Search found 116 matches

by Daria Azizad 1K
Tue Mar 10, 2020 6:22 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B acids and bases section
Replies: 2
Views: 42

Re: 14B acids and bases section

Since 14B acids and bases builds upon info from the 14a section, I think it would be useful to review it if necessary.
by Daria Azizad 1K
Tue Mar 10, 2020 6:19 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta g
Replies: 6
Views: 45

Re: delta g

I think based on the information you are given. If it isn't as standard temp, use g= delta h - t delta s.
by Daria Azizad 1K
Tue Mar 10, 2020 6:17 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: reaction mechanism
Replies: 2
Views: 25

Re: reaction mechanism

We can predict a potential pathway, but not verify any elementary steps as being the correct ones.
by Daria Azizad 1K
Tue Mar 10, 2020 6:15 pm
Forum: Second Order Reactions
Topic: 2nd Order Slope
Replies: 2
Views: 20

Re: 2nd Order Slope

The reverse reaction will be. Since concentration of a reactant decreases as a rxn progresses, 1/[R] will increase.
by Daria Azizad 1K
Tue Mar 10, 2020 6:13 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Angular dependence
Replies: 2
Views: 24

Re: Angular dependence

The angular dependence is taken into account by the pre-exponential factor, A, which you can think of as the likelihood/probability of a rxn happening based on a collision. So when A is large, k is larger, and when A is smaller, k is smaller because k and A are directly related thru the Arrhenius eqn.
by Daria Azizad 1K
Tue Mar 10, 2020 6:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Using Equilibrium constants to predict solubility
Replies: 4
Views: 52

Re: Using Equilibrium constants to predict solubility

The relationship btwn K and the constants is K= k/k', which means that when k is high, the rxn favors the products and when k' is high, the rxn favors the reactants.
by Daria Azizad 1K
Thu Mar 05, 2020 11:43 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: thermodynamically stable
Replies: 6
Views: 83

Re: thermodynamically stable

Thermodynamic stability can be identified by looking at delta G. Something stable will be in its lowest energy form and will therefore be unlikely to react.
by Daria Azizad 1K
Thu Mar 05, 2020 11:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Potentials
Replies: 4
Views: 63

Re: Standard Potentials

They are based on the reaction with the standard hydrogen electrode.
by Daria Azizad 1K
Thu Mar 05, 2020 11:39 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Cell potential
Replies: 6
Views: 78

Re: Cell potential

It will decrease the concentration. To find out how this affects cell potential, you can plug numbers into E=-RT/nF lnQ with alterations to Q. For instance, if the cathode's concentration decreases, cell potential will increase.
by Daria Azizad 1K
Thu Mar 05, 2020 11:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: same solutions in cell diagram
Replies: 2
Views: 33

Re: same solutions in cell diagram

They are in the same solution when they are all at either the anode or cathode. Commas denote same side and state. The straight line refers to different phases.
by Daria Azizad 1K
Thu Mar 05, 2020 11:33 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Electrode masses
Replies: 8
Views: 91

Re: Electrode masses

If you increase the mass of electrodes the battery will have a longer lifetime. Cell potential will not change
by Daria Azizad 1K
Thu Feb 27, 2020 11:10 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 part d
Replies: 2
Views: 33

Re: 6L.5 part d

Au (s) is the electrode. Even though it is submerged in solution, it has not dissociated and is therefore is solid.
by Daria Azizad 1K
Thu Feb 27, 2020 11:08 pm
Forum: Balancing Redox Reactions
Topic: Direction of Reaction
Replies: 3
Views: 52

Re: Direction of Reaction

Based on Q in the Nernst equation. If [P] > [R] then Ecell is negative. If [P] < [R] then Ecell is positive
by Daria Azizad 1K
Thu Feb 27, 2020 10:56 pm
Forum: Balancing Redox Reactions
Topic: 6K. 5b
Replies: 3
Views: 38

