Search found 73 matches

by William Lan 2l
Thu Mar 15, 2018 3:25 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Figure 9.18 on page 343 [ENDORSED]
Replies: 1
Views: 167

Figure 9.18 on page 343 [ENDORSED]

On pg 343, for figure 9.18 (a), why is it that when heat leaves the system, the entropy of the system increases?
by William Lan 2l
Wed Mar 14, 2018 12:20 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73 b and 8.75 c
Replies: 1
Views: 87

8.73 b and 8.75 c

For 8.73 b, you break 4 mol of c-H bonds from CH4. However, in 8.75 c, you break 1 mol C-H bonds from CH4. Im really confused why this is.
by William Lan 2l
Wed Mar 14, 2018 12:18 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.75
Replies: 2
Views: 170

8.75

For b, how do you know that you break c=c bonds and not something like c-h bonds? Also how do you know that you're forming 1 mol c-c bonds, 1 mol c-o bonds and 1 mol of c-H bonds? Im confused as to determining which bonds are broken/formed
by William Lan 2l
Sat Mar 10, 2018 11:14 am
Forum: *Enzyme Kinetics
Topic: Chapter 15 [ENDORSED]
Replies: 3
Views: 165

Chapter 15 [ENDORSED]

For chapter 15, are we responsible for 15.1-15.15 (omitting 15.9 of course)??
by William Lan 2l
Thu Mar 08, 2018 12:05 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediate [ENDORSED]
Replies: 7
Views: 205

Intermediate [ENDORSED]

How do you determine the intermediate?
by William Lan 2l
Thu Mar 08, 2018 12:04 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow step
Replies: 3
Views: 90

Slow step

How do you determine the slow step?
by William Lan 2l
Thu Mar 08, 2018 12:04 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation [ENDORSED]
Replies: 7
Views: 235

Arrhenius Equation [ENDORSED]

When do you use the Arrhenius Equation?
by William Lan 2l
Fri Mar 02, 2018 7:07 pm
Forum: First Order Reactions
Topic: Integrated Rate Laws [ENDORSED]
Replies: 1
Views: 78

Integrated Rate Laws [ENDORSED]

How do we relate -d[A]/dt with k[A]? Basically, why are they equal to each other? And what's the difference between integrated rate laws and just rate laws in general?
by William Lan 2l
Fri Mar 02, 2018 7:06 pm
Forum: First Order Reactions
Topic: First Order Reactions [ENDORSED]
Replies: 2
Views: 737

First Order Reactions [ENDORSED]

When a reaction is first order, does it mean that it's faster or slower than a second order reaction?
by William Lan 2l
Fri Mar 02, 2018 7:04 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Constant [ENDORSED]
Replies: 3
Views: 127

Rate Constant [ENDORSED]

What exactly is the rate constant? What does K tell us?
by William Lan 2l
Tue Feb 20, 2018 1:13 am
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Ion-selective electrode
Replies: 2
Views: 178

Ion-selective electrode

I'm still confused about the function of the ion-selective electrode? what does it do, exactly?
by William Lan 2l
Tue Feb 20, 2018 1:12 am
Forum: Balancing Redox Reactions
Topic: Finding half reactions
Replies: 4
Views: 191

Finding half reactions

In example 14.8 on pg. 586, how do you find the two reduction half reactions? is it already given to us?
by William Lan 2l
Tue Feb 20, 2018 1:11 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Hydrogen Electrode
Replies: 1
Views: 51

Standard Hydrogen Electrode

I'm still don't quite understand the use of the standard hydrogen electrode? what is it used for exactly?
by William Lan 2l
Tue Feb 13, 2018 9:54 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Ex 9.10 pg. 342
Replies: 1
Views: 80

Ex 9.10 pg. 342

For the problem, it gives us the enthalpy of fusion as 2.292 kJ/mol. Is this a typo? Shouldn't this be the enthalpy of freezing?
by William Lan 2l
Tue Feb 13, 2018 9:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Trouton's rule
Replies: 1
Views: 86

Trouton's rule

Do we need to know Trouton's rule for the midterm? It's in the book on pg. 327
by William Lan 2l
Tue Feb 13, 2018 7:07 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: S=klnW
Replies: 7
Views: 1026

S=klnW

In general, in what instance will we be required to use this equation?? like in what context?
by William Lan 2l
Mon Feb 12, 2018 1:27 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Test #1 Question 1B
Replies: 3
Views: 132

