Search found 20 matches

by Matthew Leung 1B
Tue Aug 01, 2017 3:36 pm
Forum: Identifying Acidic & Basic Salts
Topic: Anions as acids
Replies: 2
Views: 334

Re: Anions as acids

So is this due to the electronegativity of Oxygen? In general, can I use the electronegativity to determine whether a H+ will be given off?
by Matthew Leung 1B
Mon Jul 31, 2017 5:46 pm
Forum: Polyprotic Acids & Bases
Topic: Course Reader
Replies: 2
Views: 573

Re: Course Reader

Same here! Also, is it true that Ka1 > Ka2 > Ka3 implies that H2CO3 has less acidity than HCO3- ? If so, why would this be true?
by Matthew Leung 1B
Mon Jul 31, 2017 3:58 pm
Forum: General Science Questions
Topic: Polyatomic ions
Replies: 1
Views: 438

Polyatomic ions

Does anyone know if there is any way to find the charge of polyatomic ions other than memorization? Is there a lost of polyatomic ions that we should know specifically for this class?
by Matthew Leung 1B
Mon Jul 31, 2017 3:54 pm
Forum: Identifying Acidic & Basic Salts
Topic: Anions as acids
Replies: 2
Views: 334

Anions as acids

The book mentioned that very few anions act as acids as its more difficult for an anion to lose H+. Why would HSO4 and H2PO4- be exceptions?
by Matthew Leung 1B
Sun Jul 30, 2017 11:59 pm
Forum: Dipole Moments
Topic: Water molecule and dipole moments
Replies: 2
Views: 2490

Re: Water molecule and dipole moments

Thanks, so detailed.
by Matthew Leung 1B
Sat Jul 29, 2017 6:20 pm
Forum: Lewis Acids & Bases
Topic: Self test 12.2B
Replies: 2
Views: 198

Re: Self test 12.2B

I see, this is really helpful! Thanks!
by Matthew Leung 1B
Sat Jul 29, 2017 3:36 pm
Forum: Lewis Acids & Bases
Topic: Self test 12.2B
Replies: 2
Views: 198

Self test 12.2B

For the reaction HCO3- + NH4+ ⇌ H2CO3 + NH3, according to the answer key, the Lewis acid is H+. Why would this be the case instead of NH4+ and H2CO3 being the Lewis acids? Thanks!
by Matthew Leung 1B
Mon Jul 24, 2017 4:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Self test 11.7B
Replies: 1
Views: 161

Self test 11.7B

A mixture of N2O4 and NO2 with initial partial pressure of 2.4 and 1.2 bar was prepared. Which compound will tend to increase it's partial pressure?
I know that Q = 0.6 > K (=0.15), but which compound will increase it's partial pressure and why? Thanks!
by Matthew Leung 1B
Sun Jul 23, 2017 11:54 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarization Power vs. Polarizability
Replies: 1
Views: 330

Re: Polarization Power vs. Polarizability

Yes you are right. To my knowledge, a cation or an atom that exerts strong electrostatic attraction has high polarizing power, whereas the anion or atom that is acted on is said to be highly polarizable.
by Matthew Leung 1B
Sun Jul 23, 2017 11:46 pm
Forum: Dipole Moments
Topic: Water molecule and dipole moments
Replies: 2
Views: 2490

Water molecule and dipole moments

Cam someone please explain why H2O is bent and how is this related to the dipole moments (i.e., why is it polar)?
by Matthew Leung 1B
Sun Jul 23, 2017 11:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Course grade break down
Replies: 3
Views: 425

Re: Course grade break down

I think it's one point per post. Also, does anyone know how grades are assigned? The syllabus states that it's based on the class average, so is 93% a guaranteed A?
by Matthew Leung 1B
Sun Jul 23, 2017 6:49 pm
Forum: Administrative Questions and Class Announcements
Topic: Course grade break down
Replies: 3
Views: 425

Course grade break down

Hi, I remember that professor Lavelle told us that we can get a total of 20 points for posting here. That being said, is the total still 350 points? Thanks!
by Matthew Leung 1B
Sun Jul 09, 2017 11:44 pm
Forum: Photoelectric Effect
Topic: Example 1.5
Replies: 3
Views: 392

Re: Example 1.5

Yes they are equivalent to my knowledge!
by Matthew Leung 1B
Wed Jul 05, 2017 5:39 pm
Forum: Properties of Light
Topic: Homework 1.21
Replies: 1
Views: 224

Homework 1.21

Question: from the following list of observations, select one that best supports the idea that electromagnetic radiation has the properties of particles. Black-body radiation, electron diffraction, atomic spectra, and photoelectric effect. I understand that photoelectric effect gave rise to the conc...
by Matthew Leung 1B
Wed Jul 05, 2017 5:15 pm
Forum: General Science Questions
Topic: Question about course reader
Replies: 1
Views: 418

Re: Question about course reader

I believe page 176 has most constants and formulas we need!
by Matthew Leung 1B
Tue Jul 04, 2017 2:57 pm
Forum: Photoelectric Effect
Topic: Example 1.5
Replies: 3
Views: 392

Example 1.5

Just want to make sure that I didn't make wrong calculations for part B. At the bottom of that page, the last step was finding the wavelength by 3.00*10^8 / (5.7*10^-19 / 6.626*10^-34). I got 3.49 * 10^-7 m as opposed to 3.49 * 10^-17 m as stated in the textbook, can anyone help verify this? Thanks!
by Matthew Leung 1B
Sun Jul 02, 2017 11:28 pm
Forum: Balancing Chemical Reactions
Topic: Fundamentals H 13
Replies: 1
Views: 334

Fundamentals H 13

The question described the case where nitrogen and oxygen gases react in the hot exhaust environment of an automobile engine, where nitric oxide gas is formed. I am not sure whether nitrogen and oxygen is diatomic only in room temperature or also in higher temperature. Can anyone help clarify that? ...
by Matthew Leung 1B
Sun Jul 02, 2017 9:46 pm
Forum: Student Social/Study Group
Topic: Exams/tests ?
Replies: 4
Views: 425

Re: Exams/tests ?

According to my TA, the format of the tests are like our assigned homework problems. But I think we can have professor Lavelle clarify on that, like how many questions are there.
by Matthew Leung 1B
Sun Jul 02, 2017 2:48 pm
Forum: Molarity, Solutions, Dilutions
Topic: homework G5
Replies: 6
Views: 510

Re: homework G5

In this question, the formula for sodium carbonate was not given, does anyone know if we have to write the formulas by ourselves in the test? Thanks!
by Matthew Leung 1B
Fri Jun 30, 2017 9:10 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamentals E.17
Replies: 4
Views: 600

Re: Fundamentals E.17

1 mole of objects means 6.0221 * 10^23 of those objects, in this case, 7.36 * 10^27 atoms of Ru and 7.36 * 10^27 atoms of Fe contain the same number of moles: 7.36 * 10^27 / 6.0221 * 10^23 = 0.0122 * 10^6 hope this helps:)

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