Search found 28 matches

by Kevin Liu 3G
Sat Dec 09, 2017 4:08 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Using electronegativity to determine acidity
Replies: 2
Views: 326

Re: Using electronegativity to determine acidity

Bases generally have a metal within them and acids generally have a nonmetal (HCl, HBr, HI). Amphoteric compounds generally have a metalloid with the exception of H2O i believe. Also, the higher up you move on the periodic table the less acidic something is (HI is more acidic than HCl).
by Kevin Liu 3G
Sat Dec 09, 2017 4:05 pm
Forum: Lewis Acids & Bases
Topic: 4C
Replies: 2
Views: 206

Re: 4C

Lewis acids accept electrons. The Ni3+ has a positive charge which means it accepts electrons hence the overall charge of the complex is 0.
by Kevin Liu 3G
Sat Dec 09, 2017 3:57 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Calculations [ENDORSED]
Replies: 3
Views: 306

Re: Limiting Reactant Calculations [ENDORSED]

Based off of the question, they are trying to clean up the acid H2SO4(aq) so it is safe to assume there would be more acid than the substance used to neutralize the spill. If they tell you the mass of both substances you would convert it to moles and go from there to find the limiting reactant.
by Kevin Liu 3G
Sat Dec 09, 2017 3:55 pm
Forum: Balancing Chemical Reactions
Topic: Fundamentals J
Replies: 2
Views: 225

Re: Fundamentals J

If it helps, the net ionic equation is generally shorter than the ionic equation so that's a good tip to remember.
by Kevin Liu 3G
Sat Dec 09, 2017 3:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: Solutions
Replies: 1
Views: 192

Re: Solutions

It should be .0024 grams of NaOH because molarity is moles/liters. The solution is given in milliliters so you have to convert that to liters. To solve for the part you're asking about, you do MV (initial) = MV (final) That means (2)(V) = (.250)(.650) Then you solve for V to know how much stock solu...
by Kevin Liu 3G
Fri Dec 01, 2017 3:51 pm
Forum: Conjugate Acids & Bases
Topic: Chemical Formula
Replies: 5
Views: 362

Re: Chemical Formula

It's also helpful to remember that generally acids start with an H or end with -COOH while bases generally end with -OH. It might not be true for everything but is for most things I have encountered.
by Kevin Liu 3G
Fri Dec 01, 2017 3:44 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH of solutions not at 25 degrees C
Replies: 2
Views: 320

Re: pH of solutions not at 25 degrees C

pH drops as temperature increases, however, if you think of water, hotter water does not get more or less acidic so ultimately the concentrations of H+ and OH- are still the most important factors.
by Kevin Liu 3G
Sun Nov 26, 2017 1:10 pm
Forum: *Molecular Orbital Theory Applied To Transition Metals
Topic: Bond Order
Replies: 2
Views: 542

Re: Bond Order

If you just remember the basics you should be okay. Triple bonds are more stable and fewer bonds mean less stable. Also that the more bonds there are the closer the atoms are to each other.
by Kevin Liu 3G
Sun Nov 26, 2017 1:08 pm
Forum: Biological Examples
Topic: Which direction would the reaction proceed if:
Replies: 2
Views: 508

Re: Which direction would the reaction proceed if:

If the reaction would move from left to right if you double one side and quadruple the other. You just have to think about the reaction as a scale with products on one side and reactants on the other. This scale wants to be in balance and for that to happen you must move something from the lower sid...
by Kevin Liu 3G
Sun Nov 26, 2017 1:03 pm
Forum: Limiting Reactant Calculations
Topic: two-step reaction limiting reactant problems
Replies: 2
Views: 366

Re: two-step reaction limiting reactant problems

Hi, so in this example, the CH4 is the limiting reactant in step 1. You would find the moles of CH4 (.00225) and the moles of H2O (.006) and calculate the moles of CO created. From that you would use the moles of CO and remaining H2O in step 2. Whichever one of those is the limiting reactant there w...
by Kevin Liu 3G
Thu Nov 16, 2017 11:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Exceptions to the Octet Rule
Replies: 4
Views: 311

Re: Exceptions to the Octet Rule

Exceptions to the octet rule can occur after n = 3. This makes sense once you take into account the d orbital meaning that the atom has so much more room for others to bond. There are also exceptions where the central atom is under 8 electrons and I believe Boron is one example of this.
by Kevin Liu 3G
Thu Nov 16, 2017 11:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 2
Views: 168

Re: Bond Angles

You look at the electron distribution to tell the angles (only if there are lone pairs of electrons). If there isn't, then you go by the molecular formula for the molecule you're looking at.
by Kevin Liu 3G
Thu Nov 16, 2017 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Notation
Replies: 2
Views: 204

Re: VSEPR Notation

The A in the VSEPR notation means central atom. The X would be the number of atoms surrounding the central atom and E is the number of lone pairs around the central atom (A).
by Kevin Liu 3G
Thu Nov 09, 2017 3:53 pm
Forum: Hybridization
Topic: Writing out the Hybridization [ENDORSED]
Replies: 4
Views: 339

Re: Writing out the Hybridization [ENDORSED]

Px, Py, and Pz are used to show which way the subshell is oriented (just think of the x, y, and z axis).
by Kevin Liu 3G
Tue Nov 07, 2017 4:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.3
Replies: 1
Views: 133

4.3

For part A, I am getting 10 electrons from HCN where there is one bond between hydrogen and carbon and three bonds between carbon and nitrogen with one lone pair on nitrogen. Is that shape still linear?
by Kevin Liu 3G
Tue Oct 31, 2017 4:23 pm
Forum: Lewis Structures
Topic: 3.39
Replies: 2
Views: 179

