Search found 63 matches

by Lily Benitez 2G
Sat Mar 16, 2019 10:57 pm
Forum: General Rate Laws
Topic: unique rate
Replies: 3
Views: 102

Re: unique rate

The unique rate is the rate of formation and disappearance of molecules in a reaction and it is divided by the coefficients. The unique rate will be the same for product and reactant.
by Lily Benitez 2G
Sat Mar 16, 2019 8:57 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 3
Views: 94

Re: Nernst Equation

It relates the reduction potential of an electrochemical reaction to the standard electrode potential, temperature, and concentrations of the chemical species going through reduction and oxidation.
by Lily Benitez 2G
Sat Mar 16, 2019 8:38 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 3
Views: 46

Re: Activation Energy

Activation energy and the rate are closely related. When we have a high activation energy the reaction will tend to be slower. Because fewer molecules will have enough energy to make it over the barrier.
by Lily Benitez 2G
Sat Mar 16, 2019 8:34 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exergonic
Replies: 2
Views: 29

Re: Exergonic

Yes, when Gibbs free energy is negative the reaction is exergonic because energy was lost.
by Lily Benitez 2G
Sat Mar 16, 2019 8:30 pm
Forum: Calculating Work of Expansion
Topic: Work
Replies: 1
Views: 88

Re: Work

I depends on what kind of information is given. Sometimes you have to manipulate the equations to obtain something that will accommodate the values given.
by Lily Benitez 2G
Sat Mar 16, 2019 8:27 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: half lives
Replies: 1
Views: 81

Re: half lives

The rate law let's us calculate the rate of a reaction from concentrations that are given to us from reactants. Then when derived it shows the reactants as a function of time. When we have a high k value it means that the reaction is proceeding quickly.
by Lily Benitez 2G
Sat Mar 16, 2019 8:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 5
Views: 60

Re: Platinum

When there is no metal present to conduct the flow of electrons from anode to cathode that is when we use an inert electrode like platinum.
by Lily Benitez 2G
Sat Mar 16, 2019 8:18 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Frequency factor units
Replies: 2
Views: 86

Re: Frequency factor units

A would have the same units of k. So depending on what order the reaction is the units vary.
by Lily Benitez 2G
Sat Mar 16, 2019 8:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Slow and Fast step
Replies: 4
Views: 145

Re: Slow and Fast step

From all the problems I have done the slow and fast steps were labelled. If we are asked to identify it, we would have to be given k of the overall reaction to see what step matches it and that would be our slow step.
by Lily Benitez 2G
Sat Mar 16, 2019 8:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: concentration cell vs galvanic cell
Replies: 3
Views: 53

Re: concentration cell vs galvanic cell

A concentration cell is made of two half-cells with the same electrodes, but differing in concentrations. The purpose for this is to dilute the solution that is more concentrated. This heavily relies on the concentration in order for the reaction to keep going. That is why the higher concentration i...
by Lily Benitez 2G
Sat Mar 16, 2019 8:03 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Buffer solutions
Replies: 1
Views: 93

Re: Buffer solutions

Buffer solutions resist change to pH and this is because of the presence of an equilibrium between the acid and its conjugate base. Very little is used up in neutralizing the reaction which then pH increase.
by Lily Benitez 2G
Sat Mar 16, 2019 7:59 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Collision model
Replies: 3
Views: 46

Re: Collision model

The collision model a occurs only when the reactants collide enough energy and in the proper orientation. It explains why certain chemical reaction happen more quickly at higher temps. The activated complex theory relates the rate of reaction to an equilibrium between the reactants and a transition ...
by Lily Benitez 2G
Sat Mar 16, 2019 7:54 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Transition State
Replies: 3
Views: 38

Re: Transition State

The transition sates are the peaks of your profile. Let's say you have two steps and you have an intermediate. The first peak would be your reactants going to your intermediate that is your fist transition state. Your second would be your intermediates going to your products.
by Lily Benitez 2G
Sat Mar 16, 2019 7:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conjugate Base and Acid
Replies: 4
Views: 68

