Search found 51 matches

by Tatiana Hage 2E
Mon Mar 12, 2018 9:34 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Homogeneous Catalysts
Replies: 3
Views: 121

Re: Homogeneous Catalysts

Enzymes tend to be homogeneous catalysts because they're usually in the same phase as the molecule it reacts with, to speed up the decomposition of a molecule.
by Tatiana Hage 2E
Mon Mar 12, 2018 9:33 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Distinguishing a Catalyst
Replies: 4
Views: 128

Re: Distinguishing a Catalyst

A reactant is consumed by the reaction, and a catalyst is not.
by Tatiana Hage 2E
Mon Mar 12, 2018 9:32 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Adsorption
Replies: 3
Views: 110

Re: Adsorption

Absorption is the process in which a fluid is dissolved by a liquid or a solid. Adsorption is the process in which atoms, ions or molecules from a substance (gas, liquid or dissolved solid) adhere to a surface of the adsorbent. Adsorption can be used to separate out unwanted substances.
by Tatiana Hage 2E
Mon Mar 05, 2018 7:53 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams- Line Notation with Pt
Replies: 1
Views: 115

Re: Cell Diagrams- Line Notation with Pt

Platinum is an inert conductor that is added to the half reaction that has no conducting solids. You place a line if the elements are in different phases, and a comma if they are in the same phase.
by Tatiana Hage 2E
Tue Feb 27, 2018 9:35 pm
Forum: General Rate Laws
Topic: Elementary Reactions
Replies: 4
Views: 117

Re: Elementary Reactions

An elementary reaction is a chemical reaction in which one or more chemical species react directly to form products in a single reaction step and with a single transition state.
by Tatiana Hage 2E
Tue Feb 27, 2018 9:19 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Unique Average Rate vs. Average Rate
Replies: 3
Views: 102

Re: Unique Average Rate vs. Average Rate

A unique rate is a rate of appearance/disappearance of any of the species in a reaction divided by its stoichiometric coefficient; when average rate is calculated, the coefficient is not taken into account.
by Tatiana Hage 2E
Tue Feb 27, 2018 9:17 pm
Forum: General Rate Laws
Topic: Negative 1/a
Replies: 8
Views: 238

Re: Negative 1/a

There is a negative sign because the concentration of the reactant decreases during the reaction.
by Tatiana Hage 2E
Fri Feb 23, 2018 7:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Electrode
Replies: 4
Views: 117

Re: Inert Electrode

Also, inert electrodes like platinum do not participate in the redox reaction and are present so that current can flow through the cell.
by Tatiana Hage 2E
Fri Feb 23, 2018 7:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Spontaneous Directions [ENDORSED]
Replies: 7
Views: 178

Re: Spontaneous Directions [ENDORSED]

If the standard potential is positive, ∆G is negative and the reaction has a spontaneous tendency to form products.
If the standard potential is negative, ∆G is positive and the reverse of the cell reaction is spontaneous, so the cell reaction has a spontaneous tendency to form reactants.
by Tatiana Hage 2E
Fri Feb 23, 2018 7:27 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Initial rates
Replies: 5
Views: 159

Re: Initial rates

We use the initial rate because it is the fastest rate and the only time that we know the concentrations of the reactants, since the rate decreases as the reactants are used up.
by Tatiana Hage 2E
Wed Feb 14, 2018 2:47 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.47 Isothermal Irreversible Free Expansion
Replies: 3
Views: 153

Re: 9.47 Isothermal Irreversible Free Expansion

It would be the same as ΔSsys of part a, the isothermal and reversible process. ΔSsurr = 0 for free expansion so ΔStot = ΔSsys.
by Tatiana Hage 2E
Wed Feb 14, 2018 2:42 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isothermal system
Replies: 5
Views: 317

