## Search found 33 matches

Mon Feb 11, 2019 1:25 pm
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM 7th ed
Replies: 1
Views: 147

### MIDTERM 7th ed

Will the midterm cover any of the sections beyond 4F (“ENTROPY”) from the 7th ed textbook, such as 4G (“Moleuclar Interpretation of Entropy”) and 4H (“Absolute Entropy”)?
Thu Jan 24, 2019 1:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.11 (b) 7th edition
Replies: 2
Views: 124

### 5J.11 (b) 7th edition

5J.11) Predict shift in equilibria when temperature increases. b) X2 (g) <=> 2X (g) , where X is a halogen. I'm not quite sure how to approach this problem. I don't see the relation between the gas being a halogen and the temperature of the system increasing. Is there a way of telling whether the fo...
Thu Jan 24, 2019 1:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.1 7th Edition
Replies: 1
Views: 77

### 6B.1 7th Edition

6B.1) Original solution has 200.0 mL NaOH solution. Then, 5.00 mL of the original solution is diluted to 500.0 mL which has pH 13.25 a) What is OH- concentration of the original solution? To find the pH of the original solution, I know we have to use the relation c1V1=c2V2. But I'm not sure if I hav...
Thu Jan 24, 2019 1:34 pm
Forum: Polyprotic Acids & Bases
Topic: 6E.3 7th Edition
Replies: 2
Views: 409

### 6E.3 7th Edition

6E.3) Calculate the pH of each of the following solutions of diprotic acids at 25C, ignoring second deprotonations only when the approximation is justified: a) 0.010M H2CO3 (aq); b) 0.10M (C00H)2 (aq); c) 0.20 M H2S (aq) I'm not really sure how to take into consideration the second deprotonation con...
Sun Jan 20, 2019 8:53 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gases
Replies: 7
Views: 326

### Inert Gases

Why does the presence of an inert gas not effect the equilibrium of a mixture?

When an inert gas is added to a system in equilibrium, total pressure increases. Doesn't this mean the system will tend to work towards minimizing the effect of the increased pressure, by Le Chatelier's Principle?
Sun Jan 20, 2019 8:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Kc (Section 5H.3 7th Edition)
Replies: 2
Views: 94

### K and Kc (Section 5H.3 7th Edition)

Do we need to know how to convert between K and Kc using the equation K = (((c°RT)/(P°))^Δn ) x Kc for the test?

This was not covered during lectures but it is part of the reading outlined in the syllabus (section 5H.3 from the 7th edition).
Sun Jan 20, 2019 8:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure
Replies: 2
Views: 112

### Partial Pressure

When writing equilibrium constant expressions, do we use partial pressures only if the reaction in question represents homogeneous equilibrium of gases? If a reaction involves gases and other phase substances, do we still report the activity of the gases in terms of their partial pressures or in ter...
Mon Jan 07, 2019 4:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc Value
Replies: 4
Views: 319

### Re: Kc Value

A large Kc value also means that the free energy of the reactants state is greater than the free energy of the products, which means energy will be released as the forward reaction occurs.
Mon Jan 07, 2019 4:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids
Replies: 4
Views: 149

### Solids and Liquids

Dr. Lavelle mentioned that solids and liquids are not included in K expressions because they are usually in excess.

But what if a solid or liquid in a chemical equation is a limiting reactant, thus not present in excess? Should their concentrations be included in K expressions?
Mon Jan 07, 2019 4:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Activity and Concentration
Replies: 2
Views: 130

### Activity and Concentration

During class, Dr. Lavelle mentioned the relationship between activity and concentration, introducing the relationship a = γ (concentration).

What exactly is activity? And how does activity relate to why we omit units for molar concentration when calculating equilibrium constants?
Thu Nov 29, 2018 2:33 am
Forum: Hybridization
Topic: Difference between hybridization and hybrid orbitals
Replies: 4
Views: 283

### Difference between hybridization and hybrid orbitals

What is the difference between stating the hybridization of an atom and identifying hybrid orbitals of an atom?
Thu Nov 29, 2018 2:19 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.29 (7th edition)
Replies: 2
Views: 134

### 2E.29 (7th edition)

How do you know which of three has the largest dipole moment?
Thu Nov 29, 2018 2:18 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs Nonpolar for CH2Cl2
Replies: 2
Views: 123

### Polar vs Nonpolar for CH2Cl2

Why is CH2Cl2 polar?