Re: Test #1 Question 1B

Where did you get the CL-CL bonds from? They aren't even in the reaction.
by William Lan 2l
Mon Feb 12, 2018 1:15 am
Forum: Phase Changes & Related Calculations
Topic: Test #1 Question 7
Replies: 1
Views: 94

Test #1 Question 7

What was the correct answer for question 7 on our first test?
by William Lan 2l
Mon Feb 12, 2018 1:07 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Test #1 Question 6
Replies: 2
Views: 103

Test #1 Question 6

How do you approach this problem? We are given 3 C (graphite), yet it tells us that 4 moles of C (graphite) is reacted. So how do we do this problem?
by William Lan 2l
Mon Feb 12, 2018 1:01 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Test #1 Question 1B
Replies: 3
Views: 132

Test #1 Question 1B

Which bond types do we use for bonds broken and which ones do we use for bonds formed for question 1B in our first test?

For bonds broken, I put that we use C=C, C-C, and H-H bonds

For bonds formed, I put that we use C-C and 2 C-H bonds

Is this correct?
by William Lan 2l
Thu Feb 08, 2018 11:57 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: "Molar Convention"
Replies: 2
Views: 73

"Molar Convention"

So when do we use delta G vs. delta G sub r?
by William Lan 2l
Thu Feb 08, 2018 11:56 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Exothermic/Endothermic
Replies: 2
Views: 94

Exothermic/Endothermic

How come for an exothermic reaction, the formation of products is favored by lowering the temperature. Also, why are the products favored by an increase in temperature for an endothermic reaction?
by William Lan 2l
Thu Feb 08, 2018 11:55 am
Forum: Van't Hoff Equation
Topic: van't Hoff Equation
Replies: 2
Views: 271

van't Hoff Equation

How do we know whether we're calculating K1 or k2? Also, when do we even use the van't Hoff Equation in the first place?
by William Lan 2l
Sat Feb 03, 2018 10:17 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta S, H, and G
Replies: 2
Views: 68

Delta S, H, and G

In the solutions manual, I keep on seeing delta S sub r, delta G sub r, and delta H sub r for answers to questions 55 and 57. What does the r stand for? Reactants?
by William Lan 2l
Thu Feb 01, 2018 11:48 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Bulk Matter
Replies: 1
Views: 85

Bulk Matter

What exactly is bulk matter?
by William Lan 2l
Thu Feb 01, 2018 12:55 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible vs Irreversible
Replies: 1
Views: 82

Reversible vs Irreversible

What roles do reversible/irreversible reactions play in relation to change in entropy of a system?
by William Lan 2l
Thu Feb 01, 2018 12:53 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy: Units and Justification
Replies: 1
Views: 90

Re: Entropy: Units and Justification

Entropy is essentially the disorder of a system resulting from the reversible transfer of heat over the absolute temperature of the system (q/T). q is in Joules and T is in K. Thus, q/T is Joules/kelvin.
by William Lan 2l
Thu Feb 01, 2018 12:02 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Question 9.1 part a
Replies: 1
Views: 61

Question 9.1 part a

Can someone explain how to start this problem?
by William Lan 2l
Thu Jan 25, 2018 12:18 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity at constant pressure vs at constant volume [ENDORSED]
Replies: 1
Views: 134

Heat capacity at constant pressure vs at constant volume [ENDORSED]

Why is heat capacity at constant pressure greater than that at constant volume?
by William Lan 2l
Thu Jan 25, 2018 12:04 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Translation/Rotational/Vibrational Energy [ENDORSED]
Replies: 1
Views: 104

Translation/Rotational/Vibrational Energy [ENDORSED]

Do we need to know translational/rotational/vibrational energy for the test? Also, do we need to know their subsequent equations derived from the equipartition theorem?
by William Lan 2l
Wed Jan 24, 2018 11:16 pm
Forum: Calculating Work of Expansion
Topic: Irreversible expansion
Replies: 4
Views: 135

Irreversible expansion

I understand that in an irreversible expansion, the system is not in equilibrium. But what does this conceptually mean? And why is it irreversible?
by William Lan 2l
Wed Jan 24, 2018 10:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Internal Energy
Replies: 5
Views: 187

Internal Energy

If delta P = 0 (constant pressure), why is delta U = q + w? I thought that w = -PdeltaV. If P is 0, there would be no work then right?
by William Lan 2l
Wed Jan 24, 2018 7:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Adding reactions
Replies: 2
Views: 115

Adding reactions

How come when you add N2 + 02 -> 2 NO with 2 NO + O2 -> 2NO2 you get N2 + 2O2 -> 2NO2? Is it because the 2 NO from the first reaction cancels out the 2 NO from the second reaction?
by William Lan 2l
Thu Jan 18, 2018 11:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy [ENDORSED]
Replies: 3
Views: 97

