Search found 105 matches

Tue Mar 10, 2020 10:25 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Memorization?
Replies: 4
Views: 67

Re: Memorization?

There are other forms of these equations that may be helpful to memorize because they don't appear on the formula sheet.

One example is ln(k1/k2) = Ea/R[(1/T2)-(1/T1)]
Tue Mar 10, 2020 10:22 pm
Forum: General Rate Laws
Topic: Equations
Replies: 5
Views: 59

Re: Equations

We do not need to know how to, since the integrated rate laws will be provided on the formula sheet. However, according to my TA, it may be useful to memorize other helpful forms of these laws that do not appear on the formula sheet.
Tue Mar 10, 2020 10:19 pm
Forum: General Rate Laws
Topic: pseudo rate laws
Replies: 5
Views: 53

Re: pseudo rate laws

It is a way of note that you are finding/using a different k value. I've also seen different k values expressed in other terms such as k2, where the original k value is expressed as k1.
Tue Mar 10, 2020 10:17 pm
Forum: General Rate Laws
Topic: 7A.3
Replies: 6
Views: 70

Re: 7A.3

Rates are generally never expressed as negative, even when referring to reactants.
Tue Mar 10, 2020 10:15 pm
Forum: General Rate Laws
Topic: 7A.15
Replies: 6
Views: 63

Re: 7A.15

How do we decide which experiments to use to determine the rates with respect to A and B? thank you! First, you have to realize that C is zero order reactant. Now that C is independent and doesn't affect the other concentrations, to find the order of A, compare experiments 2 and 4 because the conce...
Mon Mar 02, 2020 9:55 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: 6O.1
Replies: 2
Views: 90

Re: 6O.1

A 1.0 m NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction (c) With no overpotential at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis? The solution manual uses the E^o ...
Mon Mar 02, 2020 9:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Metal in Cell Diagram
Replies: 1
Views: 21

Re: Metal in Cell Diagram

We add inert electrodes such Pt(s), C(s), etc. when there is no other metal present in the cathode or anode, or when both the oxidizing and reducing species are in the same solution.
Mon Mar 02, 2020 9:48 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 6.45
Replies: 1
Views: 25

Re: 6.45

Yes a strongly reducing metal is the same as a strong reducing agent, and a strongly oxidizing metal is the same as a strong oxidizing agent.
Mon Mar 02, 2020 9:46 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.3c
Replies: 4
Views: 81

Re: 6N.3c

You can convert torr to atm by dividing the torr values by 760. The units will then cancel out as you solve the equation.
Mon Mar 02, 2020 9:40 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: 6O.1
Replies: 2
Views: 90

6O.1

A 1.0 m NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction (c) With no overpotential at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis? The solution manual uses the E^o v...
Tue Feb 25, 2020 12:06 am
Forum: Balancing Redox Reactions
Topic: Explain the charges in this reaction
Replies: 1
Views: 21

Re: Explain the charges in this reaction

The total charge of Hg2+ is 4+. Since there are two electrons depicted in the reactants, the total charge of the reactants is 2+. This balances with the products, which has a total charge of 2+ as well since the charge on Hg2 as a whole is 2+.
Mon Feb 24, 2020 11:54 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in the change in free gibbs energy equation
Replies: 4
Views: 63

Re: n in the change in free gibbs energy equation

It's the number of electrons that are reduced/oxidized in the reaction.
Mon Feb 24, 2020 11:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M5
Replies: 1
Views: 38

Re: 6M5

An inert electrode only needs to be added when there is no metal present. The cathode and anode are independent of this, meaning that the cathode can have an inert electrode while the anode doesn't, or vice versa. In this case, the anode has a metal present, which is Hg(l), since mercury is a metal ...
Mon Feb 24, 2020 11:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 c
Replies: 1
Views: 24

Re: 6L.5 c

An inert electrode must be added when there is no metal in the cathode or anode. In this case, H2(g), H+(aq), Cl-(aq), Cl2(g), aren't metals, so an inert electrode such as Platinum must be added to both sides. I believe Dr. Lavelle mentioned that the order within the cathode and anode don't matter, ...
Mon Feb 24, 2020 11:38 pm
Forum: Balancing Redox Reactions
Replies: 7
Views: 73

The charge on both sides of the reaction need to be balanced, so add electrons to whichever side has a higher charge.
Sat Feb 22, 2020 1:07 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: HW 6N #1 b)
Replies: 1
Views: 27

