note the charges with brackets, but no lines because those indicate electron pairs that are shared covalently.
by Sara Lakamsani 4D
Sun Nov 11, 2018 7:03 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Importance of Dissociation Energy
Replies: 1
Views: 45

Re: Importance of Dissociation Energy

Dissociation energy is the amount of energy required to break a bond, so the stronger the bond. It's just important to know that the bond between ions is stronger than the bond between dipoles so that you know how certain molecules are likely to interact once you know which forces are acting on them.
by Sara Lakamsani 4D
Sun Nov 11, 2018 6:52 pm
Forum: Resonance Structures
Topic: Hybrid Resonance
Replies: 4
Views: 232

Re: Hybrid Resonance

I believe it just refers to the actual structure of the molecule which would be a hybrid of all of the resonance structures
by Sara Lakamsani 4D
Wed Oct 31, 2018 10:50 pm
Forum: Lewis Structures
Topic: The Number of Valence Electrons in Transition Metals
Replies: 2
Views: 74

Re: The Number of Valence Electrons in Transition Metals

You need to write out the electron configuration of the element and then count the electrons in levels past the last noble gas, so for Mn, it would be the number of additional electrons it has after [Ar].
by Sara Lakamsani 4D
Wed Oct 31, 2018 12:02 am
Forum: Ionic & Covalent Bonds
Topic: Predicting which orbital an electron should be removed from to create 1+ ion
Replies: 2
Views: 64

Re: Predicting which orbital an electron should be removed from to create 1+ ion

Copper has a full 3d orbital. Cu: [Ar]3d^104s^1 The way Gail explained it today is that, although 4s is at a higher energy level, there is an additional energy cost to disrupting that full orbital, and since the difference between energy levels get smaller and smaller, it ends up requiring less ener...
by Sara Lakamsani 4D
Tue Oct 30, 2018 11:49 pm
Forum: Ionic & Covalent Bonds
Topic: Ground states (homework problem 2A.11)
Replies: 2
Views: 69

Re: Ground states (homework problem 2A.11)

The problem is telling you that when 3 electrons are removed from some metal (giving it a +3 charge), its electron configuration is [Ar]3d^6. Using the atomic number of Ar and the information that there are 6 additional electrons, you know that this mystery ion has 24 electrons. So you know that the...
by Sara Lakamsani 4D
Tue Oct 30, 2018 11:38 pm
Forum: Ionic & Covalent Bonds
Topic: 2B.1 Part B
Replies: 2
Views: 50

Re: 2B.1 Part B

I believe it is because carbon has the lowest ionization energy, and the atom with the lowest ionization energy is generally the central atom because it shares its electrons more readily.
by Sara Lakamsani 4D
Sun Oct 28, 2018 5:43 pm
Forum: Properties of Electrons
Topic: Coulomb
Replies: 4
Views: 235

Re: Coulomb

I believe it is just the force of attraction between oppositely charged particles; particles of opposite charges are attracted to each other, while particles with the same charge repel each other.
by Sara Lakamsani 4D
Sun Oct 28, 2018 5:20 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Affinity
Replies: 1
Views: 80

Re: Electron Affinity

You need to take into account the trends of electron affinity based on the periodic table. So, electron affinity decreases as you go down a group, because electrons are farther away from the nucleus and there is increased shielding because electrons are at higher energy levels. It increases as you g...
by Sara Lakamsani 4D
Sat Oct 27, 2018 3:58 pm
Forum: Lewis Structures
Topic: When electrons do no pair in orbitals:
Replies: 2
Views: 31

Re: When electrons do no pair in orbitals:

So, I think you're talking about Hund's rule: that every orbital in a subshell must have one electron before any of them can have a pair. This is because is creates the lowest possible energy. Electrons repel each other so if they are in the same orbital, that repulsion creates a higher energy state.
by Sara Lakamsani 4D
Sun Oct 21, 2018 7:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Exam 2
Replies: 4
Views: 130

