Search found 26 matches

by Michelle Pham_3H
Sun Dec 10, 2017 10:27 am
Forum: Administrative Questions and Class Announcements
Topic: Practice Test Fall 2017 [ENDORSED]
Replies: 19
Views: 2088

Re: Practice Test Fall 2017 [ENDORSED]

The moles of iodine is in a solid state, so it wouldn't be included when determining which side has more moles of gas.
by Michelle Pham_3H
Sat Dec 09, 2017 2:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium True/False
Replies: 2
Views: 419

Re: Chemical Equilibrium True/False

Hi! During last night's review session, there was a True/False question that stated "For a given reaction, changing temperature is the only way to change K" (#41). The answer was true. If you lower the activation energy, does that in turn change the temperature of the system? I'm just a bi...
by Michelle Pham_3H
Tue Dec 05, 2017 8:41 pm
Forum: Lewis Acids & Bases
Topic: Lewis v. Bronsted Acids/Bases
Replies: 2
Views: 245

Re: Lewis v. Bronsted Acids/Bases

This is really helpful, thank you!!
by Michelle Pham_3H
Mon Dec 04, 2017 11:32 pm
Forum: Lewis Acids & Bases
Topic: Lewis v. Bronsted Acids/Bases
Replies: 2
Views: 245

Lewis v. Bronsted Acids/Bases

I understand that these terms have different and complimentary definitions, but is there any easy way to remember which is which? I keep mixing them up and it would be nice to have a mnemonic device or something to distinguish them from each other. Thanks in advance! Lewis acid = electron acceptor L...
by Michelle Pham_3H
Mon Dec 04, 2017 11:24 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Comparing Strengths of acid from structure/formula
Replies: 1
Views: 149

Re: Comparing Strengths of acid from structure/formula

Increasing the amount of oxygen atoms also increases the oxidation state and the electronegativity of the compound. The oxygen atoms pull electron density towards themselves, weakening the O-H bonds. This makes it easier for the H+ to ionize in water, making the acid stronger. Overall, adding oxygen...
by Michelle Pham_3H
Tue Nov 28, 2017 1:07 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q [ENDORSED]
Replies: 7
Views: 518

Re: Q [ENDORSED]

To add on to what was said earlier, Q is the ratio of the products to reactants in a given instant, while K is this ratio at equilibrium.
by Michelle Pham_3H
Tue Nov 28, 2017 12:59 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Concept Question
Replies: 3
Views: 221

Concept Question

Today in lecture, we discussed a lot of conceptual ideas regarding the response of equilibria to change and Le Chatelier's principle. Professor asked a question that I didn't catch the answer to. If someone could explain and answer this question I would really appreciate it: Without adding more reac...
by Michelle Pham_3H
Wed Nov 22, 2017 6:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Gas concentration
Replies: 2
Views: 123

Re: Gas concentration

The concentration is equal to n/v since it is moles of substance over its volume. So when you rearrange the equation from PV = nRT, n/V = P/RT. n is the moles of gas, V is the volume of gas, P is is the pressure of the gas, R is the gas constant, and T is the absolute temperature of the gas.
by Michelle Pham_3H
Wed Nov 22, 2017 6:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium Composition [ENDORSED]
Replies: 2
Views: 141

Calculating Equilibrium Composition [ENDORSED]

Today in lecture we discussed how one would calculate equilibrium concentrations using x in the ICE box when the change in concentration is unknown. The example given had one negative and one positive value, and professor also addressed that one value would be too large if both were positive. When c...
by Michelle Pham_3H
Tue Nov 14, 2017 10:21 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.43
Replies: 2
Views: 134

Re: 4.43

I think it is asking if you would expect the bond angle to increase from 109.5 (sp^3) to 120 (sp^2) degrees when the ratio of s increases between these hydridized orbitals.
by Michelle Pham_3H
Tue Nov 14, 2017 10:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 109.5 degrees
Replies: 3
Views: 199

109.5 degrees

I am a bit confused about where this value came from. Was it just calculated and given to us, or are we able to determine this value ourselves? Thanks in advance!
by Michelle Pham_3H
Mon Nov 06, 2017 5:42 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity - P, Na, Ar
Replies: 4
Views: 261

Electron Affinity - P, Na, Ar

In Test 3, there was a question that asked us to put several elements in order of decreasing electron affinity. Using the general guideline that electron affinity increases across a period and decreases down a group, I put P, Na, and Ar into the order Ar, P, and Na. The correct answer was P, Na, Ar....
by Michelle Pham_3H
Mon Nov 06, 2017 5:28 pm
Forum: Octet Exceptions
Topic: Noble gas exception
Replies: 4
Views: 382

Noble gas exception

Today in lecture, we discussed the Lewis structure for xenon tetrafluoride and how it can accommodate 12 electrons (4 single bonds, 2 lone pairs). Based on what we have learned, we know that S, P, and Cl can have more than an octet. Why can xenon have more than an octet, and are there any other simi...
by Michelle Pham_3H
Sun Nov 05, 2017 5:32 pm
Forum: Octet Exceptions
Topic: Expanded Octet Max
Replies: 2
Views: 197