Re: 3.39

You can think of it as the metals, Na or K, lose their electron so there won't be much of a lewis structure to draw anyways.
by Kevin Liu 3G
Tue Oct 31, 2017 4:14 pm
Forum: Lewis Structures
Topic: Elements that have extended octets
Replies: 3
Views: 208

Re: Elements that have extended octets

I believe anything after the 3rd row, so with the introduction of the d orbitals, can have an expanded octet.
by Kevin Liu 3G
Tue Oct 31, 2017 4:12 pm
Forum: Lewis Structures
Topic: 3.33 Part C
Replies: 3
Views: 233

3.33 Part C

For part C it wants the Lewis structure for ONF. I did the structure and there has to be a double bond somewhere in order for all 18 e- to be accounted for. But where would the double bond be? To the O or the F?
by Kevin Liu 3G
Sun Oct 29, 2017 10:32 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity versus ionization energy [ENDORSED]
Replies: 3
Views: 262

Re: Electron affinity versus ionization energy [ENDORSED]

They are not technically the same thing but they have the same trends. Electron affinity is essentially how likely it is an element is to form an ion whereas ionization energy is the energy needed for said element to form an ion. So one is the likeliness of an element being an ion while the other is...
by Kevin Liu 3G
Sun Oct 29, 2017 10:26 pm
Forum: Properties of Electrons
Topic: Energy level question [ENDORSED]
Replies: 2
Views: 277

Re: Energy level question [ENDORSED]

It helps to think of the diagram that Professor Lavelle draws within class with n = 1 on the bottom followed by n = 2 and so forth. n = 1 is the lowest on the diagram meaning there is no energy for it to lose, emit as a photon, thus it is the lowest energy state.
by Kevin Liu 3G
Sun Oct 29, 2017 10:19 pm
Forum: Hybridization
Topic: Question 4.39 [ENDORSED]
Replies: 4
Views: 357

Re: Question 4.39 [ENDORSED]

If it helps, think of each P atom, with equal electronegativity, tugging in 4 directions which equals out the net force thus making the molecule non polar. It's essentially an electron tug of war with everyone of the same strength.
by Kevin Liu 3G
Thu Oct 19, 2017 2:27 pm
Forum: DeBroglie Equation
Topic: De Broglie's and Photoelectric Effect
Replies: 2
Views: 201

Re: De Broglie's and Photoelectric Effect

For any question, it depends on what you're looking for. De Broglie's equation connects wavelength, mass, and velocity whereas Ek connects energy, mass, and velocity. So in some questions you need both but the key point is that one equation can help you find wavelength, whereas the other one helps y...
by Kevin Liu 3G
Thu Oct 19, 2017 2:24 pm
Forum: DeBroglie Equation
Topic: Can we use formula E=mv^2 to calculate the total energy?
Replies: 2
Views: 211

Re: Can we use formula E=mv^2 to calculate the total energy?

I don't think that E and Ek are the same values so you can't exactly make the two equal. Ek is 1/2mv^2 whereas E is the energy needed to eject an electron. Also, for the questions relating Ek = E - work function most of the time Ek is 0 because the velocity is 0 meaning that the energy needed to eje...
by Kevin Liu 3G
Sat Oct 14, 2017 11:21 am
Forum: Properties of Light
Topic: De Broehli [ENDORSED]
Replies: 2
Views: 281

Re: De Broehli [ENDORSED]

For question 33, you set the KE and the energy needed to emit an electron equal to each other. 1/2mv^2 = hv - (symbol) then you solve for frequency.

Then to calculate wavelength you would use the equation lambda = hc/KE or hc/(1/2)mv^2. You should get 33.7 nm.
by Kevin Liu 3G
Sat Oct 14, 2017 11:11 am
Forum: Properties of Light
Topic: Balmer and Lyman Clarification [ENDORSED]
Replies: 3
Views: 206

Re: Balmer and Lyman Clarification [ENDORSED]

The experiments done to find those spectra were done with a hydrogen atom as Lavelle said in class. Thus, the Lyman and Balmer series are specific only to hydrogen.
by Kevin Liu 3G
Fri Oct 06, 2017 12:01 pm
Forum: Molarity, Solutions, Dilutions
Topic: question bout L.39
Replies: 1
Views: 188

Re: question bout L.39

I think the question you're referring to is L.37 (but I may be wrong and if so, I apologize) but for part A it wants something that is .5 M and 1 L from something that is 16 M. That means you do the MiVi = MfVf equation. (1)(.5) = (16)(V) then you solve for V and V should be 1/32 or .03125
by Kevin Liu 3G
Fri Oct 06, 2017 11:53 am
Forum: Molarity, Solutions, Dilutions
Topic: Molarity unit [ENDORSED]
Replies: 11
Views: 952

Re: Molarity unit [ENDORSED]

Yes, it is best to never do mol/ml because the formula always uses mol/L and it is the more accepted version. Besides, you wouldn't want the grade to mistakenly think that you wrote 13 L instead of 13 ml.
by Kevin Liu 3G
Fri Oct 06, 2017 11:52 am
Forum: Molarity, Solutions, Dilutions
Topic: G.5 [ENDORSED]
Replies: 2
Views: 350

Re: G.5 [ENDORSED]

After you get the M of NA2CO3, you have to figure out how many moles of NA+ there is. Since it says mmol it would be 2.15 x 10^-3 moles of Na2 but you want NA+ so you would divide (2.15 x 10^-3)/2 getting 1.075 x 10^3. Then you use the formula that V = n/M and you plug in the numbers and get 1.35 x ...

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