Re: Conjugate Base and Acid

A conjugate acid is a base with a hydrogen ion added to it. And a conjugate base is what is left over after an acid has donated a proton during a chemical reaction.
by Lily Benitez 2G
Sat Mar 16, 2019 7:48 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions in Basic Solutions
Replies: 1
Views: 78

Half Reactions in Basic Solutions

When balancing half reactions in basic solutions do we need to add water to both sides and the add OH-? I just get confused because for acidic solutions you just add water and then H+.
by Lily Benitez 2G
Fri Mar 15, 2019 9:10 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm
Replies: 4
Views: 111

Re: Midterm

Thank You! Just saw it
by Lily Benitez 2G
Fri Mar 15, 2019 7:43 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm
Replies: 4
Views: 111

Midterm

Nanotechnologists have found ways to create and manipulate structures containing only a few molecules. However, orienting the molecules in specific ways to assemble such structures can be difficult. Calculate the entropy of a solid nano structure made of 64 molecules in which the molecules (i) are a...
by Lily Benitez 2G
Fri Mar 15, 2019 1:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test #1
Replies: 3
Views: 111

Re: Test #1

Thank you!
by Lily Benitez 2G
Fri Mar 15, 2019 1:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure
Replies: 4
Views: 113

Partial Pressure

At 68. Celsius Kp=9.15×10^-3 for reaction
I2(s)--->I2(g).
What is the equilibrium partial pressure of I2(g) at 68 Celsius.
Do we use I2(s) when calculating?
I thought Kp was equal to PI2(g).
by Lily Benitez 2G
Fri Mar 15, 2019 12:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test #1
Replies: 3
Views: 111

Test #1

Does anyone have the final concentrations for question 3 part c in test 1? I don't know if I did my calculations right.
by Lily Benitez 2G
Thu Mar 14, 2019 1:37 am
Forum: General Rate Laws
Topic: Rate Law
Replies: 1
Views: 22

Rate Law

Substance A decomposes in a first-order reaction and its half life is 355 s. How much time must elapse for the concentration of A to decrease to (a) one-eighth of its initial concentration; (b) one-fourth of its initial concentration; (c) 15% of its initial concentration; (d) one-ninth of its initia...
by Lily Benitez 2G
Wed Mar 13, 2019 7:41 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst Problems
Replies: 1
Views: 25

Re: Catalyst Problems

I'm sure we will and it will probably look like the example we had in class today, where there were multiple steps and we had to figure out what was acting as a catalyst and what was an intermediate.
by Lily Benitez 2G
Wed Mar 13, 2019 7:38 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts vs Intermediates
Replies: 4
Views: 54

Re: Catalysts vs Intermediates

So what I got form today is that catalyst are already present in the reaction, and in a later step they are removed. The intermediates are produced later and not originally present in the reaction. Only to be used up by the reaction in another step.
by Lily Benitez 2G
Wed Mar 13, 2019 7:24 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity of Water
Replies: 3
Views: 105

Re: Heat Capacity of Water

A unit change in kelvin is the same change in Celsius. The equation states per kelvin/Celsius so if one unit of kelvin changes so does 1 unit of Celsius.
by Lily Benitez 2G
Wed Mar 13, 2019 7:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode and Cathode
Replies: 8
Views: 114

Re: Anode and Cathode

The anode is the oxidation and the cathode is the reduction in the reaction.
by Lily Benitez 2G
Tue Mar 12, 2019 5:22 pm
Forum: Van't Hoff Equation
Topic: Test #2
Replies: 5
Views: 177

Re: Test #2

the ionic dissociation of water is given by the following reaction: the deltaH for the reaction is 58 kJ/mol. The Kw for the reaction at 25 degree Celsius is 10 ^-14. Is the pH of 7 acidic or basic at 10 degree Celsius? 2H20 --> H3O+ + OH- You have to start by using the Van't Hoff equation which is ...
by Lily Benitez 2G
Tue Mar 12, 2019 12:24 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: instantaneous and unique rate
Replies: 6
Views: 146

Re: instantaneous and unique rate

The average rate of reaction is an average rate which is calculated by taking the change in concentration over a time period. This is just an approximation of the reaction rate in the interval. It does not mean that the reaction has this rate throughout the time interval or even at any instant durin...
by Lily Benitez 2G
Tue Mar 12, 2019 12:17 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: rxn mechanisms
Replies: 3
Views: 42