Expanded Octet Max

We discussed in lecture how P, S, and CL can all have expanded octets due to their size and vacant d-orbitals. Is there a maximum amount of electrons that their expanded octets can accommodate? And if not, would we just draw our Lewis structures according to formal charge and knowledge that these el...
by Michelle Pham_3H
Sun Nov 05, 2017 5:27 pm
Forum: Lewis Structures
Topic: Lewis Structure Format
Replies: 2
Views: 154

Lewis Structure Format

At the review sessions today, all of the examples done were covalent molecules/compounds. I know that there were several examples in the textbook and in class that were done with brackets. Would those all be considered ionic, and if so would you just use electronegativity trends to determine whether...
by Michelle Pham_3H
Fri Oct 27, 2017 10:52 pm
Forum: Trends in The Periodic Table
Topic: Metals, Nonmetals, and Semimetals/Metalloids
Replies: 2
Views: 189

Metals, Nonmetals, and Semimetals/Metalloids

I think I need to refresh my memory on periodic table trends. I'm familiar with the inert gases and alkali metals, but how can you determine which category (metal, nonmetal, semimetal/metalloid) an element falls into just by looking at the periodic table? Thanks in advance!
by Michelle Pham_3H
Fri Oct 27, 2017 10:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Determining valence electrons for d-block elements [ENDORSED]
Replies: 3
Views: 1449

Determining valence electrons for d-block elements [ENDORSED]

We've started drawing Lewis structures based on our knowledge of electron configurations, and while I'm clear on how many valence electrons s- and p- block elements normally have, is it the same for d-block elements or is that given? Any examples would help too. Thanks in advance!
by Michelle Pham_3H
Sun Oct 22, 2017 8:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Chapter 2 #25 and #29 [ENDORSED]
Replies: 2
Views: 241

Re: Chapter 2 #25 and #29 [ENDORSED]

For Question 2.25, it asks you how many electrons can occupy the given orbitals of an atom: a) 4p-orbitals = 6 electrons (one pair each for px,py,pz) b) 3d-orbitals = 10 electrons (one pair in each of the five orbitals) c) 3s-orbitals = 2 electrons (one pair in one orbital) d) 4f-orbitals = 14 elect...
by Michelle Pham_3H
Sun Oct 22, 2017 8:18 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Different d and f orbitals
Replies: 3
Views: 210

Different d and f orbitals

I know we discussed the different p orbitals (px, py, and pz) in class, but are there different ones for d and f as well? If so, what are the different notations for these orbitals? I didn't get this far in high school chemistry, so I was a bit lost last lecture. Any explanation is greatly appreciat...
by Michelle Pham_3H
Sun Oct 15, 2017 1:26 am
Forum: DeBroglie Equation
Topic: Units for Mass [ENDORSED]
Replies: 3
Views: 196

Units for Mass [ENDORSED]

I noticed that for the questions that pertain to the DeBrogile Equation, kilograms is used to measure mass as part of momentum. For example, in problem 1.39 the mass of the baseball in ounces had to be converted to kilograms. So unless the problem is asking for grams of substance, should I assume th...
by Michelle Pham_3H
Sun Oct 15, 2017 1:19 am
Forum: Properties of Light
Topic: Photons
Replies: 7
Views: 338

Photons

So I'm understanding the general concepts we have been discussing during lecture and the problems we have been practicing, but I'm kind of confused with what exactly a photon is. I know it's a particle that makes up all kinds of light, but if you had to define it in succinct terms without missing an...
by Michelle Pham_3H
Thu Oct 12, 2017 1:03 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Rounding Rule for 5
Replies: 5
Views: 439

Re: Rounding Rule for 5

Thanks everyone!
by Michelle Pham_3H
Fri Oct 06, 2017 8:07 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Rounding Rule for 5
Replies: 5
Views: 439

Rounding Rule for 5

Hi! I'm still trying to wrap my head around why we were told to round to the nearest even number when the number immediately after the last significant figure is 5. In my high school chemistry class this was never discussed, not to say that high school chemistry is that advanced, but this is still a...
by Michelle Pham_3H
Fri Oct 06, 2017 7:41 pm
Forum: Balancing Chemical Reactions
Topic: What’s the quickest way to approaching writing a balanced equation with only one given compound?
Replies: 3
Views: 231

Re: What’s the quickest way to approaching writing a balanced equation with only one given compound?

This only answers your question in regards to combustion. In a combustion reaction, oxygen is always part of the reactants, while water and carbon dioxide are always given off as products. All three are normally in the form of a gas. Combustion reactions are often indicated through burning, metaboli...
by Michelle Pham_3H
Fri Oct 06, 2017 7:33 pm
Forum: SI Units, Unit Conversions
Topic: Do we need to memorize unit conversions? [ENDORSED]
Replies: 9
Views: 1516

Re: Do we need to memorize unit conversions? [ENDORSED]

One way that I remember metric prefixes is kind of antiquated and silly, but I learned it in middle school and I still use it now. It's an acronym called "King Henry Dances Up Down Chocolate Mountain", and it gives you the order of the metric prefixes from largest to smallest (kilo-, hecto...
by Michelle Pham_3H
Fri Oct 06, 2017 7:16 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: G17
Replies: 2
Views: 207

Re: G17

Before rounding off the number to two significant figures (given by 0.20M copper sulfate), I got 12.48446 grams which is very close to your answer.

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