Re: Exam 2

I believe Dr. Lavelle said that we will always have a full sheet of equations like on the first exam.
by Sara Lakamsani 4D
Sun Oct 21, 2018 7:24 pm
Forum: *Shrodinger Equation
Topic: Wavelike Properties
Replies: 1
Views: 104

Re: Wavelike Properties

The double-slit experiment showed that electrons form wave-like interference patterns that curve around a barrier rather than going straight through the slit like a particle
by Sara Lakamsani 4D
Sun Oct 21, 2018 7:22 pm
Forum: Photoelectric Effect
Topic: Kinetic Energy
Replies: 3
Views: 74

Re: Kinetic Energy

Yes, due if there is excess energy in removing the electron, it is conserved as kinetic energy of the electron. And the work function is the same as the amount of energy required to remove the electron
by Sara Lakamsani 4D
Sun Oct 21, 2018 7:15 pm
Forum: Photoelectric Effect
Topic: Conditions that allow electron to be ejected from metal surface
Replies: 12
Views: 365

Re: Come nditions that allow electron to be ejected from metal surface

Yes. Both are true. Just bear in mind that if the energy of the photon is higher than the energy required to remove the electron, the remaining energy will present as kinetic energy of the ejected electron; the energy is conserved.
by Sara Lakamsani 4D
Sun Oct 14, 2018 3:38 pm
Forum: Properties of Light
Topic: Geiger and Marsden experiment
Replies: 3
Views: 42

Re: Geiger and Marsden experiment

So, the positively charged alpha particles were only deflected if the got close to the nucleus?
by Sara Lakamsani 4D
Sun Oct 14, 2018 3:23 pm
Forum: Properties of Light
Topic: Colors and Frequency
Replies: 13
Views: 411

Re: Colors and Frequency

It would help to have a general sense of how wavelength corresponds to the type of EM radiation, just because it would be easier to understand the real world implications of the practice problems. It would help you to know whether we're dealing with visible light or x-rays etc., but I'm not sure if ...
by Sara Lakamsani 4D
Sun Oct 14, 2018 3:16 pm
Forum: Properties of Light
Topic: Wave vs. Particle Behavior
Replies: 5
Views: 87

Re: Wave vs. Particle Behavior

In a double slit experiment, it was shown that electrons formed an diffraction pattern like light waves, bending around the barriers, but electrons also have mass and can collide with and transfer energy to other particles.
by Sara Lakamsani 4D
Thu Oct 04, 2018 10:19 pm
Forum: Significant Figures
Topic: Using Sig Figs Throughout a Problem?
Replies: 6
Views: 90

Re: Using Sig Figs Throughout a Problem?

My TA said to treat it as if you did all of the intermediate calculations in one step. In other words, you only need to use sig figs in your final answer. I normally just use the numbers stored in my calculator throughout the problem and then write my answer with the correct number of sig figs.
by Sara Lakamsani 4D
Thu Oct 04, 2018 9:59 pm
Forum: Balancing Chemical Reactions
Topic: L.5 Mass
Replies: 3
Views: 77

Re: L.5 Mass

You do need to convert to moles using the molar mass of each compound. You shouldn't need avogadro's number. Just convert the kg of NH4ClO4 to g and then to moles and you would need (5/3)x as many moles of Al so that the two reactants are proportional according to the molar ratios of the equation. T...
by Sara Lakamsani 4D
Thu Oct 04, 2018 9:16 pm
Forum: SI Units, Unit Conversions
Topic: L35 Tons Conversion Rate
Replies: 4
Views: 94

Re: L35 Tons Conversion Rate

I believe you do have to convert to grams, because you will need to use molar ratios and molar masses are measured to g/mol^-1. I found that there are 907185 g in one US ton.
by Sara Lakamsani 4D
Thu Oct 04, 2018 8:29 pm
Forum: Significant Figures
Topic: Limiting Reactants
Replies: 6
Views: 91

Re: Limiting Reactants

To find the limiting reactant, you need to compare the moles of each reactant, not the masses. To start, make sure you have balanced equation to represent the reaction. This will tell you the molar ratio in which the compounds react with each other. For example, if you have 4NH_{3}+5O_{2}\rightarrow...

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