Search found 56 matches

by A Raab 1K
Thu Dec 05, 2019 7:08 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Question on homework 6.13
Replies: 1
Views: 43

Re: Question on homework 6.13

Exactly! There isn't any resonance for this structure, so resonance is not important for its description.
by A Raab 1K
Thu Dec 05, 2019 7:07 pm
Forum: Electronegativity
Topic: Ion Size
Replies: 2
Views: 113

Ion Size

Is Mg+2 bigger or smaller than Na+?
Is O-2 bigger or smaller than N-3?
Arrange the anions Cl- , Br- , N-3, and O-2 in order of increasing polarizability and give reasons for your decisions.
Thanks!
by A Raab 1K
Mon Dec 02, 2019 10:00 pm
Forum: Conjugate Acids & Bases
Topic: 6A.9
Replies: 2
Views: 38

Re: 6A.9

NH4I is a salt, so there isn't a conjugate acid or base. You can find which acids or bases it is derived from though, which is NH4+ and I -
by A Raab 1K
Mon Dec 02, 2019 9:44 pm
Forum: Identifying Acidic & Basic Salts
Topic: HW 6D11
Replies: 7
Views: 113

HW 6D11

Decide whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7. If pH . 7 or pH , 7, write a chemical equation to justify your answer. (e) AlCl3; (f) Cu(NO3)2 For e and f, how do you get the equations that are given in the answer key? e. Al(H2O)6 +3...
by A Raab 1K
Mon Dec 02, 2019 5:23 pm
Forum: Lewis Acids & Bases
Topic: HW Question J23
Replies: 1
Views: 39

HW Question J23

The oxides of nonmetallic elements are called acidic oxides because they form acidic solutions in water. Write the balanced chemical equations for the reaction of 1 mol of formula units of each acidic oxide with 1 mol of water molecules to form an oxoacid and name the acid formed: (a) CO2 b) SO3 How...
by A Raab 1K
Fri Nov 29, 2019 1:05 pm
Forum: Bronsted Acids & Bases
Topic: 6D11
Replies: 1
Views: 45

6D11

6D.11 Decide whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7. If pH . 7 or pH , 7, write a chemical equation to justify your answer. (a) NH4Br; (b) Na2CO3; (c) KF; (d) KBr; (e) AlCl3; (f) Cu(NO3)2 For part d, why is KBr neutral? Can't you wr...
by A Raab 1K
Thu Nov 28, 2019 3:48 pm
Forum: Bronsted Acids & Bases
Topic: Writing Equations
Replies: 1
Views: 28

Writing Equations

How do you know when to write an equation with the arrow pointing one way versus the set of arrows pointing both ways?
by A Raab 1K
Thu Nov 28, 2019 3:39 pm
Forum: Bronsted Acids & Bases
Topic: J17 Help
Replies: 2
Views: 56

Re: J17 Help

How do you know the Cl goes with O instead of with K? (part b)
by A Raab 1K
Thu Nov 28, 2019 12:31 pm
Forum: Bronsted Acids & Bases
Topic: Acid vs Base
Replies: 4
Views: 64

Acid vs Base

How do you tell the difference between a Bronsted acid and base? For example, in J1, it asks you to identify (a) NH 3 ; (b) HBr; (c) KOH; (d) H 2 SO 3 ; (e) Ca(OH) 2 I understand that for c and e, there's an OH in the compound which leads one to believe it's a base. Is this line of thinking correct?...
by A Raab 1K
Mon Nov 25, 2019 10:47 pm
Forum: Naming
Topic: ... the dang 9C toolbox LOL
Replies: 3
Views: 36

Re: ... the dang 9C toolbox LOL

So because NH3 and H2O both have no charge, the charge of Fe has to be +3 in order for the charge of the whole molecule to also be +3. You find the charge of the metal that fits with the overall charge of the molecule.
by A Raab 1K
Mon Nov 25, 2019 10:42 pm
Forum: Naming
Topic: 9C3d
Replies: 4
Views: 75