Re: Isothermal system

Work = 0 in free expansion because there is no external pressure applied, so P=0 and therefore w=0. Since ΔU = 0, that means that q=0 as well, so no heat is transferred into the surroundings.
by Tatiana Hage 2E
Wed Feb 14, 2018 2:27 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Isothermal/Isobaric/Irreversible/Reversible/Other Topics Covered
Replies: 3
Views: 175

Re: Isothermal/Isobaric/Irreversible/Reversible/Other Topics Covered

At equilibrium, ΔSsys = - ΔSsurr.
Also, ΔG = 0 for a reaction at equilibrium.
by Tatiana Hage 2E
Wed Feb 07, 2018 10:14 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy and work
Replies: 3
Views: 96

Re: Gibbs free energy and work

Gibbs free energy is defined as the maximum useful work (excluding work associated with volume changes of the system) that a system can do on the surroundings when the process occurs reversibly at constant temperature and pressure.
by Tatiana Hage 2E
Wed Feb 07, 2018 10:06 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Calculating Degeneracy
Replies: 3
Views: 154

Re: Calculating Degeneracy

W = the number of microstatesnumber of particles in the system
by Tatiana Hage 2E
Mon Feb 05, 2018 11:49 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: max work [ENDORSED]
Replies: 1
Views: 79

Re: max work [ENDORSED]

G is defined as the maximum non-expansion work under constant temperature and pressure. Since work done by the system is negative, deltaG < w, so deltaG is the maximum work that may be done.
by Tatiana Hage 2E
Tue Jan 30, 2018 1:58 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Test question [ENDORSED]
Replies: 16
Views: 488

Re: Test question [ENDORSED]

The textbook says the first law of thermodynamics is that the internal energy of an isolated system is constant, so I think that would be sufficient.
by Tatiana Hage 2E
Tue Jan 30, 2018 1:50 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 8
Views: 389

Re: Heat Capacity

Liquids have a higher heat capacity than gases or solids so their slope is going to be less steep.
by Tatiana Hage 2E
Tue Jan 30, 2018 1:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: isothermal
Replies: 3
Views: 116

Re: isothermal

The temperature stays constant in an isothermal process. For an ideal gas, in an isothermal process, ΔU = 0 = Q − W, so Q = W.
by Tatiana Hage 2E
Tue Jan 23, 2018 11:51 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard enthalpy of formation
Replies: 3
Views: 91

Re: standard enthalpy of formation

The standard enthalpy change of formation of a compound is the enthalpy change which occurs when one mole of the compound is formed from its elements under standard conditions, and with everything in its standard state. However, the standard enthalpy change of a reaction is the enthalpy change which...
by Tatiana Hage 2E
Tue Jan 23, 2018 11:39 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: system of vacuum
Replies: 4
Views: 144

Re: system of vacuum

Yes because no matter or energy can be exchanged with the surroundings.
by Tatiana Hage 2E
Tue Jan 23, 2018 11:38 am
Forum: Administrative Questions and Class Announcements
Topic: Formula Sheet
Replies: 2
Views: 105

Re: Formula Sheet

There's a link on the class website called Constants and Equations where you can find the formulas.
by Tatiana Hage 2E
Tue Jan 16, 2018 12:07 pm
Forum: Phase Changes & Related Calculations
Topic: Types of Systems
Replies: 10
Views: 302

Re: Types of Systems

If the matter cannot be transferred through the boundary but energy can be exchanged with the surroundings, then that is a closed system. For an isolated system, neither energy nor matter can be exchanged with the surroundings.
by Tatiana Hage 2E
Tue Jan 16, 2018 12:02 pm
Forum: Phase Changes & Related Calculations
Topic: What does it mean when a gas expands reversibly and isothermally?
Replies: 1
Views: 82

Re: What does it mean when a gas expands reversibly and isothermally?

