Search found 31 matches
- Mon Jun 11, 2018 8:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 4.7
- Replies: 3
- Views: 460
Re: Homework 4.7
Why wouldn't the angles be less than 120 degrees? Why is it 109.5?
- Thu Jun 07, 2018 3:29 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted vs Lewis acids
- Replies: 3
- Views: 687
Re: Bronsted vs Lewis acids
The definition of a Lewis acid is an electron pair acceptor. The definition of a Bronsted acid is a proton donor. On page 609 of the textbook, it says that "a Bronsted acid is a supplier of one particular Lewis acid, a proton". This makes sense since the Bronsted acid donates the electron ...
- Wed Jun 06, 2018 10:55 pm
- Forum: Bronsted Acids & Bases
- Topic: J11c
- Replies: 4
- Views: 660
Re: J11c
Chem_Mod wrote:Ca 2+ is a spectator ion; this should simplify things. The acid is the HI that gives off the proton and CaO is the proton acceptor, making it the base.
What is a spectator ion in relation to acids and bases? How would you identify one?
- Wed Jun 06, 2018 10:44 pm
- Forum: Bronsted Acids & Bases
- Topic: How to identify a Bronsted acid or base
- Replies: 11
- Views: 4419
Re: How to identify a Bronsted acid or base
How can you tell if it is a Bronsted acid or base without the reaction though? For example, on J1, you are asked to identify if it is a Bronsted acid or base just by the compound. How would you do this?
- Sun Jun 03, 2018 5:58 pm
- Forum: Hybridization
- Topic: σ vs π bond tips thread
- Replies: 5
- Views: 686
Re: σ vs π bond tips thread
It's also helpful to know that pi bonds will always be parallel p-orbitals overlapping and you can only have up to 2 pi bonds, which is why only up to triple bonds exist (1 sigma bond, 2 pi bonds).
- Sun Jun 03, 2018 5:47 pm
- Forum: Hybridization
- Topic: homework problem 4.35 part c
- Replies: 2
- Views: 385
Re: homework problem 4.35 part c
The above Lewis structure is correct because you have 28 electrons. Each F atom takes a full octet with a single bond in order to minimize formal charge. You can add the remaining 4 electrons on the central atom, Br because it is past row 3 and can take an expanded octet.
- Wed May 30, 2018 6:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HW 4.9
- Replies: 10
- Views: 2049
Re: HW 4.9
I thought it was trigonal bipyramidal because there are 5 regions of electron density. What is the difference between trigonal bipyramidal and T-shaped then?
- Thu May 24, 2018 1:51 pm
- Forum: Lewis Structures
- Topic: 3.45
- Replies: 2
- Views: 489
Re: 3.45
I'm a little bit confused on how you drew your original Lewis structure but the way I drew it was you start with N in the middle since it is the least electronegative atom with it connected to Cl and the 2 O's. As you mentioned, you have a single bond connected to Cl with a full octet surrounded it....
- Wed May 23, 2018 11:27 am
- Forum: Lewis Structures
- Topic: Radical HW 3.59
- Replies: 6
- Views: 813
Re: Radical HW 3.59
I don't really understand how you all are finding radicals. For example question 3.55 asks us to identify which of the following are radicals: NO2-, CH3, OH, CH2O. How do you know which are radicals? A radical means that you have an unpaired valence electron which means that you would have an odd n...
- Tue May 22, 2018 10:15 pm
- Forum: Lewis Structures
- Topic: Radical HW 3.59
- Replies: 6
- Views: 813
Radical HW 3.59
For 3.59 part a, the question asks for the Lewis structure of ClO. I know this will be a radical because it has 13 electrons but I put the single electron on the O so that the formal charges would be at 0. But, the solution manual has it on Cl and therefore the Cl would have a formal charge of +1 an...
- Wed May 16, 2018 11:52 am
- Forum: Resonance Structures
- Topic: Radicals
- Replies: 13
- Views: 1509
Re: Radicals
If you are asked to do a Lewis structure of a molecule with a radical, one of the biggest things to consider is the formal charge. Even though you have an odd number of electrons, it is still possible for some molecules to do a Lewis structure without any formal charges and you should make sure to w...