9C3d

Write: sodium bisoxalato(diaqua)ferrate(III)
Does it make a difference whether I write (OH2) versus just (H2O)?
For example, why is it Na[Fe(OH2)2(C2O4)2], and not Na[Fe(H2O)2(C2O4)2] or Na[Fe(C2O4)2(H2O)2]?
by A Raab 1K
Mon Nov 25, 2019 7:11 pm
Forum: Naming
Topic: -ate ending
Replies: 8
Views: 81

Re: -ate ending

If the complex is negatively charged, then you add -ate to the end of the metal name.
by A Raab 1K
Mon Nov 18, 2019 7:55 pm
Forum: Lewis Structures
Topic: radicals
Replies: 3
Views: 62

Re: radicals

Radicals have an uneven number of electrons.
Do you mean the single electron instead of unpaired electron for the second question?
by A Raab 1K
Mon Nov 18, 2019 7:51 pm
Forum: Hybridization
Topic: 2F.5 Homework
Replies: 1
Views: 35

Re: 2F.5 Homework

For each one, you would draw the Lewis structure and see the regions of electron density on each central atom. Then, in accordance with how many regions there are, you can assign the hybridization. For example, BeCl2 has 2 bonds from Be to Cl, so the hybridization would be sp.
by A Raab 1K
Mon Nov 18, 2019 7:48 pm
Forum: Lewis Structures
Topic: double and triple bonds
Replies: 6
Views: 103

Re: double and triple bonds

AsF3 would not have any double bonds. Instead, there should be a single bond from As to F, with each F having three lone pairs and As having one lone pair. This adds up to 26 electrons and they all have a formal charge of 0, as As has 5 valence electrons, which the 3 bonds and 2 lone electrons satis...
by A Raab 1K
Mon Nov 18, 2019 5:18 pm
Forum: Sigma & Pi Bonds
Topic: HW Question 2.63
Replies: 1
Views: 41

HW Question 2.63

2.63 Estimate the bond angles marked with arcs and lowercase letters in peroxyacetylnitrate, an eye irritant in smog. Sorry I'm not sure how to put an image in here from the problem in the textbook but there are 3 angles we have to estimate. I understand a and c, but for part b, why is the bond angl...
by A Raab 1K
Mon Nov 18, 2019 12:49 pm
Forum: Hybridization
Topic: HW Question 2F15
Replies: 1
Views: 38

HW Question 2F15

Noting that the bond angle of an sp 3 hybridized atom is 109.5 and that of an sp 2 hybridized atom is 120, do you expect the bond angle between two hybrid orbitals to increase or decrease as the s-character of the hybrids is increased?
Can anyone explain why the bond angle increases?
by A Raab 1K
Tue Nov 12, 2019 5:33 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: HW Question 3F19
Replies: 2
Views: 43

Re: HW Question 3F19

I'm still not quite sure how vapor pressure relates to the different intermolecular forces there are.
by A Raab 1K
Tue Nov 12, 2019 5:30 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths in molecules
Replies: 7
Views: 71

Re: Bond lengths in molecules

Bond lengths are the length of the bond between two atoms. Bond length has to do with a number of factors, one of them being the size of the atom. An example was given in class of the bond lengths between HF, HCl, HBr, and HI. The bond lengths between those molecules get progressively longer as the ...
by A Raab 1K
Tue Nov 12, 2019 5:26 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 7
Views: 159

Re: Formal Charge

Formal charge = V - (L - S/2)
V is valence electrons of the element
L is lone pairs the atom has
S is shared/bonding electrons
You want a formal charge of 0 on an atom as that is the most stable.
by A Raab 1K
Tue Nov 12, 2019 5:11 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: HW Question 3F19
Replies: 2
Views: 43

HW Question 3F19

Account for the following observations in terms of the type and strength of intermolecular forces. (b) The vapor pressure of diethyl ether (C2H5OC2H5) is greater than that of water. (c) The boiling point of pentane, CH3(CH2)3CH3, is 36.1 C, whereas that of 2,2-dimethylpropane (also known as neopenta...
by A Raab 1K
Tue Nov 12, 2019 5:08 pm
Forum: Dipole Moments
Topic: 3F.3
Replies: 5
Views: 80