Re: 6K. 5b

Balance the electrons in the oxidation reaction because the stoichiometric coefficient applies to the # of e- as well
by Daria Azizad 1K
Thu Feb 27, 2020 10:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrolyte
Replies: 4
Views: 37

Re: Electrolyte

An electrolyte is a salt like KOH or NaCl. It completely ionizes in solution
by Daria Azizad 1K
Thu Feb 27, 2020 10:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L7 (b) HW
Replies: 3
Views: 59

Re: 6L7 (b) HW

Yeah I was a bit confused about how the oxidation numbers don't change, but it can be broken down to reduction and oxidation half reactions: reduction: 4e- + O2 + 2H2O --> 4OH- oxidation: 2H2O --> 4H+ + O2 + 2e- How do we know that O2 is involved? Like why is it not Red: 2H+ + 2e- -> H2 Oxid: 2OH- ...
by Daria Azizad 1K
Thu Feb 27, 2020 9:15 pm
Forum: Balancing Redox Reactions
Topic: Acidic/Basic Solutions
Replies: 3
Views: 39

Re: Acidic/Basic Solutions

I believe we will be given that information.
by Daria Azizad 1K
Sun Feb 23, 2020 10:29 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: platinum
Replies: 4
Views: 29

Re: platinum

Platinum is inert and won't interfere w the redox rxn. Other inert materials could be used as well, such as graphite.
by Daria Azizad 1K
Sun Feb 23, 2020 10:24 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n
Replies: 13
Views: 181

Re: n

Which eqn are you referring to? N is the number of moles, not R.
by Daria Azizad 1K
Sun Feb 23, 2020 10:06 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Positive Voltage
Replies: 2
Views: 16

Re: Positive Voltage

Yes, because its positive value means that delta G will be negative, therefore the rxn is spontaneous. If the standard potential is negative, that means the reverse rxn is spontaneous.
by Daria Azizad 1K
Sun Feb 23, 2020 10:01 am
Forum: Balancing Redox Reactions
Topic: Oxidation States
Replies: 7
Views: 58

Re: Oxidation States

Elements in Groups 1, 2, 6, and 7 generally will carry the same oxidation state as the charge of the cation/anion they form. Therefore, assigning their oxidation states first allows us to find the oxidation state of an unknown oxidation state. Also, knowing the charges of polyatomic cations and anio...
by Daria Azizad 1K
Sat Feb 15, 2020 9:58 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy
Replies: 12
Views: 259

Re: Enthalpy

A state function relies on initial and final values, not the pathway taken.
by Daria Azizad 1K
Sat Feb 15, 2020 9:46 pm
Forum: Calculating Work of Expansion
Topic: work = 0
Replies: 14
Views: 234

Re: work = 0

In a vacuum, there is nothing to push against, therefore no work is performed.
by Daria Azizad 1K
Sat Feb 15, 2020 9:42 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 4
Views: 43

Re: Van't Hoff Equation

The T cancels because it is in both numerator and denominator
by Daria Azizad 1K
Sat Feb 15, 2020 9:42 pm
Forum: Van't Hoff Equation
Topic: Constant
Replies: 3
Views: 33

Re: Constant

A good way to figure out which R to use it to see what units you need to cancel in order to get the desired units
by Daria Azizad 1K
Sat Feb 15, 2020 9:40 pm
Forum: Calculating the pH of Salt Solutions
Topic: How do you know if something is a salt solution?
Replies: 5
Views: 121

Re: How do you know if something is a salt solution?