Re: rxn mechanisms

If we know what the slowest step of the mechanism is, this let's us find the rate equation. This tells us how if we can increase the rate by increasing the concentration of certain reactants.
by Lily Benitez 2G
Tue Mar 12, 2019 12:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acid/Base Concentration vs. Weak Acid/Base Concentration
Replies: 2
Views: 44

Re: Strong Acid/Base Concentration vs. Weak Acid/Base Concentration

Any acid that dissociates 100% into ions is a strong acid. If it does not dissociate 100%, it is a weak acid. Same goes for strong and weak bases.
by Lily Benitez 2G
Tue Mar 12, 2019 3:06 am
Forum: Calculating Work of Expansion
Topic: Reversible Expansion
Replies: 1
Views: 77

Re: Reversible Expansion

Reversible reactions that occur in closed systems will somehow reach equilibrium. During this time the concentration of both P and R do not change. But that does not mean that the reaction has stopped. The forward and reverse reactions are continuing but at equal rates.
by Lily Benitez 2G
Tue Mar 12, 2019 3:02 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step
Replies: 6
Views: 73

Re: Slow Step

I don't think this information will be given to us. During class we learned that the slow step if what determines the overall rate for the reaction, so we should be able to pinpoint that step.
by Lily Benitez 2G
Tue Mar 12, 2019 3:00 am
Forum: General Rate Laws
Topic: Derivations
Replies: 3
Views: 45

Re: Derivations

You should be able to manipulate the formulas given on the formula sheet to accommodate the given information.
by Lily Benitez 2G
Sun Dec 09, 2018 10:47 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: acids and bases in 14b
Replies: 1
Views: 113

Re: acids and bases in 14b

Yes, he spoke of doing calculation to find KA and KB of acids and bases.
by Lily Benitez 2G
Sun Dec 09, 2018 10:45 pm
Forum: Amphoteric Compounds
Topic: Amphiprotic vs Amphoteric
Replies: 2
Views: 119

Re: Amphiprotic vs Amphoteric

These terms describe properties of both acids and bases. Amphiprotic refers to a substance that can either gain or lose a proton, and amphoteric refers to a substance that can act as either an acid or a base.
by Lily Benitez 2G
Sun Dec 09, 2018 10:42 pm
Forum: Conjugate Acids & Bases
Topic: Definition of conjugate base
Replies: 2
Views: 120

Re: Definition of conjugate base

A Conjugate base is a substance formed when an acid loses a hydrogen ion. Considered a base because it can gain a hydrogen ion to reform the acid.
by Lily Benitez 2G
Sun Dec 02, 2018 9:41 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs Lewis
Replies: 4
Views: 103

Re: Bronsted vs Lewis

Bases and acids can be considered to fit in the Lewis and bronsted definition but not all fall in to this category. For example, "the HF molecule as a whole cannot be considered an electron acceptor as there is no room for more electrons,so HF first dissociates and then the H accepts the electr...
by Lily Benitez 2G
Sun Dec 02, 2018 9:37 pm
Forum: Naming
Topic: 7th edition 9C.1
Replies: 1
Views: 35

Re: 7th edition 9C.1

For metals we sometimes use the Latin name when they are in complex so for iron it is ferrate.
by Lily Benitez 2G
Sun Dec 02, 2018 9:33 pm
Forum: Naming
Topic: Polyatomic ions
Replies: 1
Views: 50

Re: Polyatomic ions

Yes I believe it would be important when finding an overall charge of a complex molecule .
by Lily Benitez 2G
Sun Dec 02, 2018 9:31 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 7th edition 9C.7
Replies: 1
Views: 40

Re: 7th edition 9C.7

The correct answer is the second one and that is because the NH2 groups are close together. Which means they can form the ring formation with another complex. The other combination don't have the groups close enough to form the ring.
by Lily Benitez 2G
Sun Nov 25, 2018 7:58 pm
Forum: Octet Exceptions
Topic: Understanding Expanded Octets
Replies: 1
Views: 125

