Search found 41 matches

by Chels Zh 1D
Mon Jul 31, 2017 11:14 pm
Forum: Lewis Acids & Bases
Topic: Electronegativity and Acid Strength
Replies: 1
Views: 239

Electronegativity and Acid Strength

As we know that HCl is a strong acid and because chlorine is high electronegativity, so that the higher electronegativity an ion is, the stronger its acid, why is this true?
by Chels Zh 1D
Mon Jul 31, 2017 10:02 pm
Forum: Lewis Acids & Bases
Topic: Acid and Base Strength
Replies: 1
Views: 185

Acid and Base Strength

What is the relationship between pKa and the acid strength, and the relationship between pKb and the basic strength?

I have trouble understanding this explanation in the answer-key book.

Thanks, someone who can help me explain it!! :))
by Chels Zh 1D
Sun Jul 30, 2017 11:07 pm
Forum: Conjugate Acids & Bases
Topic: Define conjugate acids & bases
Replies: 2
Views: 345

Re: Define conjugate acids & bases

For example, why Cl- is a conjugate base of HCl?
by Chels Zh 1D
Sun Jul 30, 2017 11:00 pm
Forum: Polyprotic Acids & Bases
Topic: Course Reader
Replies: 2
Views: 575

Re: Course Reader

I don't really understand the three equations of H2CO3+H2O in the end of this page, either.

What does it mean by," because harder to lose H+ from negatively charged ion(HCO3-)?"
by Chels Zh 1D
Sun Jul 30, 2017 10:52 pm
Forum: Identifying Acidic & Basic Salts
Topic: Salts
Replies: 3
Views: 473

Re: Salts

Generally speaking, salts are the products of acids and bases, an ionic compound composing of cation and anion.
by Chels Zh 1D
Sun Jul 30, 2017 10:50 pm
Forum: Amphoteric Compounds
Topic: Coursereader Pg 156
Replies: 1
Views: 198

Coursereader Pg 156

I am confused about the bold NOTE in the end of the course reader on page 156, saying that:
"if [H3O+] <10^-7, then solution is considered neutral because we know that autoprotolysis generates 10^-7 mol/L H3O+"
by Chels Zh 1D
Sun Jul 30, 2017 10:32 pm
Forum: Conjugate Acids & Bases
Topic: Define conjugate acids & bases
Replies: 2
Views: 345

Define conjugate acids & bases

Can someone please explain a base's conjugate acid and an acid's conjugate base to me? I am very confused with this relationship.
by Chels Zh 1D
Mon Jul 24, 2017 9:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Smart Chart
Replies: 1
Views: 294

VSEPR Smart Chart

Hi there, :) I found this VSEPR chart online, which seems pretty useful to me, hope this could help you guys too!

http://web.gccaz.edu/~kimld88531/vsepr%20handout.pdf
by Chels Zh 1D
Mon Jul 24, 2017 12:36 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Name of molecules shape
Replies: 1
Views: 183

Re: Name of molecules shape

It is Square Pyramidal.
by Chels Zh 1D
Sun Jul 23, 2017 10:15 pm
Forum: Lewis Structures
Topic: The position of Hydrogen in a Lewis structure
Replies: 1
Views: 313

The position of Hydrogen in a Lewis structure

Is it true that Hydrogen, H is always likely to attach to oxygen O atoms in a Lewis structure? :) For example, one homework problem from chapter 3. 57 (B), the Lewis structure of HSO3-, H restricts the electrons to the oxygen atom rather than to sulfur atom. Does it apply to all of the hydrogen atom...
by Chels Zh 1D
Sun Jul 23, 2017 3:42 pm
Forum: Ionic & Covalent Bonds
Topic: covalent bond
Replies: 7
Views: 534

covalent bond

Is it true that covalent bond only holds TWO nonmetal atoms together by sharing electrons?
by Chels Zh 1D
Sat Jul 22, 2017 9:14 pm
Forum: Formal Charge and Oxidation Numbers
Topic: hw ch3. 57
Replies: 1
Views: 239

hw ch3. 57

Reading the solution of Q57, for sulfite ion, SO3 2-, since both the structure followed the octet rule and the structure with expanded octet have the equal charge, what does it mean by "the structures with expanded octets have lower formal charges"?
by Chels Zh 1D
Sat Jul 22, 2017 4:59 pm
Forum: Lewis Structures
Topic: Formal Charge Relationship
Replies: 1
Views: 193

Formal Charge Relationship

What is the relationship between the sum of the formal charge of each atom in a covalent bond, and the charge of the compound itself? I found some practice shown that they are equal, is this a coincidence or it is the correct relationship. -:)
by Chels Zh 1D
Wed Jul 19, 2017 9:42 pm
Forum: Lewis Structures
Topic: Lewis dot position
Replies: 1
Views: 610