Re: 3F.3

I looked at the fact that b, c, and d were all uneven whereas a and e were even. This unevenness is due to the differing number of electrons on the hydrogen versus the chlorine.
by A Raab 1K
Tue Nov 12, 2019 12:05 pm
Forum: Dipole Moments
Topic: HW Question 3F1
Replies: 5
Views: 72

HW Question 3F1

Why does (part d) SO2 have a dipole-dipole interaction?
by A Raab 1K
Tue Nov 05, 2019 10:45 pm
Forum: SI Units, Unit Conversions
Topic: HELP WITH UNITS
Replies: 6
Views: 274

Re: HELP WITH UNITS

It doesn't matter! It's probably better to convert to SI units so that when you plug numbers into equations, the equations work correctly, but for the final answer it doesn't matter if it's in (for example) km or m.
by A Raab 1K
Tue Nov 05, 2019 10:43 pm
Forum: Lewis Structures
Topic: HW Question 2C5
Replies: 2
Views: 68

HW Question 2C5

For a, draw the Lewis structure of (a) chlorine monoxide, ClO I drew the molecule as .. .. O=Cl . .. .. Why isn't this correct? The correct answer according to the answer key is .. .. :O - Cl . .. .. but I don't understand how this is correct, because the formal charges are not 0 for this answer, bu...
by A Raab 1K
Mon Nov 04, 2019 11:10 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook E13
Replies: 1
Views: 127

Re: Textbook E13

That wasn't a question that ever appeared on the homework so I don't think you have to worry about it!
by A Raab 1K
Mon Nov 04, 2019 11:08 pm
Forum: SI Units, Unit Conversions
Topic: Formula Units
Replies: 2
Views: 127

Re: Formula Units

You would usually use 6.022 * 10^23 to figure out the number of formula units. For example, the number of formula units in 1 mole of some atom is 6.022 * 10^23. It's pretty universal and can be used to find, for example, the number of molecules in 1 mole as well.
by A Raab 1K
Mon Nov 04, 2019 11:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Class Wed 11/6
Replies: 3
Views: 48

Class Wed 11/6

Do we have lecture on Wednesday? I heard some people say we didn't but Lavelle didn't say anything in class about it. I'm in the 10:00 lecture by the way.
by A Raab 1K
Thu Oct 31, 2019 3:42 pm
Forum: Ionic & Covalent Bonds
Topic: 2A 1
Replies: 5
Views: 55

Re: 2A 1

The electron configuration for Sb is [Kr] 4D10 5S2 5P3. If you count the electrons in the highest level (5) then you can see that there's 5 valence electrons.
by A Raab 1K
Thu Oct 31, 2019 3:33 pm
Forum: *Shrodinger Equation
Topic: shrodinger equation
Replies: 4
Views: 78

Re: shrodinger equation

I think it just describes the wave function or a path that a given system will take. It has to do with potential energy and kinetic energy to find the total energy, and using it to find the behavior of an electron bound to a nucleus.
by A Raab 1K
Mon Oct 28, 2019 3:57 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HW Question 2A5
Replies: 3
Views: 61

HW Question 2A5

Give the ground-state electron configuration expected for each of the following ions: (a) Cu +1; (b) Bi +3 ; (c) Ga +3 ; (d) Tl +3 . For a, why is the answer [Ar] 3d10, instead of [Ar] 3d8 4s2? I understand for Cu normally the notation would be 3d10, but that's when the d orbital is at 9, not at 8, ...
by A Raab 1K
Mon Oct 28, 2019 2:41 pm
Forum: Resonance Structures
Topic: Resonance vs. Resonance Hybrid
Replies: 2
Views: 47

Re: Resonance vs. Resonance Hybrid

They are the same thing. Resonance structures show how the same molecule can be drawn different ways depending on what orientation you draw the different bonds, whereas resonance hybrids is just another term to emphasis the actual structure of molecules, which is that the bonds all have the same len...
by A Raab 1K
Mon Oct 28, 2019 2:34 pm
Forum: Resonance Structures
Topic: HW Question 2B9
Replies: 3
Views: 38