Don't the dipole moments for the two C-Cl bonds cancel out?
Sun Nov 25, 2018 4:30 pm
Forum: Bond Lengths & Energies
Topic: Dissociation Energy
Replies: 1
Views: 155

### Dissociation Energy

The textbook describes dissociation energy as the "depth of the well" when potential energy is plotted against internuclear distance. I am referring to the graph given on page 98 (Figure 2D.5) in 7th edition. I don't really understand how this illustrates the definition of dissociation ene...
Sat Nov 10, 2018 7:13 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 1
Views: 375

### Electron Affinity

The textbook defined Electron Affinity as the following: Let X be some element, X(g) + e-(g) = X-(g) Then, Eea(X) = E(X) - E(X-). Thus, electron affinity is described as energy of the neutral element (X) minus energy of anion of element (X-). This makes the trend for Eea increase across a period and...
Sat Nov 10, 2018 7:06 pm
Forum: SI Units, Unit Conversions
Topic: Angstrom and SI Units
Replies: 2
Views: 502

### Angstrom and SI Units

Is Angstrom (10^-10) a SI prefix?
Sat Nov 10, 2018 7:01 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 6
Views: 229

### Re: Bond Lengths

They're determined experimentally.
Thu Nov 01, 2018 12:17 am
Forum: Photoelectric Effect
Topic: Rate at which electrons are emitted
Replies: 2
Views: 265

### Rate at which electrons are emitted

What are some factors that can manipulate the rate at which electrons are emitted? And why exactly doesn't the energy of the incoming photon affect the rate of electron emission from the metal plate?
Thu Nov 01, 2018 12:16 am
Topic: Black Body
Replies: 4
Views: 2194

### Black Body

The textbook defines a 'black body' as an "object that absorbs and emits all frequencies of radiation without favor." However, quantum mechanics is all about energy existing in packets and thus limit to certain frequencies, meaning not "all" frequencies of radiation is possible. ...
Thu Nov 01, 2018 12:10 am
Forum: Trends in The Periodic Table
Topic: Electron Affinity and Eletronegativity
Replies: 1
Views: 205

### Electron Affinity and Eletronegativity

From what I understand about electron affinity and electronegativity, the two seem to be pretty similar conceptually and in terms of periodic trends--they both increase across the period and decrease down a group.

What exactly is the difference between electron affinity and electronegativity?
Fri Oct 26, 2018 3:39 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 7th Edition Example 1B.5 (Page19)
Replies: 2
Views: 139

### Re: 7th Edition Example 1B.5 (Page19)

h with a dash over 2p is already accounted for in the denominator in the equation: uncertainty in x = (1.05457 * 10^-34 J s) / (2 * (1.0 * 10^-3 kg) * (2 * 1.0 * 10^-3 m/s) )

But the textbook multiplies an extra 2 to uncertainty in velocity: (2 x 1.0 x 10^-3 m/s).
Fri Oct 26, 2018 3:37 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin Magnetic Quantum Number
Replies: 6
Views: 594

### Spin Magnetic Quantum Number

I know that the spin magnetic quantum number can take values -1/2 and +1/2, indicating the direction of spin of an electron.

Is it possible for spin magnetic quantum number to equal 0?
Fri Oct 26, 2018 3:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 2
Views: 204

The textbook says the radial distribution function (P) can be used to calculate the probability of finding an electron around the nucleus: P(r) = r^2 R^2 (r). How is this equation derived and what do its components (r) (R) mean? And does this equation to apply to any electron in any shell/subshell/o...
Fri Oct 26, 2018 3:28 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Uncertainity Principle
Replies: 2
Views: 197

### Heisenberg Uncertainity Principle

The Heisenberg Uncertainty Principle is (uncertainity in p) (uncertainity in x) is greater than or equal to (1/2) h bar.