Lewis dot position

Does it matter where the dots are in a Lewis structure? For example, for Mg, both the textbook and course reader write it as Mg: , while when I looked it up online, it is written in a different way, like :Mg , does it matter where the dots are placed? Or is there a specific rule to follow when writi...
by Chels Zh 1D
Tue Jul 18, 2017 5:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Copper Ion Electron Configuration
Replies: 3
Views: 330

Copper Ion Electron Configuration

As I have been confused for a while, what is the correct electron configuration for Cu, and furthermore for its ion, Cu+, and Cu2+? Should we write it the way putting 4s ahead of 3d or not? I would highly appreciate someone if they may explain it.
by Chels Zh 1D
Thu Jul 13, 2017 10:31 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7582
Views: 1015191

Re: Post All Chemistry Jokes Here

954cb361299dbf962caaba2829ce6bd1--science-puns-chemistry-puns.jpg
954cb361299dbf962caaba2829ce6bd1--science-puns-chemistry-puns.jpg (10.42 KiB) Viewed 7185 times


Cation has positive charge
Cat has paws (^._.^)ノ
by Chels Zh 1D
Tue Jul 11, 2017 10:05 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: question on post module
Replies: 1
Views: 233

Re: question on post module

Hi, there, I happen to find a previous post that explained this question, see link below. Hope it helps!:)
viewtopic.php?t=5876
by Chels Zh 1D
Tue Jul 11, 2017 9:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: HW #2.51
Replies: 3
Views: 273

Re: HW #2.51

Nahal 1F wrote:How do you find the number of unpaired electrons for the ground state configuration of:

a)Pb
b)IR
c)Y
d)Cd


Man this is the question 52:))))))))
by Chels Zh 1D
Tue Jul 11, 2017 9:13 pm
Forum: Trends in The Periodic Table
Topic: Exercise 2.67
Replies: 4
Views: 376

Re: Exercise 2.67

I am still confused while I checked the chart in course reader page 70, it shows that carbon has an energy of +122kJ/mol, while nitrogen has an energy of -7kJ/mol. But why is it true according to the trend of electron affinity?
by Chels Zh 1D
Mon Jul 10, 2017 9:01 pm
Forum: Quantum Numbers and The H-Atom
Topic: HW Ch2. 19 (d)
Replies: 2
Views: 265

Re: HW Ch2. 19 (d)

sandraabdelmalak1D wrote:There are 3 subshells in the shell where n=3.
The number of types of subshells is the same as the shell number.
The first shell has one type of subshell (s)
The second shell has two types of subshells (s, p)
The third shell has three types of subshells (s, p, d).

Thanks!!
by Chels Zh 1D
Mon Jul 10, 2017 8:46 pm
Forum: Quantum Numbers and The H-Atom
Topic: HW Ch2. 19 (d)
Replies: 2
Views: 265

HW Ch2. 19 (d)

How many subshells are there in the shell with n=3?
How to solve problems like this? I looked up the answer but I don't know how to get it. Thanks!!! :)))
by Chels Zh 1D
Mon Jul 10, 2017 8:40 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: For Exam 1
Replies: 4
Views: 528

Re: For Exam 1

Thanks, guys! :)))
by Chels Zh 1D
Mon Jul 10, 2017 7:13 pm
Forum: Empirical & Molecular Formulas
Topic: Limiting Reactants?
Replies: 5
Views: 801

Re: Limiting Reactants?

For step (a), I would like to go with to assume there are 100g of the sample, I got the ratio is 4:4:1 of C:O:Os. Then I got the empirical formula OsC4O4. Then at (b) we can calculate the molar mass of the empirical formula, which is 302.24 g/mol, divided this number by 907 g/mol, which gives us a n...
by Chels Zh 1D
Mon Jul 10, 2017 6:42 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: For Exam 1
Replies: 4
Views: 528

For Exam 1

Does someone know that from which page to which page in the course reader is covered in Exam 1 on Wednesday?
by Chels Zh 1D
Wed Jul 05, 2017 11:37 pm
Forum: Student Social/Study Group
Topic: Self Test 1 Answers
Replies: 8
Views: 808

Re: Self Test 1 Answers

Hey guys, how did you get no.5, I got an extremely small number, I think I might have got some steps wrong.
by Chels Zh 1D
Wed Jul 05, 2017 9:33 pm
Forum: Limiting Reactant Calculations
Topic: help with question
Replies: 2
Views: 488

Re: help with question

[attachment=0]IMG_0432.JPG[/attachment]
by Chels Zh 1D
Wed Jul 05, 2017 8:18 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation - Course Reader
Replies: 2
Views: 339

Re: De Broglie Equation - Course Reader

I believe the mass of an electron is a constant that we don't need to calculate, and I think it will be provided for us in the test.
by Chels Zh 1D
Wed Jul 05, 2017 8:15 pm
Forum: DeBroglie Equation
Topic: self test 1: #3 part b
Replies: 3
Views: 296