Re: HW Question 2B9

Let me know if the question is confusing, and I can try to rephrase!
by A Raab 1K
Mon Oct 28, 2019 2:33 pm
Forum: Resonance Structures
Topic: HW Question 2B9
Replies: 3
Views: 38

HW Question 2B9

2B9. Draw the complete Lewis structure for each of the following compounds: (a) ammonium chloride; (b) potassium phosphide; (c) sodium hypochlorite How come for these structures you draw the elements separately? For example in part b, the answer key shows K+ around a P -3 instead of lines connecting...
by A Raab 1K
Wed Oct 23, 2019 12:35 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 13
Views: 346

Re: Electron Configurations

To add on the information already provided, the order goes s, p, d, f. For s, there's a maximum of 2 electrons; for p there's 6; for d there's 10 and for f there's 14. Hope that helps when you write it out.
by A Raab 1K
Wed Oct 23, 2019 12:29 am
Forum: DeBroglie Equation
Topic: 1B.9 HW Question
Replies: 8
Views: 121

Re: 1B.9 HW Question

Yes exactly! 64 J is the energy expended over 2 seconds (2 * 32)
by A Raab 1K
Tue Oct 22, 2019 10:53 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: s, p, d, f orbitals
Replies: 15
Views: 165

Re: s, p, d, f orbitals

The 4s orbital has more energy than the 3d orbital. However, for elements like potassium and calcium, the 3d orbitals have a higher energy than the 4s, as the 4s levels fill before than the 3d. But for the next 10 elements of the transition series, the 3d orbitals gradually fill with electrons, and ...
by A Raab 1K
Tue Oct 22, 2019 10:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Questions
Replies: 2
Views: 55

Re: Midterm Questions

I'm not sure, but the midterm is 2 hours long, so however many questions can be done in that time. You can try asking your TA!
by A Raab 1K
Tue Oct 22, 2019 10:36 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HW Question 1E5 d
Replies: 1
Views: 46

HW Question 1E5 d

d. Zeffe for an electron in a p-orbital is lower than for an electron in an s - orbital in the same shell
What does Zeffe represent? And why is this true?
by A Raab 1K
Tue Oct 15, 2019 2:34 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: EM radiation
Replies: 3
Views: 154

EM radiation

How do we know what wavelengths correspond to which types of electromagnetic radiation? Do we have to know them for the tests or will they be given to us?
For ex, when a question asks what electromagnetic radiation has a wavelength of 8.84 nm?
by A Raab 1K
Tue Oct 15, 2019 1:13 pm
Forum: DeBroglie Equation
Topic: 1B.5
Replies: 3
Views: 68

Re: 1B.5

I just looked up what keV was, so hopefully we don't have to know that for tests (maybe it'll be provided?)
1 keV = 1.60217662e-16 joules
by A Raab 1K
Tue Oct 15, 2019 12:47 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Light's effects
Replies: 4
Views: 50

Re: Light's effects

The way it was described in class was that the size of a baseball is much larger than the size of an electron, and therefore an electron can be affected by photons whereas a baseball is much too big to be noticeably affected. Light affects an electron because photons can hit the electrons passing th...
by A Raab 1K
Tue Oct 15, 2019 12:41 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Momentum
Replies: 7
Views: 130

Re: Momentum

Momentum is the mass of an object times velocity, or p = m * v. So yes, we might have to solve for momentum for Heisenberg's equation.
by A Raab 1K
Tue Oct 15, 2019 12:45 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: HW Problem 1.A.15
Replies: 3
Views: 62

HW Problem 1.A.15

1.A.15 In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. I was trying to use the Rydberg formula for this problem, so I trie...
by A Raab 1K
Thu Oct 10, 2019 2:55 pm
Forum: SI Units, Unit Conversions
Topic: Course Reader
Replies: 6
Views: 151

Re: Course Reader

There isn't a course reader for Lavelle's class.
by A Raab 1K
Thu Oct 10, 2019 2:52 pm
Forum: Student Social/Study Group
Topic: readings
Replies: 13
Views: 231