A salt will dissociate into its constituent ions in water, so the ion that is an acid or base will act the same way as a normal acid/base and you will solve it the same way.
by Daria Azizad 1K
Sat Feb 15, 2020 9:35 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium
Replies: 15
Views: 137

Re: Equilibrium

At equilibrium, the system does not have a preference for the forward or reverse rxn, so neither would spontaneously occur
by Daria Azizad 1K
Wed Feb 12, 2020 9:57 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpy
Replies: 2
Views: 36

Re: Bond Enthalpy

Reactants have their bonds broken, which is endothermic, so it is positive. Products have their bonds formed, which is exothermic, thus negative.
by Daria Azizad 1K
Mon Feb 10, 2020 12:43 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4C.3
Replies: 1
Views: 31

Re: 4C.3

they give you the value for q, you can find Cv and Cp from the ideal gas heat capacity eqn, and you're given Ti, so you're just solving for Tf.
by Daria Azizad 1K
Mon Feb 10, 2020 12:38 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive Property
Replies: 3
Views: 38

Re: Intensive Property

Heat capacity is an intensive property because it depends on the amount of matter that you start with. Heat capacity is defined as the energy that it takes to raise 1mol of substance by 1 degree c, and it takes more energy to raise 1 mol of a complex molecule by 1 degree C than it does a simple one...
by Daria Azizad 1K
Mon Feb 10, 2020 12:37 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4D.3
Replies: 2
Views: 35

Re: 4D.3

Use the qcal= Ccal x delta T to get q, which is delta U because delta U is equal to q at constant volume
by Daria Azizad 1K
Mon Feb 10, 2020 12:36 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 4D7
Replies: 4
Views: 43

Re: HW 4D7

For gases, the change in enthalpy is defined by that equation. This is because when gas is produced work is done to clear the other gases so the enthalpy is lower than the internal energy. This is explained in detail on pg 274 in the textbook (4D.2) Where does that formula come from? Shouldn't nRT ...
by Daria Azizad 1K
Mon Feb 10, 2020 12:34 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: when to change sign of enthalpies
Replies: 7
Views: 81

Re: when to change sign of enthalpies

Flipping the sign accounts for flipping the equation because we have changed from an endo to exo or exo to endo rxn.
by Daria Azizad 1K
Mon Feb 10, 2020 12:32 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: gas constant
Replies: 3
Views: 40

Re: gas constant

Use the gas constant that properly aligns with those units.
by Daria Azizad 1K
Mon Feb 10, 2020 12:32 am
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: standard entropy meaning
Replies: 3
Views: 18

Re: standard entropy meaning

standard entropy is entropy at standard conditions, which is at a chosen temp (generally 25)
by Daria Azizad 1K
Mon Feb 10, 2020 12:31 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Midterm Review #12b
Replies: 3
Views: 51

Re: Midterm Review #12b

would the enthalpies for the reactants and products in steps 1 and 3 be both positive? or would reactants be positive and products be negative? if the calculation for q in step 1 is positive because final temp is higher than initial and in step 3 it is negative because final temp is lower than init...
by Daria Azizad 1K
Mon Feb 10, 2020 12:27 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: % dissociation
Replies: 5
Views: 45

Re: % dissociation

Calculate the amount of H+ and divide by orginal amount of acid then multiply by 100
by Daria Azizad 1K
Wed Feb 05, 2020 11:10 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4f.13
Replies: 1
Views: 35

Re: 4f.13

351.5K is the BP temp of ethanol, so you only have to calculate the entropy at the phase change, so delta S = delta H of vap / T at BP
by Daria Azizad 1K
Wed Feb 05, 2020 9:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy of formation
Replies: 2
Views: 29

Re: enthalpy of formation

Yes because all atoms that form diatomic molecules are in those molecules under standard conditions.
by Daria Azizad 1K
Wed Feb 05, 2020 9:01 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.9
Replies: 2
Views: 28

Re: 4F.9

P and V have an inverse relationship
by Daria Azizad 1K
Wed Feb 05, 2020 9:00 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: Microstates
Replies: 7
Views: 63

Re: Microstates

microstates/degeneracy is the number of positions a molecule/atom can occupy.
by Daria Azizad 1K
Wed Feb 05, 2020 8:58 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.1a
Replies: 4
Views: 49

Re: 4F.1a

Maggie Eberhardt - 2H wrote:can someone explain to me how the answer to this problem (0.341 J/Kxs) is positive even though the equation you use to solve it is -(rate of heat generation)/temperature = -100/293???

