Search found 102 matches

by Chris Tai 1B
Mon Mar 16, 2020 12:17 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 4
Views: 56

Re: Activation Energy

Catalysts can also be used to affect the activation energy that a reaction needs to proceed by lowering such activation energy. This is independent of the reaction and the catalyst is not consumed in the reaction itself.
by Chris Tai 1B
Mon Mar 16, 2020 12:13 pm
Forum: Van't Hoff Equation
Topic: Entropy
Replies: 2
Views: 155

Re: Entropy

This depends on which form of the Van't hoff equation you're using. You can use the van't hoff equation to indirectly solve for the enthalpy of a reaction over a given temperature range, since the equation relates two different equilibrium constants at two different temperatures with there being a f...
by Chris Tai 1B
Fri Mar 13, 2020 10:35 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre Equilibrium Approach
Replies: 1
Views: 27

Re: Pre Equilibrium Approach

The pre equilibrium approach is a method that is used to help determine the experimental rate law based on an observed rate law. We know that there is a fast step and a slow step, since there is likely an intermediate that is produced in between the two steps. If the early step is fast, and the late...
by Chris Tai 1B
Fri Mar 13, 2020 10:31 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Steady State Approach
Replies: 1
Views: 20

Re: Steady State Approach

Reactants are put into a mixture, and the moment the reaction starts, we measure the speed of the reaction at that specific, nearly instantaneous time point and then assume that this is the reaction rate for the reaction. However, we don't necessarily need to know this for the final, since we can us...
by Chris Tai 1B
Fri Mar 13, 2020 10:24 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order reaction
Replies: 4
Views: 86

Re: Order reaction

One easy way to determine the order of the reaction is to look at the rate law for the reaction. If there is one reactant, then the order of the reaction will be an order of one. If there are two reactants, then the reaction will be of order two. However, it's also important to look at the coefficie...
by Chris Tai 1B
Fri Mar 13, 2020 10:21 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 5
Views: 30

Re: Catalysts

There are two types of catalysts that are both not necessarily consumed within the reaction. The first is a homogeneous catalyst, which is a same phase catalyst. This form of catalyst is made up of the same starting materials, and the reaction typically occurs within solution. The second is a hetero...
by Chris Tai 1B
Fri Mar 13, 2020 10:19 pm
Forum: General Rate Laws
Topic: General Rate Law
Replies: 2
Views: 33

Re: General Rate Law

We can use the general rate law to determine several different items of general importance. The first of these includes a quite fantastical situation in which we are called to determine the order of such a reaction, in which we can simply take the however-many exponents and add up their given values...
by Chris Tai 1B
Fri Mar 13, 2020 10:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Concentration Cells
Replies: 2
Views: 23

Re: Concentration Cells

In a concentration cell, it's important to note that the substances on both sides of the cell will be the same, they'll just have different concentrations. The typical example is that of silver, where there is an anode on the right submerged in a solution of less concentrated aqueous silver, and a c...
by Chris Tai 1B
Fri Mar 13, 2020 9:08 pm
Forum: First Order Reactions
Topic: 7B.7
Replies: 1
Views: 50

Re: 7B.7

Since part b of the question is just asking for the time that it takes the concentration of substance to decrease to 1/4 its original concentration, you can just multiply the half life of the substance by 2. It will decrease to half of the concentration first (one half life) and then decrease to hal...
by Chris Tai 1B
Fri Mar 13, 2020 8:57 pm
Forum: First Order Reactions
Topic: 7B.1 mass of drug left in body
Replies: 2
Views: 48

Re: 7B.1 mass of drug left in body

Yes, the initial mass of the drug replaces the initial concentration in the rate law equation that you've provided. So, you could use this equation in 7B.1 to solve for how much drug (mass) is leftover. This will get you the correct answer.
by Chris Tai 1B
Fri Mar 13, 2020 8:54 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: U vs H
Replies: 15
Views: 269

Re: U vs H

Moreover, we can find that deltaU = qv, which makes sense because the volume is constant (no expansion work is being done), so the change in internal energy must solely be a result of the increase of energy inputted into the system qv at a constant volume. On the other hand, deltaH = qp, which can ...
by Chris Tai 1B
Fri Mar 13, 2020 4:30 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Identifying First and Second Order
Replies: 3
Views: 38

