Search found 24 matches

by Wu Yuchen A1
Tue Aug 01, 2017 10:43 am
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Why do we analyze the salt equation to find the pH?
Replies: 1
Views: 446

Re: Why do we analyze the salt equation to find the pH?

When titrating strong acid using strong base/strong base using strong acid, when equivalence point is reached, the solution is considered neutral. When titrating weak acid / base however, when the equivalence point is reached, conjugate base/acid in the solution can react with water to form hydroniu...
by Wu Yuchen A1
Mon Jul 31, 2017 10:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 3
Views: 331

Re: Reaction Quotient

The reaction quotient (Q) is similar to the equilibrium constant (K), but K is the constant when the reaction is in equilibrium while Q is for any stage of the reaction except when it is at equilibrium. For extension the value of K can't be influenced by the concentration of reactant or production ...
by Wu Yuchen A1
Mon Jul 31, 2017 10:10 pm
Forum: *Titrations & Titration Calculations
Topic: Stoichiometric Point Ca(OH)2 and HCOOH
Replies: 2
Views: 542

Re: Stoichiometric Point Ca(OH)2 and HCOOH

Before answer we never use Ca(OH)2 as a titration base since it isn't strong base at all.
Your summary is correct. At this situation the mole of hydronium ion = mole of hydroxyl ion (if both the acid and base are strong)
by Wu Yuchen A1
Thu Jul 27, 2017 11:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: The whole range of pH value
Replies: 1
Views: 252

The whole range of pH value

as pKw remains 14 just if temperature is 25 ℃. What will happen to the whole range of pH if temperature is not at 25 ℃? ( Since pH+pOH=pKw, while pKw does not equal to 14, is that possible for pOH to go below zero or the total range of pH just decreases?)
by Wu Yuchen A1
Thu Jul 27, 2017 11:16 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Dilution, HW Problem #12.33
Replies: 1
Views: 211

Re: Dilution, HW Problem #12.33

To solve this question in organized way, you can just follow the secondary questions one by one. To make the question more difficult, you can just try to solve the last question without seeing the first two.
by Wu Yuchen A1
Mon Jul 24, 2017 6:28 pm
Forum: Coordinate Covalent Bonds
Topic: chapter 3 problem 27C help
Replies: 2
Views: 444

Re: chapter 3 problem 27C help

That means the oxidation number of manganese. In the problem that means manganese atom loose 4 electrons when bonding with oxygen atoms.
by Wu Yuchen A1
Mon Jul 24, 2017 6:19 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa+pKb=pKw Conceptually?
Replies: 1
Views: 665

Re: Ka+Kb=Kw Conceptually?

First of all, little correction -- pH + pOH = pKw
I wonder I can explain this as additional hydroxide can react with hydroxonium which is originally in water.
by Wu Yuchen A1
Thu Jul 20, 2017 10:19 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Valence Bond Theory
Replies: 2
Views: 318

Re: Valence Bond Theory

To determine hybridization state of one bonded atom, you can count the electrons density region around the atom(no matter single/double/triple bond, you should consider it as one region). Then you can use the number you count to decide hybridizing state of the atom.
by Wu Yuchen A1
Thu Jul 20, 2017 10:13 am
Forum: Ionic & Covalent Bonds
Topic: 3.61
Replies: 2
Views: 250

Re: 3.61

Through hybridization, elements which are beyond 2 period in p block can utilize d orbitals to place paired valence electrons
by Wu Yuchen A1
Thu Jul 20, 2017 10:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant
Replies: 2
Views: 218

Re: Equilibrium Constant

There is no significant difference between Kc and Kp since both of them are used to describe equilibrium constant. The only difference is that when talking about reactions in gas phases, concentration should be replaced by partial pressure.
by Wu Yuchen A1
Tue Jul 18, 2017 2:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Strength of Repulsion
Replies: 1
Views: 612

Re: Strength of Repulsion

In this question, the only thing you should compare is the strength of repulsion relating to single lone pair/bonded atoms. Since all nucleus are positively charged and have ability to tract electrons, more nucleus means stronger attraction force towards electrons. Since electrons in lone pair are a...
by Wu Yuchen A1
Tue Jul 18, 2017 2:14 pm
Forum: Hybridization
Topic: Bond Order
Replies: 4
Views: 729

Re: Bond Order

IN the case that Lewis structure is completely correct, you can simply count the number of bonds between two atoms and get the result as bond order of the two bonded atoms. Hybridization state depends on the number of regions of electron density. State of hybridization isn't influenced by the bond o...
by Wu Yuchen A1
Sat Jul 15, 2017 3:32 pm
Forum: Ionic & Covalent Bonds
Topic: The use of hidden d orbital
Replies: 2
Views: 235