The body is generating heat, so delta H is positive for the surroundings.
by Daria Azizad 1K
Thu Jan 30, 2020 10:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Unit
Replies: 6
Views: 40

Re: Enthalpy Unit

No, other units can represent it, but we use kJ by convention.
by Daria Azizad 1K
Thu Jan 30, 2020 10:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: qp and qv
Replies: 8
Views: 73

Re: qp and qv

When volume is not constant, the gas is either expanding or compressing, so there is some work done. Therefore, that energy from work contributes to the delta H and must be factored in.
by Daria Azizad 1K
Thu Jan 30, 2020 10:08 pm
Forum: Phase Changes & Related Calculations
Topic: standard reaction enthalpy vs. standard enthalpy of formation
Replies: 7
Views: 212

Re: standard reaction enthalpy vs. standard enthalpy of formation

Reaction enthalpy is the enthalpy of the overall reaction, while enthalpy of formation corresponds to a specific element.
by Daria Azizad 1K
Thu Jan 30, 2020 10:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 4
Views: 52

Re: Calorimeter

The heat released by the chemical reaction will be equal to the heat absorbed by the calorimeter. So,
(mass of calorimeter) x (C of calorimeter) x (change in temp) = (mass of substance) x (Cs) x (change in temp)
by Daria Azizad 1K
Thu Jan 30, 2020 2:00 pm
Forum: Calculating Work of Expansion
Topic: Work equation
Replies: 5
Views: 40

Re: Work equation

Since energy is used to do work, the system is losing energy, and that loss is represented by the minus sign.
by Daria Azizad 1K
Tue Jan 21, 2020 8:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa, Ka, and strength of acid
Replies: 3
Views: 16

Re: pKa, Ka, and strength of acid

Since Ka is the ratio of products to reactants, and a product is H3O+, when the concentration of H3O+ is higher, the Ka will be higher.
by Daria Azizad 1K
Tue Jan 21, 2020 8:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature
Replies: 2
Views: 28

Re: Temperature

Endothermic:
R + heat <-> P

Exothermic:
R <-> P + heat

Adding heat in an endothermic rxn will push it right, and adding heat in an exothermic rxn will push it left
by Daria Azizad 1K
Tue Jan 21, 2020 8:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: partial pressure
Replies: 5
Views: 42

Re: partial pressure

There is also Pa or kPa, which has a more significant difference. I think if it is necessary to convert we will be given the conversion factor.
by Daria Azizad 1K
Tue Jan 21, 2020 8:03 pm
Forum: Administrative Questions and Class Announcements
Topic: Calculator
Replies: 4
Views: 59

Re: Calculator

I think they want us to have a non-programmable calculator, so any scientific calculator would be safe to bring.
by Daria Azizad 1K
Tue Jan 21, 2020 8:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6B.9
Replies: 2
Views: 30

Re: 6B.9

Yes, whenever the H+/OH- concentration is greater than 1, pH/pOH will be negative
by Daria Azizad 1K
Tue Jan 14, 2020 10:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Kw
Replies: 16
Views: 128

Re: Kw

Both, as they refer to the same thing.
by Daria Azizad 1K
Tue Jan 14, 2020 10:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to approximate
Replies: 5
Views: 52

Re: When to approximate

We should be able to approximate in binomials as well. If you approximate it or solve it fully out, you get the same value.
by Daria Azizad 1K
Tue Jan 14, 2020 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 8
Views: 74

Re: Autoprotolysis

ELu 1J wrote:It occurs naturally and emphasizes the amphoteric nature of water (the ability to both give and accept a proton).