- Wed May 16, 2018 11:49 am
- Forum: Ionic & Covalent Bonds
- Topic: Percentage Ionic Character
- Replies: 4
- Views: 657
Re: Percentage Ionic Character
Will we be given the electronegativity of the elements so that we can determine if it is an ionic / covalent bond?
- Tue May 15, 2018 4:08 pm
- Forum: Lewis Structures
- Topic: Central atom
- Replies: 7
- Views: 884
Central atom
On homework question 3.33 part b, they asked for the lewis structure of COCl2. Which atom goes in the middle and how do you know this?
- Thu May 10, 2018 5:11 pm
- Forum: Photoelectric Effect
- Topic: Intensity of Photon
- Replies: 8
- Views: 1018
Re: Intensity of Photon
The reason why increasing the intensity didn't work was because the threshold energy wasn't reached. In order to reach threshold energy, you would need to increase frequency or decrease wavelength, since they are inversely proportional. After the photoelectric effect, they realized that this wasn't ...
- Tue May 08, 2018 10:27 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty calculation
- Replies: 1
- Views: 347
Re: Uncertainty calculation
Uncertainty in position is the Δx in the Heisenberg uncertainty equation which is ΔxΔp > h/4π. Δp is momentum, which also can be written as m*v. Therefore, you would rewrite the equation as ΔxmΔv > h/4π and then rewrite it so that Δx is isolated (since that is what you are solving for). You are give...
- Tue May 08, 2018 12:14 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Unicorn Practice Midterm #8
- Replies: 3
- Views: 688
Re: Unicorn Practice Midterm #8
If the question was asking "can you blame the Heisenberg Uncertainty Principle?" what would the answer be? Yes or no?
I know that if the uncertainty is really small then you can't blame the uncertainty principle but how small is too small?
I know that if the uncertainty is really small then you can't blame the uncertainty principle but how small is too small?
- Fri May 04, 2018 12:26 am
- Forum: Trends in The Periodic Table
- Topic: Electron affinity
- Replies: 4
- Views: 500
Re: Electron affinity
I believe that a full octet is the exception because once the shell is filled, the atom is stable and therefore there is no need for an electron to be added to the shell. For example, if you were asked which has a higher electron affinity between elements Ne and Cl, Cl would have the higher electron...
- Thu May 03, 2018 10:31 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Magnetic Quantum Number
- Replies: 2
- Views: 431
Re: Magnetic Quantum Number
I don't think we would be expected to find out the exact value of m(l). Instead, we would be asked to find the range, which is explained above. This range tells us how many orbitals there are. For example, if we are given l=2, we know that is a d orbital and have the values {-2,-1,0,1,2} which is 5 ...
- Thu May 03, 2018 10:26 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Clarification on Spin Quantum Number
- Replies: 4
- Views: 521
Re: Clarification on Spin Quantum Number
Spin quantum number is characterized by m(s) and the numbers +1/2 or -1/2. +1/2 is spin up and -1/2 is spin down but my TA said today that we won't need able to figure out which spin up or down it will be (nor will it really matter) without giving an extra bit of information that will be provided la...
- Thu Apr 26, 2018 9:35 pm
- Forum: Photoelectric Effect
- Topic: homework 1.25 part b
- Replies: 3
- Views: 383
Re: homework 1.25 part b
In order to solve problems and get the correct answer, you need to make sure you start with the correct units. Since they're asking for energy, you would need to be in atoms. Mg isn't the correct unit and therefore you would need to convert from mg to g to mol to atoms using dimensional analysis.
- Thu Apr 26, 2018 9:25 pm
- Forum: Properties of Light
- Topic: Rydberg Formula for Atomic Hydrogen [ENDORSED]
- Replies: 4
- Views: 958
Re: Rydberg Formula for Atomic Hydrogen [ENDORSED]
While the test will give you the E(n) = -(hR)/n^2, a faster equation that I was given in discussion that is very helpful is:
v (frequency) = R [(1/nf^2) - (1/ni^2)]
v (frequency) = R [(1/nf^2) - (1/ni^2)]
- Tue Apr 24, 2018 3:14 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra Post Module #29 [ENDORSED]
- Replies: 3
- Views: 542
Atomic Spectra Post Module #29 [ENDORSED]
The question states: In 1.0 s, a 60 W bulb emits 11 J of energy in the form of infrared radiation (heat) of wavelength 1850 nm. What is the energy per photon of light emitted? How many photons of infrared radiation does the lamp generate in 1.0 s? I figured out the energy per photon of light emitted...