Enthalpy [ENDORSED]

What exactly is enthalpy? I need a conceptual explanation. What does negative/positive enthalpy tell us about a reaction?
by William Lan 2l
Thu Jan 18, 2018 10:06 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Q 8.67
Replies: 1
Views: 95

Q 8.67

How do we approach this problem? Especially for a, what are the steps for estimating the enthalpy of formation of H20? Where do we start?
by William Lan 2l
Thu Jan 18, 2018 9:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Q. 8.65
Replies: 2
Views: 91

Q. 8.65

Can someone explain how to approach this problem without being given an initial reaction? Are we supposed to find the initial reaction ourselves?
by William Lan 2l
Mon Jan 15, 2018 6:22 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q. 8.39
Replies: 2
Views: 144

Q. 8.39

How much heat is need to convert 80.0 g of ice 0.0 degrees C into liquid water at 20.0 degrees C?

Can someone give a conceptual explanation as well as the steps on approaching this problem?
by William Lan 2l
Sat Jan 13, 2018 11:19 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Constant pressure vs. Constant volume
Replies: 1
Views: 128

Constant pressure vs. Constant volume

Why is the heat capacity at constant pressure greater than heat capacity at constant volume?
by William Lan 2l
Sat Jan 13, 2018 11:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Heat Capacity
Replies: 1
Views: 107

Heat Capacity

For heat capacity at constant volume, why do we use delta U? Similarly, for heat capacity at constant pressure, why do we use delta H?
by William Lan 2l
Sat Jan 13, 2018 11:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy and Internal Energy
Replies: 2
Views: 126

Enthalpy and Internal Energy

What's the relationship between Enthalpy and Internal Energy? In other words, how do you relate the two? I just need a conceptual explanation.
by William Lan 2l
Sun Dec 10, 2017 10:54 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: carboxylic strength
Replies: 2
Views: 272

Re: carboxylic strength

For carboxylic acids, the group that is attached to the carboxyl group that is more electronegative causes the carboxylic acid to be more acidic.
by William Lan 2l
Sat Dec 09, 2017 8:55 pm
Forum: Lewis Acids & Bases
Topic: Lewis acids and bases
Replies: 2
Views: 157

Lewis acids and bases

To what extent (for the final) do we have to know Lewis acids and bases other than the fact that Lewis acids accept electrons and Lewis bases donate electrons?
by William Lan 2l
Sat Dec 09, 2017 8:39 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Assuming solution is neutral [ENDORSED]
Replies: 1
Views: 130

Assuming solution is neutral [ENDORSED]

I understand that if [H30] is less than 10^-7, the solution is considered neutral. But if [OH] is greater than 10^-7, does that mean that we also assume the solution is neutral?
by William Lan 2l
Wed Nov 29, 2017 8:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Making the "Assumption" when calculating equilibrium
Replies: 1
Views: 114

Making the "Assumption" when calculating equilibrium

So, I know that you assume x to be negligible when it's less than 5% of initial value. But what is the initial value? Is the initial value the initial concentration of the product/reactant? And how would you know x is less than 5% of initial value if you don't even know what x is?
by William Lan 2l
Tue Nov 28, 2017 11:16 pm
Forum: Naming
Topic: 17.33 (a)
Replies: 2
Views: 137

17.33 (a)

Can someone help me with this problem? How would you tell if HN(CH2CH2NH2)2 is polydentate or not? and if it is, how would you be able to give the maximum number of places the ligand can bind to simultaneously to a single metal center?
by William Lan 2l
Tue Nov 28, 2017 9:38 pm
Forum: Naming
Topic: Polydentate
Replies: 3
Views: 180

Polydentate

How do you tell if something is polydentate vs. monodentate?
by William Lan 2l
Tue Nov 28, 2017 4:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination compounds and complexes
Replies: 2
Views: 125

Coordination compounds and complexes

Can someone briefly explain what coordination compounds and complexes are? Also, what does the coordination sphere tell us?
by William Lan 2l
Mon Nov 20, 2017 9:55 pm
Forum: Naming
Topic: Toolbox 17.1 from Chemistry Textbook
Replies: 2
Views: 91

Toolbox 17.1 from Chemistry Textbook

This toolbox breaks naming coordination compounds into 2 procedures. Procedure A is called "Writing the formula" and procedure B is called "Naming the complex". Do we need to know how to do procedure A and B or just procedure B??
by William Lan 2l
Mon Nov 20, 2017 4:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 2
Views: 116

Bond Angles

Do we have to know the bond angles for every single Lewis structure or just the easy ones like how Linear is 180 degrees?
by William Lan 2l
Mon Nov 20, 2017 3:57 pm
Forum: Properties of Electrons
Topic: Chem Midterm Question Q3C
Replies: 1
Views: 179

Chem Midterm Question Q3C

The computing performance of their supercomputer is only related to the speed of the electron. If more high-energy photons are caught from outer space, would the performance be better?