Re: self test 1: #3 part b

Hi, there, here is what I got
IMG_0428.JPG


And thanks for telling me where the self-test is!
Hope this would help!
by Chels Zh 1D
Wed Jul 05, 2017 4:04 pm
Forum: Properties of Light
Topic: Unable to attend TA's review section today (7/5/17)
Replies: 1
Views: 179

Re: Unable to attend TA's review section today (7/5/17)

Same... I have calculus lecture colliding with today's review section.
by Chels Zh 1D
Wed Jul 05, 2017 4:03 pm
Forum: DeBroglie Equation
Topic: self test 1: #3 part b
Replies: 3
Views: 296

Re: self test 1: #3 part b

Could you type the full question please, and by the way, where can I find the self-test?
by Chels Zh 1D
Tue Jul 04, 2017 12:12 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: True Or False??
Replies: 2
Views: 344

True Or False??

The energy of an atom is increased when electromagnetic radiation is emitted from it?
by Chels Zh 1D
Mon Jul 03, 2017 7:31 pm
Forum: Photoelectric Effect
Topic: role of wavelength
Replies: 2
Views: 253

Re: role of wavelength

Thank you so much!!!!!!!! I understand it clearly now.
by Chels Zh 1D
Mon Jul 03, 2017 7:01 pm
Forum: Photoelectric Effect
Topic: role of wavelength
Replies: 2
Views: 253

role of wavelength

When I was going through the summary part of the photoelectric experiment, I have a couple of unclear concepts.
The first point said that "light not acting like a classical wave", so what role does it act? As photons or particles?
Does high intensity mean the light beam with more photons?
by Chels Zh 1D
Sun Jul 02, 2017 7:13 pm
Forum: Photoelectric Effect
Topic: Question from the online post assessments
Replies: 4
Views: 390

Re: Question from the online post assessments

[quote="Gwyndolyn"]The formula sheet gives the mass of an electron as 9.1095 x 10^-31 kg, so I think you would just use this.[/quote]


Thanks! I greatly appreciate that :)
by Chels Zh 1D
Sun Jul 02, 2017 5:45 pm
Forum: Photoelectric Effect
Topic: Question from the online post assessments
Replies: 4
Views: 390

Re: Question from the online post assessments

Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. Answer the following three questions. A. What is the kinetic energy of the ejected electron? For this question, we should use the equation of kinetic energy...
by Chels Zh 1D
Sun Jul 02, 2017 5:32 pm
Forum: Photoelectric Effect
Topic: Question from the online post assessments
Replies: 4
Views: 390

Question from the online post assessments

When the energy per photon is equal to the energy required to remove an electron what is this energy called?
A. Binding energy

B. Threshold energy

C. Transition energy

D. Excitation energy
My answer is A. Binding energy, but it showed me wrong, what is the correct answer?
by Chels Zh 1D
Sun Jul 02, 2017 12:08 pm
Forum: SI Units, Unit Conversions
Topic: Dimensional Analysis/ Unit conversion [ENDORSED]
Replies: 5
Views: 571

Re: Dimensional Analysis/ Unit conversion [ENDORSED]

Hi there, it's not a problem of using whether one giant step or breaking up into small parts, I feel like it is just personal preferences, for me, I like to classify the same type together on the same side, getting easier to visualize. And for instance, it is always useful to use the SI units as the...
by Chels Zh 1D
Sat Jul 01, 2017 10:37 pm
Forum: Properties of Light
Topic: Lecture 3 blackbody's emit spectrum
Replies: 3
Views: 247

Re: Lecture 3 blackbody's emit spectrum

Question extension:
What does a blackbody specifically mean in the speaking of photons and spectrum?
Does it apply to any light source or it just implies to the sun, which Dr. Lavelle mentioned in class?
by Chels Zh 1D
Sat Jul 01, 2017 10:25 pm
Forum: Properties of Light
Topic: Exercise 1.15 (Ch 1 : The Quantum World)
Replies: 4
Views: 349

Re: Exercise 1.15 (Ch 1 : The Quantum World)

Hi there, just got a quick thought of what you may concern: I will follow up the steps next, since you've already got to 0.1112, which is the frequency we need for n1, and by using Rydberg equation we can solve for n2: v=R(1/n1^2-1/n2^2), from that equation, we have known that constant R = 3.29E15, ...
by Chels Zh 1D
Sat Jul 01, 2017 9:50 pm
Forum: Balancing Chemical Reactions
Topic: Order of molecules balanced
Replies: 6
Views: 602

Re: Order of molecules balanced

From my experience of balancing equations, I always adjust the metals first, nonmetals last. Because metals are usually the kinds of elements has the least amount of atoms, existing in a formula unit, compounding with other nonmetals. Like the previous person said, I like to leave H & O at the v...

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