The ability to accept and donate a proton is amphiprotic, while amphoteric is the ability to react with both acids and bases. :)
by Daria Azizad 1K
Tue Jan 14, 2020 9:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.H.3
Replies: 3
Views: 74

Re: 5.H.3

You would multiply the Ks of the two reactions that form the given reaction since you can think of their separate eq constants being combined into one equilibrium constant.
by Daria Azizad 1K
Tue Jan 14, 2020 9:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.19
Replies: 2
Views: 35

Re: 5I.19

To solve this problem, you need to make an ICE table. The initial concentrations of H2 and I2 can be found by dividing the number of moles by the volume of the flask. Then, we can find H2's equilibrium concentration by multiplying its initial value by 0.6. If we say that the concentration of H2 chan...
by Daria Azizad 1K
Sat Jan 11, 2020 9:48 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in pressure
Replies: 5
Views: 46

Re: Change in pressure

When pressure is increased due to compression (volume of container being changed), the equilibrium will shift to the side with less moles. If pressure is increased by adding a gas not involved in the reaction, the equilibrium will not change (as the concentrations of the gases involved in the rxn ar...
by Daria Azizad 1K
Sat Jan 11, 2020 9:42 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Response of Equilibria to Change
Replies: 3
Views: 56

Re: Response of Equilibria to Change

The concentration is the real reason why it is affected. When pressure increases, volume decreases, so concentration increases. For example, if pressure is doubled, then volume is Concentration=moles/(1/2)V=2mol/V. So, in this case, concentration would be doubled.
by Daria Azizad 1K
Sat Jan 11, 2020 9:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Thermodynamically Stable
Replies: 3
Views: 61

Re: Thermodynamically Stable

A quick way to determine which is more stable is to compare the K values: if K is high products are favored, and when K is low, reactants are favored. Whichever has a lower K value would favor the reactants more so than the other.
by Daria Azizad 1K
Sat Jan 11, 2020 9:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 3
Views: 44

Re: 5G.9

There would be different amounts of O2 and O3 because of the different concentrations. This ratio does not refer to the eq. constant, so they would not be the same.
by Daria Azizad 1K
Sat Jan 11, 2020 9:32 pm
Forum: Ideal Gases
Topic: Units of Pressure
Replies: 8
Views: 73

Re: Units of Pressure

Most likely the value we need will be provided, just check that the units in the constant match up with the pressure unit.
by Daria Azizad 1K
Thu Dec 05, 2019 2:05 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: determining stronger acid
Replies: 1
Views: 43

Re: determining stronger acid

Yes, there is a periodic trend insofar as electronegativity and atomic size play a role. Larger atoms bonded to H have weaker bonds, so they are stronger acids.
by Daria Azizad 1K
Thu Dec 05, 2019 2:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate Ligands
Replies: 2
Views: 63

Re: Polydentate Ligands

A ligand is polydentate if it can bind to a metal atom at more than one location. The best way to figure this out would be looking at the Lewis structure and seeing if it could orient itself in such a way that makes multiple bonds possible. For example, H2O is monodentate because its bent structure ...
by Daria Azizad 1K
Thu Dec 05, 2019 2:01 pm
Forum: Lewis Acids & Bases
Topic: Equilibrium Arrows for Acid/Base
Replies: 1
Views: 33

Re: Equilibrium Arrows for Acid/Base

When it is a strong acid or base, use a one-way arrow because it completely dissociates. With weak acids and bases, there is both dissociation and formation occurring, so use a two way arrow.
by Daria Azizad 1K
Thu Dec 05, 2019 2:00 pm
Forum: Air Pollution & Acid Rain
Topic: Acid rain
Replies: 2
Views: 106

Re: Acid rain

carbon dioxide + water -> carbonic acid
CO2 (g) + H2O (l) -> H2CO3 (aq)

sulfur dioxide and nitrogen oxides can also lead to acid rain:
SO2 + H2O -> H2SO4

2NO2 + H2O -> HNO3 + HNO2
by Daria Azizad 1K
Thu Dec 05, 2019 1:56 pm
Forum: Conjugate Acids & Bases
Topic: Hydrogen Question
Replies: 2
Views: 56

Re: Hydrogen Question

Not necessarily, removal of one hydrogen is the conjugate base of an acid. For instance, H2CO3 has the conjugate bases HCO3- and CO3 2-
by Daria Azizad 1K
Thu Dec 05, 2019 1:55 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number
Replies: 6
Views: 74

