## Search found 8 matches

Sun Jan 29, 2017 7:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Clarification on Quiz 1 Prep - Question 2
Replies: 2
Views: 333

### Re: Clarification on Quiz 1 Prep - Question 2

Make sure to understand that an isolated system means that it can't exchange anything with outside boundaries. Which is why the change in U is 0, since nothing every changed with the system.
Wed Jan 11, 2017 8:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Chapter 8.55, Hess's Law
Replies: 4
Views: 514

### Chapter 8.55, Hess's Law

I am having trouble understanding why the O2 in the 2Al+O2-- Al2O3 equation, is multiplied by 3/2. I know we are trying to cancel it out to get the equation needed, but nothing in that equation was multiplied, just the O2. Could someone explain?
Sun Jul 24, 2016 11:38 pm
Forum: Hybridization
Topic: FALL 2011 MIDTERM Q.6
Replies: 2
Views: 418

### Re: FALL 2011 MIDTERM Q.6

When writing the composition and hybridization you write it in that form...σ(C2sp^2,O2sp^2). First you look at what type of bond is being formed, whether a sigma or pi bond. Then you look at which two elements are involved and their hybridization. I am using the C-O bond at the top right. It has two...
Sun Jul 17, 2016 6:29 pm
Forum: *Molecular Orbital Theory Applied To Transition Metals
Topic: MO with positive or negative charge
Replies: 1
Views: 714

### MO with positive or negative charge

If there is a compound like CN^-, do we add an extra electron to the C or the N? Also, if it were CN^+, where would we take an electron from?
Sun Jul 10, 2016 5:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape from AXE model
Replies: 2
Views: 555

### Re: Shape from AXE model

AX2 is bent, an example would be SO2. Both O have a double bond with S and the S has a lone pair, making it bent.
Sun Jul 10, 2016 5:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape v.s Name of Shape
Replies: 3
Views: 430

### Re: Molecular Shape v.s Name of Shape

If it helps, I call the name of the shape of the molecule which just uses the bonding pairs the electron geometry. As for the structure that uses both the lone and bonding pairs, I call that the molecular shape.
Sun Jul 03, 2016 11:41 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in Position + velocity [ENDORSED]
Replies: 1
Views: 325

### Re: Uncertainty in Position + velocity[ENDORSED]

First, the mass of that "something" would have to be in kg, so you would have to convert the grams to kg. There are 1000g in 1kg, so you would divide 6.23 x 10^4 g by 1000, giving you 62.3 kg. Then 3.08% indicates that the uncertainty in velocity is 3.08% of actual value, 3.499 x 10^-2 m/s...
Sun Jun 26, 2016 12:52 pm
Forum: Significant Figures
Topic: Significant figures [ENDORSED]
Replies: 9
Views: 1382

### Significant figures[ENDORSED]

Can someone please further explain how many significant figures to use when writing an answer. I am still a bit confused.