The use of hidden d orbital

Atoms including sulfur can have more than eight elections on the out most layer when bouds with atoms. This is because sulfur atom can utilize d orbital to form bonds. The question is, should all d orbitals be used up when bonded electrons are more than eight or just depends on specific situation? C...
by Wu Yuchen A1
Sat Jul 15, 2017 3:25 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 3
Views: 341

Re: Resonance

A Lewis Structure that can be drawn differently but still be correct is Resonance? For instance a central atom can have one double bond with any of the three atoms surrounding it. Like in the Course Reader example on page 80. Is the description of resonance very precise in this question? In long ca...
by Wu Yuchen A1
Tue Jul 11, 2017 11:12 pm
Forum: Ionic & Covalent Bonds
Topic: Effective Charge of an Atom
Replies: 2
Views: 370

Re: Effective Charge of an Atom

I guess you are talking about shielding effect? When multiple electrons move around nucleus, different shell experience different effective nucleus charge because inner shell shields out shell.
by Wu Yuchen A1
Tue Jul 11, 2017 11:06 pm
Forum: Ionic & Covalent Bonds
Topic: Polyatomic Lewis Structures
Replies: 5
Views: 663

Re: Polyatomic Lewis Structures

ions form when losing/ gaining several electrons, thus when drawing Lewis structure we should add/subtract electrons.
by Wu Yuchen A1
Fri Jul 07, 2017 11:11 pm
Forum: Balancing Chemical Reactions
Topic: Fundamental H11
Replies: 2
Views: 491

Re: Fundamental H11

To balance equations we learn currently, I recommend you to first find the element exist only once on both sides of equation and you can determine the scale of these two parts of equation. Them with the setted scale, it's easy to balance the remaining stuffs.
by Wu Yuchen A1
Fri Jul 07, 2017 10:54 pm
Forum: Empirical & Molecular Formulas
Topic: Self test 1 #5
Replies: 2
Views: 408

Re: Self test 1 #5

If you divid all mass of elements by relative mass number, you will find the scale of the number of all elements. Simplify the scale and you can get empirical formula.
by Wu Yuchen A1
Fri Jul 07, 2017 10:39 pm
Forum: Formal Charge and Oxidation Numbers
Topic: homework 3.23
Replies: 4
Views: 393

Re: homework 3.23

Element chlorine can have oxidizing state from -1 to +7. The atom can gain one more or lose several elections to reach relatively stable state. Oxidizing state represents the number of electron(s) atom gains/loses to form ion. (Positive means losing while negative means gaining)
by Wu Yuchen A1
Wed Jul 05, 2017 9:55 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: True Or False??
Replies: 2
Views: 344

Re: True Or False??

The answer is false. Electromegnatic waves are a kind of energy. Due to the conservation of energy, it's even impossible for energy of atom to stay the same when emitting electromagnetic waves if no other kind of energy is put in.
by Wu Yuchen A1
Fri Jun 30, 2017 7:40 pm
Forum: Properties of Light
Topic: Lecture 3 blackbody's emit spectrum
Replies: 3
Views: 247

Lecture 3 blackbody's emit spectrum

Today our professor referred that ideal black body can absorb light in any wavelength. Does this mean that the ideal black body can emit all kind of spectrum when in exciting state? In the other word, does ideal black body's emit spectrum equal to the whole spectrum?
by Wu Yuchen A1
Fri Jun 30, 2017 7:23 pm
Forum: Properties of Light
Topic: Chapter 1 Number 19 [ENDORSED]
Replies: 2
Views: 284

Re: Chapter 1 Number 19 [ENDORSED]

Your idea is correct. Without multiplying 1 mold into equation, your answer isn't completed because you can just get 1mol from the question but not 6.02E23 atoms.
by Wu Yuchen A1
Fri Jun 30, 2017 7:16 pm
Forum: Properties of Electrons
Topic: Clarification on "ground state"
Replies: 2
Views: 333

Re: Clarification on "ground state"

In today's lecture our professor was talking about one-electron situation that only one electron move around nucleus (ex. Hydrogen atom or carbon ion losing 5 electrons). In the situation like this, the answer to your question is correct and N=1 means equals to ground state. No idea about what will ...
by Wu Yuchen A1
Fri Jun 30, 2017 12:27 pm
Forum: Properties of Electrons
Topic: Diffraction experiment for electron
Replies: 2
Views: 286

Diffraction experiment for electron

What characters make cristal able to serve as two-line barrier to make electrons diffract?

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