A reversible isothermal expansion is an increase in volume at constant temperature. A reversible reaction does more work because all heat is converted to work.
by Tatiana Hage 2E
Tue Jan 16, 2018 11:58 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 3
Views: 122

Re: Hess's Law

Hess's Law states that the overall reaction enthalpy is the sum of the reaction enthalpies of the steps into which the reaction can be divided. To use Hess's Law to find the enthalpy of a given reaction, we find a sequence of reactions with known reaction enthalpies that adds up to the reaction of i...
by Tatiana Hage 2E
Wed Jan 10, 2018 3:33 pm
Forum: Phase Changes & Related Calculations
Topic: State Properties: q vs. qp
Replies: 3
Views: 116

Re: State Properties: q vs. qp

Heat is dependent on the path or the way the state of the system changes.
by Tatiana Hage 2E
Wed Jan 10, 2018 3:28 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy is a state property
Replies: 13
Views: 404

Re: Enthalpy is a state property

Enthalpy is a state function because it depends only on the state of the system and not on the path taken to reach its value.
by Tatiana Hage 2E
Wed Jan 10, 2018 3:16 pm
Forum: Phase Changes & Related Calculations
Topic: Energy and Phase Changes
Replies: 5
Views: 208

Re: Energy and Phase Changes

Melting only requires enough energy for the molecules to escape from their sites in the solid, but for vaporization, you need enough energy to be able to break most of the intermolecular attractions.
by Tatiana Hage 2E
Mon Dec 04, 2017 7:59 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acid and Base vs Lewis Acid and Base
Replies: 3
Views: 173

Re: Bronsted Acid and Base vs Lewis Acid and Base

Bronsted definition: an acid is a proton (H+ ion) donor, and a base is a proton acceptor.
Lewis definition: an acid is an electron acceptor, and a base is an electron donor.
by Tatiana Hage 2E
Mon Dec 04, 2017 7:04 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Zinc Nitrate
Replies: 2
Views: 132

Re: Zinc Nitrate

Hope this picture helps!
by Tatiana Hage 2E
Sun Nov 26, 2017 6:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw molecular shape
Replies: 4
Views: 399

Re: Seesaw molecular shape

The seesaw shape occurs when a molecule has a central atom bonded to 4 other atoms and 1 lone pair.
by Tatiana Hage 2E
Sun Nov 26, 2017 6:11 pm
Forum: Naming
Topic: Using Roman Numerals
Replies: 2
Views: 106

Re: Using Roman Numerals

The roman numerals indicate the oxidation state of the metal in the complex.
by Tatiana Hage 2E
Sat Nov 18, 2017 10:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW Problem 4.15c
Replies: 2
Views: 107

Re: HW Problem 4.15c

Oxygen is less electronegative, so it is more likely to share its valence electrons than Fluorine, which is very electronegative.
by Tatiana Hage 2E
Sat Nov 18, 2017 10:06 pm
Forum: Bond Lengths & Energies
Topic: Bond Order
Replies: 2
Views: 193

Re: Bond Order

Bond orders can give you an indication of the stability of a bond. A high bond order indicates more attraction between electrons, so the atoms are held together more tightly. With a lower bond order, there is less attraction between electrons so the atoms are held together more loosely. The higher t...
by Tatiana Hage 2E
Sat Nov 11, 2017 8:59 pm
Forum: Lewis Structures
Topic: 3.67 a.
Replies: 2
Views: 135

Re: 3.67 a.

I think you are correct, because that Lewis structure gives both atoms a formal charge of 0.
by Tatiana Hage 2E
Fri Nov 10, 2017 11:20 am
Forum: Lewis Acids & Bases
Topic: Lone Pairs in Bases?
Replies: 2
Views: 187

Re: Lone Pairs in Bases?