Why is the answer no?
by William Lan 2l
Sun Nov 19, 2017 5:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Si02 VSEPR
Replies: 2
Views: 211

Si02 VSEPR

What is the VSEPR shape of Si02? Also, is it polar or non-polar and how do you tell?
by William Lan 2l
Sun Nov 19, 2017 5:54 pm
Forum: Hybridization
Topic: Hybridization in General
Replies: 3
Views: 334

Hybridization in General

Can someone explain to me the general concept of Hybridization? I'm still not fully understanding the concept and how to apply it to different orbitals.
by William Lan 2l
Thu Nov 09, 2017 2:45 am
Forum: Trends in The Periodic Table
Topic: s-block vs p-block
Replies: 4
Views: 530

Re: s-block vs p-block

s-block metals have lower ionization energies compared to p-block metals. Thus, due to their low ionization energies, s-block metals tend to form cations since they are more willing to give electrons away. Due to this, they are more reactive.
by William Lan 2l
Tue Nov 07, 2017 3:42 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Post Assessment Module #42
Replies: 1
Views: 153

Post Assessment Module #42

#42: An excited hydrogen atom emits light with a frequency of 1.14 x 10^14 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?

A. n = 5

B. n = 6

C. n = 4

D. n = 7

How do you do this problem (step by step)??
by William Lan 2l
Wed Nov 01, 2017 10:53 pm
Forum: Trends in The Periodic Table
Topic: Problem 2.67 from textbook
Replies: 2
Views: 145

Problem 2.67 from textbook

Which element of each of the following pairs has the higher electron affinity?

Nitrogen or Carbon

Why is the answer Carbon? I thought that as you go down a period, the electron affinity gets higher.
by William Lan 2l
Wed Nov 01, 2017 2:50 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Post- Module #18 and #23
Replies: 1
Views: 167

Re: Post- Module #18 and #23

#18: The delta X is uncertainty in position. It tells us that the uncertainty in position is 1% of .05 nm or .05 x 10^-9 m. So just do 1% of .05 x 10^-9 m and whatever answer you get is your delta X. #23: The delta X in this problem is 10 m since we have to account for everything in between +5 and -5.
by William Lan 2l
Wed Oct 25, 2017 10:38 pm
Forum: Trends in The Periodic Table
Topic: f-orbitals
Replies: 6
Views: 1150

Re: f-orbitals

Keep in mind that the f-orbitals (Lanthanides and Actinides) are on the bottom of the periodic table since there are so many that it can't find on the periodic table. So, starting element 57, look at the bottom of the periodic table (Lanthanides and Actinides -> f-orbitals) and start counting from t...
by William Lan 2l
Wed Oct 25, 2017 8:23 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic ions
Replies: 2
Views: 786

Isoelectronic ions

For the isoelectronic ions Na+, F-, and Mg2+, why is it that Mg2+ has the largest nuclear charge of the 3 (it has the strongest attrition for the electrons and therefore the smallest radius of the 3)?? I thought that as we go down a group, there is shielding which causes electrons to be further from...
by William Lan 2l
Sat Oct 21, 2017 9:01 pm
Forum: Quantum Numbers and The H-Atom
Topic: The 4 Quantum Numbers [ENDORSED]
Replies: 5
Views: 454

The 4 Quantum Numbers [ENDORSED]

Can someone briefly go over the 4 quantum numbers? (n, l, m subscript l, and m subscript s)?

Im stuck specifically with l and m subscript l. What do they mean and what do they show?
by William Lan 2l
Sat Oct 21, 2017 4:07 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: electron configurations [ENDORSED]
Replies: 2
Views: 172

Re: electron configurations [ENDORSED]

you can write 2p^2. Prof Lavelle said that he accepts both ways of writing it. It's just that writing 2px^1 and 2py^1 is more specific and prevents ambiguity to electron spin.
by William Lan 2l
Sat Oct 21, 2017 4:06 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Principle Quantum Number [ENDORSED]
Replies: 3
Views: 189

Principle Quantum Number [ENDORSED]

What exactly is the principle quantum number? I'm not fully understanding the concept.
by William Lan 2l
Fri Oct 13, 2017 9:09 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1.6b
Replies: 2
Views: 170

Re: 1.6b

use the equation (lambda = h/p)......h is Planck's constant (6.626 x 10^-34) and p is momentum (mass x velocity). So with the given mass of the bullet and the velocity, calculate the momentum. Then do Planck's constant/momentum and you will get wavelength.