Re: Understanding Expanded Octets

Since n=3 the d sub shell has 5 orbitals. Although the energy of empty 3d-orbitals is ordinarily higher than that of the 4s orbital, that difference is small and the additional d orbitals can fit more electrons. d orbitals participate in bonding with other atoms and an expanded octet is produced. 
by Lily Benitez 2G
Sun Nov 25, 2018 7:53 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Dipole
Replies: 3
Views: 56

Re: Dipole

A polar molecule has to have a permanent dipole moment and the charges shouldn't fluctuate like they would in an induced dipole.
by Lily Benitez 2G
Sun Nov 25, 2018 7:51 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Dipole-Dipole forces
Replies: 3
Views: 62

Re: Dipole-Dipole forces

We have to see the difference in the charges. If the difference is big enough the molecule will have an overall dipole moment. But we do have to remember that nonpolar molecules can experience small disparities in their charge which is the Van der waal force. The molecule will be polar if it has a p...
by Lily Benitez 2G
Sat Nov 17, 2018 9:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape vs electron geometry
Replies: 4
Views: 60

Re: Molecular shape vs electron geometry

The molecular shape doesn't take to account the lone pairs found on the central atoms, and thus results in the shape being the same. While electron geometry does take this into account and we know that lone pairs have a higher electron density so this changes the shape completely.
by Lily Benitez 2G
Sat Nov 17, 2018 9:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: No central atom
Replies: 7
Views: 135

Re: No central atom

Each N will have one lone pair and 2 bond pairs and this will result in a "bent" shape.
by Lily Benitez 2G
Sun Nov 11, 2018 9:39 pm
Forum: Trends in The Periodic Table
Topic: Atomic vs ionic radius
Replies: 4
Views: 158

Re: Atomic vs ionic radius

When it comes to the neutral atom both ionic and atomic radius is the same. But we know that many elements can lose or gain electrons converting them to anions or cations. We know that if an atom loses an electron the radius decreases, if the ion gains an electron the radius increases. This is where...
by Lily Benitez 2G
Sun Nov 11, 2018 9:34 pm
Forum: Bond Lengths & Energies
Topic: Drawing resonance structures?
Replies: 6
Views: 112

Re: Drawing resonance structures?

When asking for a structure they are usually looking for the one that is most stable. If the compound is neutral you will draw the one with an overall charge of zero. You can identify the charge by using formal charge.
by Lily Benitez 2G
Sun Nov 11, 2018 3:08 pm
Forum: Bond Lengths & Energies
Topic: Covalent Radius
Replies: 3
Views: 93

Re: Covalent Radius

When you have a covalent bond between atoms you can find the covalent radius. The distance between the two nuclei of the atoms will give you the diameter so you would have to divide by two. Atomic radius is just focusing on one atom.
by Lily Benitez 2G
Sun Nov 11, 2018 2:52 pm
Forum: Properties of Electrons
Topic: Polar vs Non polar
Replies: 11
Views: 381

Re: Polar vs Non polar

To figure out if something is polar or non polar we have to look at the dipole moments. If the dipole moments cancel each other out the compound is non polar. In contrast if there is a strong dipole moment the compound is polar.
by Lily Benitez 2G
Sun Nov 11, 2018 2:48 pm
Forum: SI Units, Unit Conversions
Topic: Bond length
Replies: 3
Views: 201

Re: Bond length

When it comes to bond lengths we need to know that single bonds are longer and weaker than single and triple bonds. When it comes to resonance we know that the electrons are delocalized causing partial bonds. So a compound can have both single and double bond characteristics.
by Lily Benitez 2G
Sun Nov 04, 2018 4:30 pm
Forum: Lewis Structures
Topic: 7th edition 2B.9
Replies: 4
Views: 47

Re: 7th edition 2B.9

When drawing the Lewis Structure for ionic bonds we have to remember that one atom is "giving away" its electron while the other is receiving it. And one atom will become positively charge while the other will become negatively charge and attract each other. That is why we don't draw the &...
by Lily Benitez 2G
Sun Nov 04, 2018 4:22 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energies
Replies: 2
Views: 53