- Tue Apr 17, 2018 9:13 pm
- Forum: Properties of Light
- Topic: 1.23
- Replies: 3
- Views: 399
Re: 1.23
Before you convert to joules, you also would need to convert from keV to eV before you do the joule conversion. This value is your energy (E) value. Because you are solving for wavelength, use the equation E = (h*c)/ lambda and solve for lambda (wavelength).
- Mon Apr 16, 2018 9:02 pm
- Forum: Properties of Light
- Topic: 1.13 (b)
- Replies: 6
- Views: 714
Re: 1.13 (b)
The table is in nanometers so your values should match the table once you convert from meters to nanometers.
- Mon Apr 16, 2018 6:08 pm
- Forum: Properties of Light
- Topic: still don't uderrsatnd what a photon is [ENDORSED]
- Replies: 20
- Views: 1453
Re: still don't uderrsatnd what a photon is [ENDORSED]
When you are changing energy levels (n), the difference in energy is given off as a photon when you are moving from a high energy electron to a lower energy level. This represents the principle of conversation of energy.
- Fri Apr 13, 2018 6:01 pm
- Forum: Empirical & Molecular Formulas
- Topic: Finding the molecular formula [ENDORSED]
- Replies: 5
- Views: 694
Re: Finding the molecular formula [ENDORSED]
Additionally, sometimes the empirical formula is the same as the molecular formula. All you need to do is calculate the molar mass of the empirical formula and compare with the given molar mass stated in the question. If the two numbers are the same, then your molecular formula is your empirical for...
- Fri Apr 13, 2018 5:57 pm
- Forum: Balancing Chemical Reactions
- Topic: H.15 adding solid, liquid, gas or aqueous to balanced equations [ENDORSED]
- Replies: 3
- Views: 616
Re: H.15 adding solid, liquid, gas or aqueous to balanced equations [ENDORSED]
Are we going to be required to add l, s, aq, or g at the end of these compounds? And how do they help us solve a problem?
- Thu Apr 12, 2018 12:27 am
- Forum: Molarity, Solutions, Dilutions
- Topic: When to use MiVi=MfVf
- Replies: 8
- Views: 4445
Re: When to use MiVi=MfVf
So it depends on what you're given. If you're given 2 different molarities and 1 volume and are asking for the other volume, use this equation. It also works if you're given 2 different volumes and 1 molarity and asked to find the molarity. You would use the equation M= moles/volume when you're only...
- Wed Apr 11, 2018 9:31 pm
- Forum: Limiting Reactant Calculations
- Topic: M.11
- Replies: 8
- Views: 1608
Re: M.11
How do you know that O2 is the limiting reactant for part a? After solving, I know that P4 is the limiting reactant for the first equation so do you use the leftover amount of O2 to find the limiting reactant for the second equation? Or do you use the 5.77 g O2 from the beginning to find the limitin...
- Wed Apr 11, 2018 8:51 pm
- Forum: Limiting Reactant Calculations
- Topic: M9
- Replies: 2
- Views: 273
M9
The question is: Copper nitrate reacts with sodium hydroxide to produce a precipitate of light blue copper hydroxide. In order to do this problem, I understand I need to find the balanced equation. When looking up the formula for those compounds, I get Cu(NO3)2 for copper nitrate, NaOH for sodium hy...
- Tue Apr 10, 2018 9:04 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: G.5 Part A) Molarity [ENDORSED]
- Replies: 9
- Views: 979
Re: G.5 Part A) Molarity [ENDORSED]
Also, why wouldn't you use the volume of 250 mL given in the first sentence of the question and use the equation M(initial)V(initial)=M(final)V(final)?