I hope this helps
by William Lan 2l
Wed Oct 11, 2017 2:16 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Post Module Q. 14
Replies: 3
Views: 247

Post Module Q. 14

14. For large everyday objects does Heisenberg's uncertainty (indeterminacy) principle play any measurable role? A. Yes, the uncertainties in position, speed, and momentum of a stationary object are noticeable or measurable. B. Yes, the uncertainties in position, speed, and momentum of a moving obje...
by William Lan 2l
Tue Oct 10, 2017 5:14 pm
Forum: DeBroglie Equation
Topic: Post-Module Assessment Q. 34
Replies: 4
Views: 239

Post-Module Assessment Q. 34

If an electron (mass 9.11 x 10^-31 kg) has an associated wavelength of 7.28 x 10^-9 m, what is its speed? Is your answer reasonable, why? A. 1.00 x 10-5 m.s-1. Yes. 1.00 x 10-5 m.s-1 is reasonable for e- as it is less than the speed of light, c = 3.0 x 108m.s-1. B.1.00 x 10-5 m.s-1. No. 1.00 x 10-5 ...
by William Lan 2l
Sun Oct 08, 2017 3:39 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
Replies: 12
Views: 571

Re: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30

28. Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. Answer the following three questions. A. What is the kinetic energy of the ejected electron? A. 3.01 x 10^25 J B. 3.98 x 10^-19 J C. 7.96 x 10^-19 J D. ...
by William Lan 2l
Sun Oct 08, 2017 3:29 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Post-Module Assessment Q. 42
Replies: 1
Views: 157

Atomic Spectra Post-Module Assessment Q. 42

42. An excited hydrogen atom emits light with a frequency of 1.14 x 1014 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?

A. n = 5

B. n = 6

C. n = 4

D. n = 7

How do you do this?
by William Lan 2l
Sun Oct 08, 2017 3:15 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Post-Module Assessment Q. 20 [ENDORSED]
Replies: 2
Views: 251

Atomic Spectra Post-Module Assessment Q. 20 [ENDORSED]

20. If 1 million photons in the UV region are absorbed by a hydrogen gas sample how many electrons are excited to a higher energy level?

A) Zero
B) 500,000
C) 1
D) 1 Million

I put my answer as 1 because I thought hydrogen has only 1 electron. So how is the answer incorrect?
by William Lan 2l
Sun Oct 08, 2017 12:28 am
Forum: Photoelectric Effect
Topic: Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30
Replies: 12
Views: 571

Photoelectric Effect: Post Module Assessment Q. 28, 29, and 30

How do you do questions 28, 29, and 30 in the post assessment module for the photoelectric effect?
by William Lan 2l
Sun Oct 08, 2017 12:26 am
Forum: Photoelectric Effect
Topic: Question from online assessment [ENDORSED]
Replies: 1
Views: 119

Re: Question from online assessment [ENDORSED]

The light from the UV range of the electromagnetic spectrum tends to have higher frequencies which means the photons have more energy to overcome the threshold energy of the metal.
by William Lan 2l
Wed Oct 04, 2017 10:02 pm
Forum: Limiting Reactant Calculations
Topic: Page F109 from book (Self-Test M.2A)
Replies: 2
Views: 170

Page F109 from book (Self-Test M.2A)

How do you identify the limiting reactant in the reaction 6 Na + Al2O3 ->2 Al + 3 Na2O when 5.52 g of sodium is heated with 5.1 g of Al2O3?
by William Lan 2l
Mon Oct 02, 2017 7:22 pm
Forum: Balancing Chemical Reactions
Topic: Fundamental H.13
Replies: 4
Views: 264

Re: Fundamental H.13

Cool thanks, and how do you balance Fe2O3 + CO -> Fe3O4 + CO2 from the first part of H.11?
by William Lan 2l
Mon Oct 02, 2017 7:05 pm
Forum: Balancing Chemical Reactions
Topic: Fundamental H.13
Replies: 4
Views: 264

Fundamental H.13

In this question, we are asked to balance NO+O2 -> NO2 in the second part of the problem.

I know this seems easy, but I can't wrap my head around balancing it. How do you do it (step by step)?

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