Re: Ionization Energies

I don't think we need to know that for this midterm but you do need to know the periodic trend for ionization energy.
by Lily Benitez 2G
Sun Nov 04, 2018 4:10 pm
Forum: Lewis Structures
Topic: HW 3.39
Replies: 1
Views: 34

Re: HW 3.39

Potassium Hypochlorite (NaClO) is known has an ionic bond. It is composed of a potassium ion (Na+) and a hypochlorite ion (ClO-). So if we put that together we get Na+ [Cl--0]- plus the lone pairs around Cl and O to complete the octet.
by Lily Benitez 2G
Sun Nov 04, 2018 4:02 pm
Forum: Trends in The Periodic Table
Topic: 7th Edition 1F 11
Replies: 1
Views: 46

Re: 7th Edition 1F 11

This trend either increases or can decrease when going across a period, this all depends on the electron configuration of an atom. For example a half filled p sub-shell can be identified as more stable, carbon has higher electron affinity in comparison to nitrogen.
by Lily Benitez 2G
Sun Oct 28, 2018 9:23 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Equation
Replies: 2
Views: 94

Equation

When using the heisenberg indeterminacy equation do we use the radius or diameter for delta x?
by Lily Benitez 2G
Sun Oct 28, 2018 9:20 pm
Forum: DeBroglie Equation
Topic: De Broglie
Replies: 12
Views: 415

Re: De Broglie

You use it when the question asks you for a wavelength and the known object has a mass and velocity.
by Lily Benitez 2G
Tue Oct 23, 2018 10:05 pm
Forum: Photoelectric Effect
Topic: Wavelength Calculation
Replies: 2
Views: 138

Re: Wavelength Calculation

Thank you
by Lily Benitez 2G
Tue Oct 23, 2018 7:00 pm
Forum: Photoelectric Effect
Topic: Wavelength Calculation
Replies: 2
Views: 138

Wavelength Calculation

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km/s . (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 x 10^16 Hz. How much energy is require...
by Lily Benitez 2G
Sat Oct 20, 2018 11:41 pm
Forum: Properties of Light
Topic: Visible Light
Replies: 5
Views: 68

Visible Light

What is the wavelength range of visible light? I've seen many ranges but I don't know which one is correct.
by Lily Benitez 2G
Tue Oct 09, 2018 10:12 pm
Forum: Limiting Reactant Calculations
Topic: Percent Yield [ENDORSED]
Replies: 13
Views: 605

Percent Yield [ENDORSED]

I know that the equation for percent yield is Actual Yield/Theoretical Yield...but I still confused on which value is which. Can someone please explain the difference between actual and theoretical?
by Lily Benitez 2G
Tue Oct 09, 2018 8:58 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity
Replies: 4
Views: 245

Molarity

I have attempted this problem multiple times and keep getting the same answer; which is not one of the answer in the module. I have used the formula M1*V1=M2*V1. For M1 I got .211, V1 is .150L, V2 is .250L, and we are trying to find M2. Did I do a miscalculation? 5.00 g of KMnO4 is dissolved in a 15...
by Lily Benitez 2G
Sun Oct 07, 2018 10:52 pm
Forum: Molarity, Solutions, Dilutions
Topic: To find the amount of water used
Replies: 1
Views: 35

Re: To find the amount of water used

If you have already found both the initial and final you can use that formula. If you are missing one of the volumes you can use M1V1 = M2V2, M1 is the molarity (moles/Liters).
by Lily Benitez 2G
Sun Oct 07, 2018 10:46 pm
Forum: Significant Figures
Topic: knowing how many sig figs to use
Replies: 17
Views: 553

Re: knowing how many sig figs to use

What helps me when it comes to sig figs I usually put the numbers given into scientific notation. This helps when the numbers are too big or too small to tell the appropriate sig figs.
by Lily Benitez 2G
Sun Oct 07, 2018 10:43 pm
Forum: Empirical & Molecular Formulas
Topic: when to multiply empirical formula [ENDORSED]
Replies: 9
Views: 384

Re: when to multiply empirical formula [ENDORSED]

You multiply by the smallest possible value; that will give you a whole number.

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