Re: readings

I don't think there's any readings that you are required to do. You can read the textbook that correspond to the lectures in class if you want to.
by A Raab 1K
Thu Oct 10, 2019 2:50 pm
Forum: Significant Figures
Topic: Sig Figs only for Decimal Points vs for all integers in the Answer
Replies: 5
Views: 89

Re: Sig Figs only for Decimal Points vs for all integers in the Answer

I'm pretty sure that you always go to the lowest number of sigfigs of a number that's present in a problem.
by A Raab 1K
Tue Oct 08, 2019 5:40 pm
Forum: Empirical & Molecular Formulas
Topic: Formula Units
Replies: 10
Views: 147

Re: Formula Units

A formula unit can be an atom, compound, or molecule. For example, if a question asks how many formula units of H2O are in one mole of H2O, then you would just find the number of atoms in one mole of H2O.
by A Raab 1K
Tue Oct 08, 2019 3:47 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Conserved in Chem Rxn
Replies: 5
Views: 207

Conserved in Chem Rxn

Which of the following are conserved in a chemical reaction? Select all that apply.
a. mass
b. number of atoms
c. number of molecules
d. number of electrons
e. number of protons

I think a and b are conserved, but I'm not sure if d and e are also conserved. Can anyone confirm?
by A Raab 1K
Mon Oct 07, 2019 5:21 pm
Forum: Properties of Light
Topic: Problem 1A.3c
Replies: 2
Views: 60

Problem 1A.3c

Which of the following happens when the frequency of electromagnetic radiation decreases? Explain your reasoning. (c) The extent of the change in the electrical field at a given point decreases I'm not sure what exactly "c" means by the change in the electrical field at a given point. Can ...
by A Raab 1K
Tue Oct 01, 2019 9:23 pm
Forum: Balancing Chemical Reactions
Topic: Question H7a
Replies: 6
Views: 70

Re: Question H7a

Along that same theme, how would I know what to do for metal solids such as magnesium or for a nitrogen atmosphere? Magnesium is just Mg, whereas the nitrogen atmosphere is N2.
by A Raab 1K
Tue Oct 01, 2019 8:43 pm
Forum: Balancing Chemical Reactions
Topic: Question H7a
Replies: 6
Views: 70

Question H7a

H7a. Write a balanced chemical equation for each of the following reactions. (a) Calcium metal reacts with water to produce hydrogen gas and aqueous calcium hydroxide.
For calcium hydroxide, how would one know if the molecule is CaOH or Ca(OH)2? (and for other molecules that include hydroxide too)
by A Raab 1K
Tue Oct 01, 2019 7:34 pm
Forum: Limiting Reactant Calculations
Topic: Problem G5
Replies: 2
Views: 77

Problem G5

G5. A student prepared a solution of sodium carbonate by adding 2.111 g of the solid to a 250.0-mL volumetric flask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a flask to obtain (a) 2.15 mmol Na1; (b) 4.98 m...
by A Raab 1K
Tue Oct 01, 2019 7:14 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Question on E17c
Replies: 2
Views: 48

Re: Question on E17c

You're actually correct! Since the question gave you the same number of atoms, that means that the moles of atoms would also be the same.
by A Raab 1K
Tue Oct 01, 2019 7:09 pm
Forum: Empirical & Molecular Formulas
Topic: E.25 Parts (b) & (c)
Replies: 2
Views: 45

Re: E.25 Parts (b) & (c)

For b: The molar mass of Ag2SO4 is 2(107.87) + 32.06 + 4(15.999) = 311.80 g/mol Then, multiply 311.80 g/mol * (2.39*10^23)/(6.022*10^23) = 123.75 mg which is about 124 mg For c: The molar mass of 22.99 + 1.008 + 12.011 + 2(15.999) = 68.007 g/mol Divide 3.429 g / 68.007g/mol = 0.05 mol Multiply 0.05 ...
by A Raab 1K
Mon Sep 30, 2019 8:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 150
Views: 10349

Re: Advice from a Medical Student - Part II [ENDORSED]

I've heard that if you can imagine yourself being anything else besides a doctor, than the medical route may not be the right path for you. Do you think there's any truth to that statement; does medicine really need to be a calling in order to succeed? I'm on the fence about different career options...

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