Yes, an atom with a lone-pair of electrons can be a Lewis base because it donates its electron pair to a Lewis acid.
by Tatiana Hage 2E
Fri Nov 10, 2017 11:11 am
Forum: Lewis Structures
Topic: Radicals in structures [ENDORSED]
Replies: 3
Views: 192

Re: Radicals in structures [ENDORSED]

It also helps to check the formal charges of each atom. For example, with HOCO, placing the unpaired electron on the carbon gives it a formal charge of 0.
by Tatiana Hage 2E
Fri Nov 10, 2017 11:07 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polar vs nonpolar vs ionic
Replies: 11
Views: 854

Re: Polar vs nonpolar vs ionic

The formation of an ionic bond is the result of the transfer of one or more electrons from a metal onto a non-metal. Polar bonding is the unequal sharing of electrons between two different non-metal atoms. Nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegat...
by Tatiana Hage 2E
Sun Oct 29, 2017 11:52 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground state and electron configuration
Replies: 2
Views: 130

Re: Ground state and electron configuration

The electron configuration for electrons at the ground state will be at the lowest energy state possible for that atom.
by Tatiana Hage 2E
Sun Oct 29, 2017 11:45 am
Forum: Trends in The Periodic Table
Topic: Two Special Elements in Periodic Table
Replies: 3
Views: 184

Re: Two Special Elements in Periodic Table

Cu is the other unique element. A completely full or half full d sub-level is more stable than a partially filled d sub-level, so an electron from the 4s orbital is excited and rises to a 3d orbital. Their electron configurations are - Cr: [Ar] 3d54s1 and Cu: [Ar]3d104s1
by Tatiana Hage 2E
Tue Oct 24, 2017 11:35 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 3d and 4s
Replies: 5
Views: 241

Re: 3d and 4s

For chromium and copper, a completely full or half full d sub-level is more stable than a partially filled d sub-level, so an electron from the 4s orbital is excited and rises to a 3d orbital.
by Tatiana Hage 2E
Tue Oct 24, 2017 11:29 am
Forum: Photoelectric Effect
Topic: Rydberg
Replies: 11
Views: 508

Re: Rydberg

n(initial)-n(final) gives me a negative frequency. Is this right? You should get a negative number because you are going from a higher energy state to a lower energy state. Quantitatively, you would be subtracting a not as negative number from a negative number. The negative result from this indica...
by Tatiana Hage 2E
Tue Oct 24, 2017 11:16 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: principal quantum numbers
Replies: 2
Views: 138

Re: principal quantum numbers

This link might help explain it: http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch6/quantum.html "Because they have opposite electrical charges, electrons are attracted to the nucleus of the atom. Energy must therefore be absorbed to excite an electron from an orbital in which the electro...
by Tatiana Hage 2E
Thu Oct 19, 2017 11:37 am
Forum: Photoelectric Effect
Topic: Rydberg
Replies: 11
Views: 508

Re: Rydberg

n(initial)-n(final) gives me a negative frequency. Is this right?
by Tatiana Hage 2E
Thu Oct 19, 2017 11:33 am
Forum: Properties of Electrons
Topic: 1.57
Replies: 3
Views: 231

Re: 1.57

For tests, should we know that 486 nm represents blue light, 700 nm is red, and so on?
by Tatiana Hage 2E
Thu Oct 12, 2017 11:29 am
Forum: Photoelectric Effect
Topic: Problem 1.7 HW
Replies: 4
Views: 252

Re: Problem 1.7 HW

I solved the problem and got 150 pm as well, which is the answer given in the solutions manual.
by Tatiana Hage 2E
Wed Oct 11, 2017 10:38 am
Forum: Properties of Light
Topic: Chapter 1 Question 9
Replies: 4
Views: 231

Re: Chapter 1 Question 9

Hz is 1 cycle per second, so it is always interchangeable with s^-1
by Tatiana Hage 2E
Fri Oct 06, 2017 1:19 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactants - Neither?
Replies: 2
Views: 159

Re: Limiting Reactants - Neither?

You would know when there are no limiting reactants in an equation if both reactants produced the same mass of a product.
by Tatiana Hage 2E
Fri Oct 06, 2017 12:51 pm
Forum: SI Units, Unit Conversions
Topic: Sig Figs [ENDORSED]
Replies: 16
Views: 1738

Re: Sig Figs [ENDORSED]

There are 2 sig figs in 0.053 since the 0's before 53 do not count.

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