Re: coordination number

I generally approach these problems by first identifying what ligands are in the coordinate sphere, so for (a), the ligand is chlorine. Since we know that Cl has a -1 charge and that there are four of them, that means the charge of nickel plus the charge of the chlorines will equal the charge of the...
by Daria Azizad 1K
Sun Dec 01, 2019 7:36 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Weak vs. Strong Acids
Replies: 3
Views: 32

Re: Weak vs. Strong Acids

The strength or weakness of an acid depends on how much it dissociates in solution. When it does not 100% dissociate, it is not a strong acid or strong base.
by Daria Azizad 1K
Sun Dec 01, 2019 7:34 pm
Forum: Conjugate Acids & Bases
Topic: Difference
Replies: 2
Views: 51

Re: Difference

A conjugate acid is when a base takes a H+ ion and a conjugate base forms when an acid loses its H+ ion
by Daria Azizad 1K
Sun Dec 01, 2019 7:31 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordinate bonds
Replies: 1
Views: 34

Re: coordinate bonds

Yes, if a lone pair is covalently bonded to another atom, then both electrons being shared come from the same atom, and therefore it is a coordinate covalent bond.
by Daria Azizad 1K
Sun Dec 01, 2019 7:22 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH of Weak Acid and Bases
Replies: 4
Views: 67

Re: pH of Weak Acid and Bases

We can find the pH of a weak acid or base using its Ka or Kb value. Use the equilibrium equation to solve for the concentration of H+. Then, take the -log of that concentration.

The equilibrium expression would look like this:
Ka= [H+][A-] / [HA]
by Daria Azizad 1K
Sun Dec 01, 2019 7:14 pm
Forum: Lewis Acids & Bases
Topic: Lewis v. Bronsted
Replies: 2
Views: 33

Re: Lewis v. Bronsted

The Bronsted definition refers to the donation or acceptance of a H+ ion while the Lewis definition refers to the donation or acceptance of an electron pair. In this way, the Lewis definition is much broader and can include other species like transition metals being oxidized and reduced, while the B...
by Daria Azizad 1K
Mon Nov 25, 2019 11:45 pm
Forum: Sigma & Pi Bonds
Topic: Unhybridized Orbital vs Spin Pair?
Replies: 8
Views: 68

Re: Unhybridized Orbital vs Spin Pair?

Also, the unhybridizied orbital is lower energy than the hybridized orbital, and electrons will go to the lowest energy state possible.
by Daria Azizad 1K
Mon Nov 25, 2019 11:19 pm
Forum: Naming
Topic: 9C3d
Replies: 4
Views: 78

Re: 9C3d

The OH2 is just to emphasize that the lone pair on the oxygen atom is what is coordinate to the central metal atom. Both are technically correct though.
by Daria Azizad 1K
Tue Nov 19, 2019 2:42 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: H2SeO4
Replies: 2
Views: 33

Re: H2SeO4

Tetrahedral shapes will never be nonpolar if there are different atoms bonded, even though the way we draw it in 1D makes it seem like it.
by Daria Azizad 1K
Tue Nov 19, 2019 2:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Question 2F3 part b
Replies: 3
Views: 43

Re: Question 2F3 part b

I think that both the structure w/ two double bonds and the structure w/ one double bond and one single bond are acceptable, so they are just giving answers for both.
by Daria Azizad 1K
Tue Nov 19, 2019 9:09 am
Forum: Lewis Structures
Topic: Octet Rule
Replies: 7
Views: 253

Re: Octet Rule

Formal charge is an indicator of stability, so considering the formal charge of a bonded atom is useful in determining whether or not it will break the octet rule. If breaking the octet rule results in a FC=0, it is likely more stable, and therefore more likely to be the correct lewis structure.
by Daria Azizad 1K
Tue Nov 19, 2019 9:07 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: States and Intermolecular forces
Replies: 4
Views: 40