Re: HW 6N #1 b)

I saw elsewhere that this is just an error in the solution manual. The number of moles of electrons should be 1.
Sat Feb 22, 2020 12:59 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.7b
Replies: 2
Views: 58

6N.7b

Calculate Ecell for each of the following concentration cells: (b) Pt(s)|H2(g, 1 bar)|H1(aq, pH 5 4.0)||H1(aq, pH 5 3.0)|H2(g, 1 bar)|Pt(s) When I wrote the half reactions, I got (2H+) + (2e-) -> H2 and H2 -> (2H+) + (2e-) I would assume that n=2 based on the half reactions, but the answer key says ...
Fri Feb 21, 2020 6:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum [ENDORSED]
Replies: 4
Views: 62

Platinum[ENDORSED]

In cell diagrams, is it possible for platinum to only be on one side?
Fri Feb 21, 2020 5:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7
Replies: 1
Views: 38

6L.7

Write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions: (a) AgBr(s) -> Ag+(aq) + Br-(aq), a solubility equilibrium In the half reaction for the anode, the answer key gives the following reaction: AgBr(s) + e- -> Ag(s) + Br-(aq) Why doesn't...
Fri Feb 21, 2020 5:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5
Replies: 4
Views: 72

6L.5

Write the half-reactions, the balanced equation for the cell reaction, and the cell diagram for each of the following skeletal equations:
(d) Au+(aq) -> Au(s) + Au3+(aq)

How do you know what the cathode and anode is?
Mon Feb 10, 2020 9:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Polyprotic Acids
Replies: 3
Views: 30

Re: Polyprotic Acids

Just found a section in the textbook that says that the only polyprotic acid that we would need to calculate the concentrations for the second deprotonation is sulfuric acid. Why do we need to do the same for H3PO4?
Mon Feb 10, 2020 9:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X is to small
Replies: 8
Views: 145

Re: X is to small

What values do you use to calculate if the percent at the end is less than 5.
Mon Feb 10, 2020 9:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.1
Replies: 1
Views: 36

Re: 5J.1

The equilibrium constant K always remains constant, so any change in the values of the reactants has to be accounted for by another change. A) H2 decreases to account for the increase in CO2. This is because the value of the products (numerator) has to remain constant. B) CO2 will decrease to accoun...
Mon Feb 10, 2020 9:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Polyprotic Acids
Replies: 3
Views: 30

Polyprotic Acids

How do you know if you can ignore the second ionization when calculating the pH of polyprotic acids?
Mon Feb 03, 2020 6:27 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Value of R [ENDORSED]
Replies: 1
Views: 249

Value of R[ENDORSED]

Why does the value of R has to be altered depending on if the problem gives constant volume or constant pressure?
Mon Feb 03, 2020 6:26 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.15
Replies: 2
Views: 28

4F.15

(a) Using Trouton’s rule, estimate the boiling point of dimethyl ether, CH3OCH3, given that H(vap) = 21.51 kJ/mol. (b) Using standard reference sources available in your library or on the Internet, find the actual boiling point of dimethyl ether and compare this value with the value obtained by usin...
Mon Feb 03, 2020 6:15 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy and Entropy
Replies: 2
Views: 30

Re: Degeneracy and Entropy

The greater the degeneracy, the more disorder a system has, therefore resulting in a great value of entropy.
Mon Feb 03, 2020 6:13 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Microstates
Replies: 5
Views: 32

Re: Microstates

Adding on to the comment above, an increased value of microstates results in more disorder is a system, therefore increasing the value of entropy.
Mon Feb 03, 2020 6:12 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Changes Due to Temperature
Replies: 2
Views: 26

Re: Entropy Changes Due to Temperature

Although exothermic and endothermic are two different reactions, in terms of calculating entropy, you don't have to worry about whether the reaction is exothermic or endothermic. The change in temperature will always be calculated as T(final) - T(initial).
Mon Jan 27, 2020 9:53 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sig Figs for Celsius
Replies: 1
Views: 19

Sig Figs for Celsius

4A.19 A piece of copper of mass 20.0 g at 100.0 8C is placed in a vessel of negligible heat capacity but containing 50.7 g of water at 22.0 8C. Calculate the final temperature of the water. Assume that no energy is lost to the surroundings. Are there any special rules for sig figs for calculations r...
Sun Jan 26, 2020 11:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Week 4 Homework
Replies: 11
Views: 116