What is exactly is linear momentum p? And why is it important in the context of quantum mechanics and electrons?
Fri Oct 26, 2018 3:27 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 7th Edition Example 1B.5 (Page19)
Replies: 2
Views: 139

### 7th Edition Example 1B.5 (Page19)

For question (a) the question asks to estimate the minimum uncertainty in the position of a marble of mass 1.0g given that its speed is known to within +/- 1.00 mm s-1. In the evaluation of the question, the textbook gives dx = (1.05457 * 10^-34 J s) / (2 * (1.0 * 10^-3 kg) * (2 * 1.0 * 10^-3 m/s) I...
Fri Oct 26, 2018 3:20 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Question 1F: 1
Replies: 1
Views: 100

### Re: Question 1F: 1

Yes, you do not need to know the exact measurements of the atomic radii in order to set those elements in order of decreasing atomic radius. Using the periodic table, the atomic radius increases as you go down a group and decreases as you go across a period from left to right.
Fri Oct 26, 2018 3:16 pm
Forum: Lewis Structures
Topic: Double and Triple Bonds???
Replies: 2
Views: 100

### Re: Double and Triple Bonds???

In double and triple bonds, more than one electron is involved in the covalent bond. For example, in a CO2 molecule, each oxygen atom shares two of its electrons with the carbon atom in order to fill the valence shell—this makes two double bonds between the 2 oxygen atoms and 1 carbon atom. As for a...
Wed Oct 10, 2018 5:42 pm
Forum: Limiting Reactant Calculations
Topic: Question M.5 (Sixth Edition)
Replies: 2
Views: 222

### Re: Question M.5 (Sixth Edition)

(a) To identify the excess reactant use the reaction mole ratio of ClO2 and BrF3, which is 6 mol ClO2 : 2 mol BrF3 (5 mol BrF3) (6 mol ClO2 / 2 mol BrF3) = 15 mol ClO2 , which shows that 5 mol of BrF3 must react with 15 mol ClO2 for BrF3 to go to completion. But since only 12 mol of ClO2 is availabl...
Wed Oct 10, 2018 5:24 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilution Question
Replies: 1
Views: 142

### Re: Dilution Question

You multiply (1 mol Na2CO3) / (2 mol Na+) instead of (2 mol Na+) / (1 mol Na2CO3) because the Na+ and Na2CO3 do not cancel out if you multiply (2.15 * 10^3 mol Na+) / (0.076 mol Na2CO3 / L). [(2.15 * 10^3 mol Na+) / (0.076 mol Na2CO3 / L)] * [(1 mol Na2CO3) / (2 mol Na+)] simplifies to [(2.15 * 10^3...
Wed Oct 10, 2018 5:05 pm
Forum: Significant Figures
Topic: Repeating Decimal
Replies: 3
Views: 849

### Re: Repeating Decimal

To my understanding, yes, you treat repeating decimals numbers, such as 1/3, as numbers with a finite number of decimal places. There are no special rules for significant figures for nonterminating decimals. When performing your calculations do not round nonterminating decimals. So on your calculato...
Wed Oct 03, 2018 4:28 pm
Forum: Molarity, Solutions, Dilutions
Topic: Ions in dilutions
Replies: 2
Views: 73

### Re: Ions in dilutions

When ions dissolve in aqueous solutions, they undergo ionic dissociation, meaning the individual ions are freed from their bonds. For example, when NaCl is dissolved in water, the cation Na+ and anion Cl- completely separate. So, no, it really shouldn’t matter what ion the ion you are solving for is...
Wed Oct 03, 2018 4:15 pm
Forum: Molarity, Solutions, Dilutions
Topic: Fundamentals E.9
Replies: 2
Views: 89

### Re: Fundamentals E.9

First, convert the given mass 5.15 g MgSO4*7H2O into moles using the molar mass of MgSO4*7H2O, which is 246.483 g/mol: (5.15 g MgSO4*7H2O) (mol / 246.483g) = 0.02089 mol MgSO4*7H2O Then, use the molar ratio of MgSO4*7H2O and oxygen, which is (11 mol O / 1 mol MgSO4*7H2O), to find the moles of oxygen...
Wed Oct 03, 2018 1:49 pm
Forum: Empirical & Molecular Formulas
Topic: Confusion on number of moles
Replies: 4
Views: 226

### Re: Confusion on number of moles

For every 1 mole of the molecule, CuCl24H2O, there are 2 moles of the Cl atom involved, giving the molar ratio of 1:2 for CuCl24H2O and Cl, respectively. It’s just like how in every 1 mole of H20, there are 2 moles of H atoms involved.