Re: States and Intermolecular forces

Yes, solids have higher intermolecular forces, which is why we can think of the molecules composing a solid as being held together more tightly than those of a liquid or gas. A good way to remember this is to think about the Halogens and how F, the least polarizable of the group, is a gas, while Iod...
by Daria Azizad 1K
Tue Nov 19, 2019 9:01 am
Forum: Electronegativity
Topic: H-bonding Question
Replies: 2
Views: 125

Re: H-bonding Question

Yes, because of the alcohol group, there is H-bonding. For a molecule to have H-bonding, hydrogen must be bonded to O, N, or F, and those atoms must also have a lone pair.
by Daria Azizad 1K
Thu Nov 14, 2019 2:37 pm
Forum: Dipole Moments
Topic: question 3f.5
Replies: 3
Views: 48

Re: question 3f.5

Since Iodine is bigger, it has more electrons and outer valence electrons experience shielding from the positively charged nucleus. Thus, iodine is more polarizable than chlorine. This trend holds true as you move down the group. For BP, intermolecular attractions are more important than intramolecu...
by Daria Azizad 1K
Thu Nov 14, 2019 2:33 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: How to remember strength of different intermolecular forces
Replies: 5
Views: 58

Re: How to remember strength of different intermolecular forces

You can make a visual model of the intermolecular attractions by drawing the Lewis structures. Based on how close the electrons or nucleus of one molecule/atom can get to another nucleus or electron pair, you can distinguish what will be stronger. For instance, H forms Hydrogen bonds with lone pairs...
by Daria Azizad 1K
Thu Nov 14, 2019 2:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electrons
Replies: 9
Views: 104

Re: Electrons

Emma Joy Schaetz 1E wrote:Is this always true?


Yes, this is always true, as electrons will always be negatively charged and thus repel one another. Minimizing repulsion will always result in more stability.
by Daria Azizad 1K
Wed Nov 13, 2019 10:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR usage
Replies: 5
Views: 47

Re: VSEPR usage

Yes, molecular shape affects intermolecular interactions, as it influences how closely together they can get, or how close another molecule or atom can get to the central atom. For example, linear molecules can pack more closely together than tetrahedrals. Also, if a central atom is attached to four...
by Daria Azizad 1K
Wed Nov 13, 2019 10:33 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 moment clarification
Replies: 6
Views: 53

Re: dipole moment clarification

Dipole moments are describing intermolecular forces. As the electron distribution in one molecule forms areas of partial negative charge and areas of partial positive charge, it influences the partial charges in another molecule due to repulsive forces. Polar molecules have a permanent dipole, there...
by Daria Azizad 1K
Sat Nov 09, 2019 1:02 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: instantaneous dipoles
Replies: 3
Views: 41

Re: instantaneous dipoles

Number of electrons and shape of the molecule are often interrelated, as a molecule with more electrons will be larger. When comparing electrons with similar numbers of electrons, then shape will likely be a determining factor.
by Daria Azizad 1K
Sat Nov 09, 2019 12:57 pm
Forum: Resonance Structures
Topic: 2.7 - How to determine main structure if formal charges are equal?
Replies: 2
Views: 44

Re: 2.7 - How to determine main structure if formal charges are equal?

Usually, it is best to have differing FC side by side (like a -1 next to +1) rather than the same FC side by side (like +1 next to +1) because it is unlikely that there would be two same charge centers in close proximity due to repulsive forces.
by Daria Azizad 1K
Sat Nov 09, 2019 10:06 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: 3F.1
Replies: 1
Views: 36

Re: 3F.1

The central Se atom is single bonded to two OH groups and double bonded to two O. The OH groups will be polar w/ partial positives on H and partial negatives on O. Also, since the electron distribution is different for the single and double bonds, some areas on the molecule will “concentrate” more e...
by Daria Azizad 1K
Sat Nov 09, 2019 9:55 am
Forum: Dipole Moments
Topic: Hydrogen Bonds
Replies: 6
Views: 64