Re: Week 4 Homework

This past week we also went over 4E.3
Sun Jan 26, 2020 11:04 pm
Forum: Phase Changes & Related Calculations
Topic: Solids, liquids, and gases
Replies: 4
Views: 36

Solids, liquids, and gases

Why do solids and gases have a lower heat capacity than water?
Sun Jan 26, 2020 11:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpies of formation
Replies: 7
Views: 143

Re: Standard enthalpies of formation

I google the enthalpies of formation because not all of them are given in the textbook. I'm sure if a test like this ever appear on an exam Prof. Lavelle would provide us with a table of enthalpies of formation.
Sun Jan 26, 2020 10:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Reaction Enthalpies
Replies: 2
Views: 26

Re: Standard Reaction Enthalpies

Prof. Lavelle provided us with 3 different methods. Using bond enthalpies was the second method he gave us. If the bond enthalpies aren't provided, the third method can be used, which is subtracting standard enthalpies of formation for the reactants from the standard enthalpies of formation for the ...
Sun Jan 26, 2020 10:53 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy of Vaporization and Fusion
Replies: 5
Views: 36

Enthalpy of Vaporization and Fusion

Why is the enthalpy of vaporization greater than the enthalpy of fusion.
Mon Jan 20, 2020 9:24 pm
Forum: Calculating the pH of Salt Solutions
Topic: NH4F
Replies: 1
Views: 70

NH4F

Will NH4F produce and acidic or basic solution?
Mon Jan 20, 2020 9:23 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Self Check 6D.4A
Replies: 1
Views: 90

Re: Self Check 6D.4A

In order to determine whether the solutions of the salts will be acidic, neutral, or basic, you must consider the cation and the anion of the salt. First check if the anion to see if it's acidic, neutral, or basic (Table 6D.2 gives a list of acidic, neutral, and basic anions). If the anion is acidic...
Mon Jan 20, 2020 9:06 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6.19
Replies: 1
Views: 80

6.19

Hemoglobin (Hb) molecules in blood carry O2 molecules from the lungs, where the concentration of oxygen is high, to the tissues where it is low (see the Interlude following Focus 5). In the tissues the equilibrium H3O+(aq) + HbO2- (aq) : HHb(aq) + H2O(l) + O2(aq) releases oxygen. When muscles work h...
Mon Jan 20, 2020 9:01 pm
Forum: Polyprotic Acids & Bases
Topic: Deprotonation
Replies: 3
Views: 81

Deprotonation

Why do we typically disregard the second deprotonation of polyprotic acids?
Tue Jan 14, 2020 11:18 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Expansion
Replies: 5
Views: 36

Expansion

Does expanding the volume affect the equilibrium?
Mon Jan 13, 2020 5:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ATP Hydrolysis
Replies: 2
Views: 18

ATP Hydrolysis

Could someone explain ATP hydrolysis and its connection to the class?
Mon Jan 13, 2020 5:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: The Value of Kw
Replies: 3
Views: 24

Re: The Value of Kw

The value of Kw changes when heat is added to the system. Since the autoprotolysis of water is an endothermic reaction, adding heat will increase the value of Kw because the reaction will favor the formation of products more. In other words, the equilibrium will shift to the right.
Mon Jan 13, 2020 5:11 pm
Forum: Ideal Gases
Topic: Dividing by volume
Replies: 3
Views: 33

Re: Dividing by volume

It doesn't matter how you solve for pressure, however the most simple way is to just divide nRT by volume assuming that the problem gives you values for n, r, and t.
Mon Jan 13, 2020 5:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Thermodynamic Stability
Replies: 6
Views: 64

Thermodynamic Stability

How do we determine if K, Cl2, of F2, is thermodynamically more stable in problem 5I.13?
Mon Jan 13, 2020 5:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 5.39
Replies: 1
Views: 24

Re: Homework 5.39

I couldn't find a Table 5E.2 either so I would assume that it's a typo. Question 5.39 appears to be referring to Table 5G.2 anyways so I would just use that.
Wed Jan 08, 2020 5:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure of gas
Replies: 5
Views: 55

Re: Partial Pressure of gas

Psi is another unit of pressure.
Wed Jan 08, 2020 5:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook question 5I.3
Replies: 2
Views: 38

Re: Textbook question 5I.3

The K value for this reaction is 160. Since HI (2.21x10^-3 M) is the product and H2 (unknown) and I2 (1.46x10^-3 M) are the reactants, the expression will look like this:

160 = (2.21x10^-3)^2 / (H2)(1.46x10^-3)

Solving for H2 gives you 2.1x10^-5 M.
Wed Jan 08, 2020 5:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 2 #19
Replies: 2
Views: 46

Re: Chemical Equilibrium Part 2 #19

You forgot that solids are not factored into the expression, so As should be removed.
Wed Jan 08, 2020 5:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure
Replies: 3
Views: 52

Re: Partial Pressure

The partial pressures will be different. In this case, the partial pressure in the second container will be higher. Keeping in mind that K = products/reactants, since K must remain a constant, the partial pressure of the product O2 must be higher to match the higher partial pressure of the reactant ...
Wed Jan 08, 2020 4:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 1
Views: 63

5I.13

(a) In an experiment, 2.0 mmol Cl2(g) was sealed into a reaction vessel of volume 2.0 L and heated to 1000. K to study its dissociation into Cl atoms. Use the information in Table 5G.2 to calculate the equilibrium composition of the mixture. (b) If 2.0 mmol F2 was placed into the reaction vessel ins...
Tue Dec 03, 2019 11:45 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 6
Views: 78

Re: Coordination Number

You can attempt to visualize the molecule, but your safest bet is drawing the lewis structure every time. For example, you can infer that CH4 has a coordination number of 4 since the 4 hydrogens are attached to the central atom Carbon.
Tue Dec 03, 2019 11:43 am
Forum: Naming
Topic: Iron vs Ferrate
Replies: 5
Views: 43

Re: Iron vs Ferrate

Ferrate is used when iron appears in an anionic complex. This is because when iron appears in an anionic complex, we take its latin name ferrum and replace -um with -ate.
Tue Dec 03, 2019 11:29 am
Forum: Bronsted Acids & Bases
Topic: Stronger Acids and Bases
Replies: 2
Views: 40

Re: Stronger Acids and Bases

You can also look at bond lengths and the resulting anion stability between molecules to determine which acids are stronger.
Tue Dec 03, 2019 11:26 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sig Figs for ph/pOH calculations
Replies: 1
Views: 39

Sig Figs for ph/pOH calculations

Just wanted to bring up that the sig fig rules for ph/pOH calculations are different than the rules for normal sig figs. If you are given 3 sig figs in a question, your final answer doesn't necessarily have 3 sig figs, but rather has 3 decimal places. Here is an example: 0.012 M of H3O+ = -log(0.012...
Tue Dec 03, 2019 11:16 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.9
Replies: 5
Views: 56

Re: 6B.9

You are using the correct formula to find the concentration of OH, which is [M]=10^-POH. Plugging in the numbers you get: 10^-14.176 = 6.668 x 10^-15 M, which is the correct answer.
Sat Nov 30, 2019 12:15 am
Forum: Bronsted Acids & Bases
Topic: Naming Acids
Replies: 2
Views: 39

Re: Naming Acids

What are the rules for naming acids?
Sat Nov 30, 2019 12:07 am
Forum: Lewis Acids & Bases
Topic: Homework 6A 17
Replies: 2
Views: 44

Re: Homework 6A 17

Another way to look at it is that acidic oxides are oxides that reacts with water to form a solution of a Bronsted acid. SO3 is an example of an acidic oxide because when it reacts with water, it forms H2SO4. SO3 + H20 --> H2SO4. Since H2SO4 is an acid, SO3 is an acidic oxide.
Sat Nov 30, 2019 12:05 am
Forum: Bronsted Acids & Bases
Topic: 6A.17b
Replies: 5
Views: 64

Re: 6A.17b

SO3 is basic, not acidic. Acidic oxides are oxides that reacts with water to form a solution of a Bronsted acid. SO3 is an example of an acidic oxide because when it reacts with water, it forms H2SO4. SO3 + H20 --> H2SO4. Since H2SO4 is an acid, SO3 is an acidic oxide. It is also useful to not that ...
Fri Nov 29, 2019 3:31 pm
Forum: Bronsted Acids & Bases
Topic: Naming Acids
Replies: 2
Views: 39

Naming Acids

Are we expected to know how to name acids? For example, in question 6A.7, the problem asks us to name the acid:

6A.7 Below are molecular models of two oxoacids. Write the name of each acid and then draw the model of its conjugate base. (I don't have the molecules shown)
Tue Nov 26, 2019 3:10 pm
Forum: Bronsted Acids & Bases
Topic: J.17
Replies: 2
Views: 39

J.17

In each of the following salts, either the cation or the anion is a weak acid or a weak base in water. Write the chemical equation for the proton transfer reaction of this cation or anion with water: (a) NaC 6 H 5 O; (b) KClO; (c) C 5 H 5 NHCl; (d) NH 4 Br. How do you determine whether the cation or...
Mon Nov 25, 2019 8:27 pm
Forum: Naming
Topic: ferrate
Replies: 4
Views: 47

Re: ferrate

Ferrum refers to the latin name for iron and then the compound has an overall negative charge so you add ate to make it ferrate Cooper is right in this context. Although ferrate is known as the polyatomic ion [FeO4]2-, in this context, ferrate refers to the metal in the coordination compound molecu...
Mon Nov 25, 2019 8:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Naming
Replies: 2
Views: 30

Re: Naming

Lavelle has a chart of all the names on his website. You can find it by clicking on "Naming Coordination Compounds" link. You should definitely memorize all of the names on his chart.
Mon Nov 25, 2019 8:20 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: determining if polydentate
Replies: 3
Views: 60

Re: determining if polydentate

Correct me if I'm wrong but I believe HN(CH2CH2NH2)2 is tridentate because the central atom would be nitrogen, which is attached to a hydrogen and 2 CH2CH2NH2 molecules.
Mon Nov 25, 2019 8:14 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: polydentate
Replies: 2
Views: 49

Re: polydentate

All of the compounds that you listed can be polydentates:

HN(CH2CH2NH2)2 is tridentate, CO3^2- is mono or bidentate, and oxalate is bidentate.
Mon Nov 25, 2019 8:10 pm
Forum: Naming
Topic: Naming Ligands
Replies: 1
Views: 37

Re: Naming Ligands

You don't need to know them, but I believe Lavelle gives us full credit if we use those names. On Lavelle's website, you can find a list of ligand names that Lavelle accepts.
Fri Nov 15, 2019 5:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 5
Views: 74

Re: Bond Angles

We are expected to know the shape of the molecule but not the exact bond angles. However, when there are lone pairs surrounding the central atom, we are expected to know that the bond angles are slightly less compared to central atoms with no lone pairs.
Fri Nov 15, 2019 5:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.21 c
Replies: 2
Views: 48

2E.21 c

For SO2Cl2, the solutions say that there are two possible dot structures. One of them has a double bond and 2 lone pairs attached to the oxygen, while the other has a single bond and 3 lone pairs attached to the oxygen. I understand how the reasoning behind both dot structures, but does Dr. Lavelle ...
Fri Nov 15, 2019 5:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.19 C and D
Replies: 1
Views: 20

Re: 2E.19 C and D

The molecules in both c and d both have a bent shape because the central atom formula is AX2E, or in other words the central atom is connected to two bonds and has one lone pair. When this bent shape occurs, the bond angles are slightly less than 120 degrees because there are 3 concentrations of ele...
Fri Nov 15, 2019 5:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.21 a & d
Replies: 2
Views: 30

2E.21 a & d

Could someone explain the shape and bond angles of C2H4? I don't understand why it's trigonal planar.

Also, I don't understand the answer for the shape and bond angles of N2H4. If someone could explain that as well that would be great!
Fri Nov 15, 2019 5:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.19 b
Replies: 1
Views: 20

2E.19 b

Could someone explain the shape and bond angles of (CH3)2Be? I don't understand why the shape is tetrahedral about carbon atoms.
Sat Nov 09, 2019 11:18 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Differences between the intermolecular forces
Replies: 2
Views: 99

Re: Differences between the intermolecular forces

They all describe the same types of intermolecular forces.
Sat Nov 09, 2019 11:06 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Vapor Pressure
Replies: 2
Views: 52

Re: Vapor Pressure

Vapor pressure is correctly defined in the post above. Knowing what vapor pressure is can help you solve problems like 3F.19 part (b) Explain why the vapor pressure of diethyl ether (C2H5OC2H5) is greater than that of water. Since water has hydrogen bonds and C2H5OC2H5 does not, the molecules are he...
Sat Nov 09, 2019 11:02 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Ion-Ion interactions
Replies: 5
Views: 39

Re: Ion-Ion interactions

Also keep in mind that ion-ion interactions are much stronger than other interactions between ions and molecules.
Sat Nov 09, 2019 12:36 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Boiling Points
Replies: 6
Views: 144

Boiling Points

Explain the difference in the boiling points of AsF3 (63 degrees C) and AsF5 (-53 degrees C).

