Search found 19 matches

Tue Dec 05, 2017 7:41 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis
Replies: 4
Views: 371

Re: Bronsted vs. Lewis

The bronsted acid donates the H+; while the lewis acid accepts a lone pair.
Tue Dec 05, 2017 7:36 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.29d
Replies: 2
Views: 403

Re: 12.29d

You need to use the formula M1V1=M2V2 to get the new concentration of KOH, which also equals to the concentration of OH- because KOH is a strong base.
Tue Dec 05, 2017 7:32 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Weak Acids and Bases
Replies: 2
Views: 275

Re: Weak Acids and Bases

Strong acid or base can disassociate completely, which means there will only be one arrow toward the right.
Sun Dec 03, 2017 3:30 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Why is Kw value typically used at 25 degrees C [ENDORSED]
Replies: 6
Views: 1083

Re: Why is Kw value typically used at 25 degrees C[ENDORSED]

Because 25 degrees C is the room temperature. If the temperature increase, the Kw will increase as well.
Sun Dec 03, 2017 3:25 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 12.55 Part A
Replies: 2
Views: 344

Re: 12.55 Part A

I think you are talking about the Ka value for Ch3COOH. Those numbers are called acidity constants at 25 c, which are given on page 477 table 12.1.
Mon Nov 27, 2017 8:14 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.14
Replies: 1
Views: 212

11.14

In question 11.14 it asks us to write the reaction quotient for NCl3(g) + 3H2O(l) ---- NH3(g) +3HOCl(aq). Should we calculate the kc or kp for this question?
Mon Nov 27, 2017 8:08 am
Forum: Ideal Gases
Topic: Q and K [ENDORSED]
Replies: 35
Views: 1838

Re: Q and K[ENDORSED]

The formula of Q and K are the same, but they have different meanings.
Fri Nov 17, 2017 6:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs Angular
Replies: 7
Views: 570

Re: Bent vs Angular

They're the same. They occur when lone pairs have more repulsive force than do shared electron pairs.
Fri Nov 17, 2017 6:01 pm
Forum: Hybridization
Topic: Polar/nonpolar [ENDORSED]
Replies: 14
Views: 1865

Re: Polar/nonpolar[ENDORSED]

A polar molecule forms when an atom of high electronegativity bonds with a less electronegative atom. Conversely, the electrons of a non-polar molecule are distributed more equally.
Sun Nov 05, 2017 4:46 pm
Forum: Lewis Structures
Topic: Cl as an Expanded Octet
Replies: 3
Views: 2972

Re: Cl as an Expanded Octet

ClO4^1- is a good example that Cl has expanded valence shell. If you put Cl as the central atom and connect it with O using single bond, you'll see the formal charge of Cl is +3 and O is -1. However, if you consider it as three double bonds and one single bond, the formal charge of Cl will be 0 and ...
Sun Nov 05, 2017 4:35 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Lewis Structures and Formal Charge
Replies: 7
Views: 926

Re: Lewis Structures and Formal Charge

Not always. For those simple Lewis structures such as CH4 and NH3, we know that the formal charge would be 0 and there's only single bond in those molecules. However, for those exceptions to octet rule, such as SO4^2- and ClO4^1-, you need to calculate the formal charge because they have expanded va...
Thu Oct 26, 2017 10:54 pm
Forum: Lewis Structures
Topic: Double or single bonds
Replies: 4
Views: 316

Re: Double or single bonds

When you draw a Lewis dot structure, you can either use two dots or a line between two atoms to represent a chemical bond. If there are two lines or four dots between two atoms, you'll know it's a double bond.
Thu Oct 26, 2017 10:48 pm
Forum: Lewis Structures
Topic: Lewis Dot Structure Example
Replies: 3
Views: 329

Re: Lewis Dot Structure Example

Two (NH4)+ and one (SO4)2- can bond together by ionic bond and form (NH4)2SO4. When you draw the Lewis Dot structure, make sure to put the (NH4)+ on the left and (SO4)2- on the right.
Thu Oct 19, 2017 12:30 pm
Forum: DeBroglie Equation
Topic: Can we use formula E=mv^2 to calculate the total energy?
Replies: 2
Views: 294

Can we use formula E=mv^2 to calculate the total energy?

We know that E=pv and p=mv, which means total energy should equal to mv^2. In the photoelectric experiment, we also know that E=work function+(mv^2)/2. However, work function doesn't equal to (mv^2/2), which means this equation is wrong. Does anyone know where I get wrong? Thank you.
Thu Oct 19, 2017 12:12 pm
Forum: DeBroglie Equation
Topic: λ=c/v VS. λ=h/mv
Replies: 9
Views: 6134

Re: λ=c/v VS. λ=h/mv

In the equation λ=h/mv, v represents the velocity of any particle with momentum; while in the equation λ=c/v, c is a constant number represents the speed of light, which means this equation is only used for photon.
Thu Oct 12, 2017 12:52 pm
Forum: Properties of Light
Topic: Clarification on C=λv
Replies: 10
Views: 1947

Re: Clarification on C=λv

When frequency decreases, wavelength will increase because the speed of light is constant.
Wed Oct 11, 2017 2:29 pm
Forum: Properties of Light
Topic: Calculating the wavelength of light [ENDORSED]
Replies: 5
Views: 514

Re: Calculating the wavelength of light[ENDORSED]

First, you should remember the formula E=hv, where v stands for frequency and h is a constant number. Also, we know that ν = c/λ. If you plug ν = c/λ into the equation E=hv, you'll get E=hc/λ. In some questions they only give you the wavelength instead of the frequency, that's when you can apply thi...
Thu Oct 05, 2017 7:36 am
Forum: Empirical & Molecular Formulas
Topic: F.23 Question [ENDORSED]
Replies: 5
Views: 635

Re: F.23 Question[ENDORSED]

Yes. Also, there's an easy way to do it. Each hydrocarbon in this problem has two carbons, which means the numerators are the same. So you can just compare the denominator by calculating the mass of H2，H2OH and H16.
Thu Oct 05, 2017 7:20 am
Forum: Balancing Chemical Reactions
Topic: Nitrogen
Replies: 5
Views: 463

Re: Nitrogen

Yes. Nitrogen can only maintain in a liquid state at extremely low temperature or extremely high pressure. Its boiling point is 77K under atmospheric pressure, which means in most cases it is gaseous.