Re: Hydrogen Bonds

Since it is bonded to N, O, or F, which are highly electronegative, H’s one electron will be pulled away from it. So that means H is basically just a proton and therefore negatively charged atoms will be highly attracted to it.
by Daria Azizad 1K
Tue Nov 05, 2019 7:59 pm
Forum: Electronegativity
Topic: Homework Question 2D.5 Part a
Replies: 2
Views: 49

Re: Homework Question 2D.5 Part a

Larger atoms in bonds have more covalent character than smaller atoms (due to shielding and distance from nucleus increase). Since Iodine is larger, HI will have more covalent character.
by Daria Azizad 1K
Thu Oct 31, 2019 2:20 pm
Forum: Electronegativity
Topic: Electronegativity difference
Replies: 2
Views: 30

Re: Electronegativity difference

If we are expected to use exact electronegativities, I believe the values will be provided. Without those values, we can make assumptions as to the electronegativities of atoms based on periodic trends. As you move up and right, electronegativity increases. Therefore, we can assume the electronegati...
by Daria Azizad 1K
Thu Oct 31, 2019 2:16 pm
Forum: Molarity, Solutions, Dilutions
Topic: Help with Textbook problem G.7
Replies: 1
Views: 168

Re: Help with Textbook problem G.7

Multiply the percent of KNO3 by the total mass of the solution:

510 x 0.0545 = 27.8 g KNO3

Since the components of the solution are KNO3 and water, the remaining mass will be that of water.

510-27.8= 482.2g H2O
by Daria Azizad 1K
Thu Oct 31, 2019 2:13 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 57

Re: Formal Charge

No, charge will always be a whole number. Whenever we divide by two in the FC equation, the numerator will be an even number, as it refers to pairs of electrons.
by Daria Azizad 1K
Thu Oct 31, 2019 2:10 pm
Forum: Lewis Structures
Topic: 2B.7
Replies: 2
Views: 39

Re: 2B.7

Using formal charge is a helpful way to confirm the identity of E, as we know that an element w/ 5 VE is likely to be the central atom. We could also subtract the electrons accounted for by Cl and O from the total # of electrons and be left with 5 electrons. Since we are told that E is in period 3, ...
by Daria Azizad 1K
Thu Oct 31, 2019 2:02 pm
Forum: Lewis Structures
Topic: Radical
Replies: 2
Views: 28

Re: Radical

Species with an odd number of electrons have an unpaired electron. Take CH3 for example: there are 7 electrons total, so carbon will have 3 pairs and 1 single electron. This, by definition, makes it a radical. The converse is true, as even numbers of electrons form pairs.
by Daria Azizad 1K
Wed Oct 23, 2019 7:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.5
Replies: 4
Views: 40

Re: 2A.5

I believe the same thing happens for part d because the 6 s and p orbitals are farther from the nucleus and are therefore more "loosely" held. So when it becomes an ion, electrons are lost from there first.
by Daria Azizad 1K
Wed Oct 23, 2019 7:35 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 14
Views: 140

Re: Electronegativity

Electronegativity also decreases down the periodic table because as more shells are added, the more distant the positive nucleus is from other electrons it would attract; thus the electrostatic forces of attraction are weaker.
by Daria Azizad 1K
Wed Oct 23, 2019 7:21 pm
Forum: Photoelectric Effect
Topic: Hw Help 1B.5
Replies: 1
Views: 46

Re: Hw Help 1B.5

Electron diffraction gives evidence that EM radiation acts like a wave instead of a particle. Black body radiation and the atomic spectra both give evidence that energy is emitted/absorbed discretely (thus evidence of particle nature), however the photoelectric effect is what confirmed that EM radia...
by Daria Azizad 1K
Wed Oct 23, 2019 7:14 pm
Forum: Lewis Structures
Topic: Number of valence electrons
Replies: 3
Views: 49

Re: Number of valence electrons

Elements in the third period and after generally have exceptions to the octet rule where they can take on more electrons than eight. However, prior to that, H and He will not follow the octet rule, but rather the "duet rule" because they will only try to fill up their s orbital. Boron also...

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