I'm trying to understand this problem. Why does AsF3 have a higher boiling point? I thought that more electrons means a higher boiling point.
Sat Nov 09, 2019 12:20 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F.1
Replies: 1
Views: 36

3F.1

Identify the types of attractive intermolecular interactions that might arise between molecules of each of the following sub- stances: (a) NH2OH; (b) CBr4; (c) H2SeO4; (d) SO2. I understand a, b, and d but why does H2SeO4 have dipole-dipole interactions? I don't understand why it is a polar molecule.
Sat Nov 02, 2019 3:02 pm
Forum: Dipole Moments
Topic: London Dispersion vs Van der waals
Replies: 2
Views: 44

London Dispersion vs Van der waals

What's the difference between london dispersion and van der waals forces?
Sat Nov 02, 2019 3:00 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizable vs Polarizing
Replies: 6
Views: 86

Re: Polarizable vs Polarizing

Another way to put it is that polarizing power increases among cations from left to right and bottom to top, while polarizability increases from right to left and top to bottom.
Sat Nov 02, 2019 2:54 pm
Forum: Ionic & Covalent Bonds
Topic: Strength of covalent bonds (2d.3)
Replies: 3
Views: 56

Re: Strength of covalent bonds (2d.3)

Recall that ionic bonds form between molecules with a high difference in electronegativity, usually those with a electronegativity difference greater than 2. BaBr2 is the only molecule that primarily forms ionic bonds because the difference in electronegativity between Ba and Br is greater than 2. O...
Sat Nov 02, 2019 2:38 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power
Replies: 3
Views: 54

Re: Polarizing Power

Polarizing power increases from left to right, from bottom to top on a periodic table.
Sat Nov 02, 2019 2:23 pm
Forum: Octet Exceptions
Topic: Expanded Valence Shells
Replies: 4
Views: 55

Expanded Valence Shells

Up to how many electrons can be held in the valence shell of capable elements?
Wed Oct 23, 2019 11:35 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Order of electron configuration
Replies: 6
Views: 72

Re: Order of electron configuration

The 3d orbital has a slightly lower energy level than the 4s orbital, which is why 3d comes before 4s. The 3d orbital is filled up with electrons first, then the 4s orbital, then the 4p orbital.
Wed Oct 23, 2019 11:33 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 13
Views: 483

Re: Electron Configurations

What does he mean when he writes x, y, and z during electron configuration? Is that necessary? x, y, and z represent the different orbital orientations. Some orbitals may be lined up along x axis, others along the y axis, and others along the z axis. The reason why you write x, y, or z is to specif...
Wed Oct 23, 2019 11:24 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.15
Replies: 3
Views: 52

Re: 1D.15

The principle quantum number (n) is the number before the letter in the given orbital. To find the angular momentum quantum number (l) you use to following: s; l=0 p; l=1 d; l=2 f; l=3 For part a, n=6 since the orbital is 6p, and l=1, since it is a p orbital. For part b, n=3 since the orbital is 3d,...
Wed Oct 23, 2019 11:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: order
Replies: 3
Views: 50

Re: order

D-orbitals have a slightly lower energy level than s-orbitals in the same period, therefore d-orbitals are filled with electrons first before s-orbitals. For example, the 3d orbital would be filled with electrons before the 4s orbital.
Wed Oct 23, 2019 5:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.5
Replies: 4
Views: 41

Re: 2A.5

If you remember in class, Cu is an exception for telling the electron configuration from the periodic table. From reading the periodic table, we would expect the configuration to be [Ar]3d^9 4s^2, BUT through experiments, scientists have found that the e- configuration is actually [Ar]3d^10 4s^1 be...
Wed Oct 23, 2019 4:52 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.5
Replies: 4
Views: 41

2A.5

Give the ground-state electron configuration expected for each of the following ions: (a) Cu 1+ ; (b) Bi 3+ ; (c) Ga 3+ ; (d) Tl 3+ For part A, I thought that the answer was [Ar]3d^84s^2 but the solution manual says that the answer is [Ar]3d^10. Why are the electrons from the 4s orbital put into the...
Thu Oct 17, 2019 6:44 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer and Lyman series
Replies: 5
Views: 57

Re: Balmer and Lyman series

Also the Balmer series deals with visible light while the Lyman series deals with ultraviolet light.
Thu Oct 17, 2019 6:40 pm
Forum: DeBroglie Equation
Topic: De Broglie Problem
Replies: 4
Views: 46

Re: De Broglie Problem

After converting the values, plugging in each value would look like this:

(6.626x10^-34 kg ms^2 s^-1)/(1.675x10^-27kg x 100x10^-12m) = 3.96x10^3m/s
Thu Oct 17, 2019 6:33 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1B.25 HW
Replies: 1
Views: 32

Re: 1B.25 HW

All you have to do is draw a square with the length equal to the diameter of the actual atom. The area would represent the potential space the electron could be.
Thu Oct 17, 2019 6:30 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty Value
Replies: 8
Views: 90

Re: Uncertainty Value

The uncertainty value would be 0.2pm because the position could be at 2.34 to 2.36.
Mon Oct 14, 2019 2:12 pm
Forum: DeBroglie Equation
Topic: 1B.15
Replies: 2
Views: 58

Re: 1B.15

Yes, the original velocity of the ejected electron is used to solve this question. The first step is to find the energy of the photon, which can be calculated by adding the kinetic energy of the ejected electron to the energy required to remove the electron from the metal surface. Recall that kineti...
Wed Oct 09, 2019 5:46 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Finding Wavelength of Light
Replies: 3
Views: 81

Re: Finding Wavelength of Light

Adding on the the post above, wavelength is equal to the speed of light divided by frequency.
Wed Oct 09, 2019 5:40 pm
Forum: Properties of Electrons
Topic: Balmer/Lyman series
Replies: 5
Views: 52

Re: Balmer/Lyman series

I would definitely be familiar with those series and I wouldn't be surprised if we need to know them for future tests.
Wed Oct 09, 2019 5:33 pm
Forum: Properties of Light
Topic: Speed of Light constant
Replies: 7
Views: 52

Re: Speed of Light constant

I've been using 3.00x10^8 m/s for module and homework problems and have been just fine.
Wed Oct 09, 2019 5:26 pm
Forum: Properties of Light
Topic: Homework Problems
Replies: 3
Views: 69

Re: Homework Problems

You can find the list of homework problems in the syllabus. I would just go through each section and see which ones apply to what Lavelle has lectured on so far.
Wed Oct 09, 2019 5:24 pm
Forum: Properties of Light
Topic: Self-test 1A.1B
Replies: 4
Views: 48

Re: Self-test 1A.1B

I believe since we use the equation c = w*f, then 3e8= 98.6e6x. to solve for x (wavelength) then divide by the frequency. I got 3.05 meters. Are c and w*f constant values in the equation you used? C is a constant value which is the speed of light. Lavelle introduced it in lectures as 3.00x10^8 m/s ...
Sun Oct 06, 2019 12:12 am
Forum: Empirical & Molecular Formulas
Topic: Hydrates
Replies: 2
Views: 61

Re: Hydrates

I would assume not, but this may be something good to double check with Lavelle or a TA. I do remember this question from the homework though.
Sun Oct 06, 2019 12:09 am
Forum: Balancing Chemical Reactions
Topic: Diatomic elements?
Replies: 8
Views: 124

Re: Diatomic elements?

In response to Lauren, I believe that chemical equations will already show that oxygen by itself is diatomic, as well as the other diatomic molecules. Also, an easy way to remember the diatomic molecules is: Have (hydrogen) No (nitrogen) Fear (fluorine) Of (oxygen) Ice (iodine) Cold (chlorine) Beer ...
Sun Oct 06, 2019 12:02 am
Forum: Limiting Reactant Calculations
Topic: Steps to Finding the Limiting Reactant
Replies: 3
Views: 79

Re: Steps to Finding the Limiting Reactant

You only need to use the molar mass of one reactant to find the product, so you can keep the molar masses of the products separated. First, convert the grams given of a particular reactant to moles. Then, use the molar ratio of the balanced equation to determine how much of a particular product is c...
Sat Oct 05, 2019 3:57 pm
Forum: Limiting Reactant Calculations
Topic: Order of atoms in molecules
Replies: 6
Views: 97

Order of atoms in molecules

Is there a specific order atoms have to be in? For example, in glucose, how do we know that carbon comes first, then hydrogen, then oxygen.