Re: Identifying First and Second Order

One easy way to determine the order of the reaction is to look at the rate law for the reaction. If there is one reactant, then the order of the reaction will be an order of one. If there are two reactants, then the reaction will be of order two. However, it's also important to look at the coefficie...
by Chris Tai 1B
Mon Mar 02, 2020 1:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7
Replies: 1
Views: 48

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 (b) H+(aq) + OH-(aq) -> H2O(l), the Brønsted neutralization reaction (c) Cd(s) + 2 Ni(OH)3(s) -> Cd(OH)2(s) + 2 Ni(OH)2(s), ...
by Chris Tai 1B
Mon Mar 02, 2020 1:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 2
Views: 35

Platinum

Under what circumstances should I include platinum in the cell diagram? When do I know it's on the side of the anode or on the side of the cathode, or both?
by Chris Tai 1B
Mon Mar 02, 2020 1:13 pm
Forum: Van't Hoff Equation
Topic: what does it do?
Replies: 13
Views: 247

Re: what does it do?

Could you elaborate a little more on how it's an indirect way to measure enthalpy, please? When using the Van't Hoff equation, we assume that the difference in enthalpy is considered to be the same, and we assume that the difference in entropy between reactants and products is also the same at thes...
by Chris Tai 1B
Mon Mar 02, 2020 1:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneity
Replies: 7
Views: 101

Re: Spontaneity

Spontaneous processes don't necessarily happen quickly, it just means that over time there is a tendency for that reaction to occur. The equation that relates spontaneity to the cell potential difference is deltaGknot = -nFEknot. This makes sense, because the more positive the E value of cell poten...
by Chris Tai 1B
Sun Mar 01, 2020 10:44 pm
Forum: Balancing Redox Reactions
Topic: 6K.5 part b
Replies: 4
Views: 59

6K.5 part b

Could someone walk me through how to set up the two redox reactions for part b of 6K.5? Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in basic solution. Identify the oxidizing agent and reducing agent in each reaction. ...
by Chris Tai 1B
Fri Feb 21, 2020 10:57 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: U vs H
Replies: 15
Views: 269

Re: U vs H

Moreover, we can find that deltaU = qv, which makes sense because the volume is constant (no expansion work is being done), so the change in internal energy must solely be a result of the increase of energy inputted into the system qv at a constant volume. On the other hand, deltaH = qp, which can b...
by Chris Tai 1B
Fri Feb 21, 2020 10:53 pm
Forum: Van't Hoff Equation
Topic: Entropy in Van't Hoff Equation
Replies: 3
Views: 51

Re: Entropy in Van't Hoff Equation

The reason we assume the entropy is constant is not that we think that the entropy is the same value, but that the difference in that entropy between reactants and products is the same at two different temperatures. The entropy may indeed be higher or lower at given temperatures, but the difference ...
by Chris Tai 1B
Fri Feb 21, 2020 10:51 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: units for entropy with Boltzmann's constant
Replies: 2
Views: 112

Re: units for entropy with Boltzmann's constant

When W is Watts, the units are J/s; however, when W is the degeneracy, I don't really think there are units for it. This is definitely confusing because Watts are symbolic of units, whereas W in the context of entropy is symbolic of entropy. Hence, this makes sense, because if Boltzmann's constant i...
by Chris Tai 1B
Fri Feb 21, 2020 10:48 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneity
Replies: 7
Views: 101

Re: Spontaneity

Spontaneous processes don't necessarily happen quickly, it just means that over time there is a tendency for that reaction to occur. The equation that relates spontaneity to the cell potential difference is deltaGknot = -nFEknot. This makes sense, because the more positive the E value of cell potent...
by Chris Tai 1B
Fri Feb 21, 2020 10:44 pm
Forum: Van't Hoff Equation
Topic: what does it do?
Replies: 13
Views: 247

Re: what does it do?

When using the Van't Hoff equation, we assume that the difference in enthalpy is considered to be the same, and we assume that the difference in entropy between reactants and products is also the same at these two different temperatures. The reason this is valuable is because it enables us to show t...
by Chris Tai 1B
Fri Feb 21, 2020 10:41 pm
Forum: Calculating Work of Expansion
Topic: when work is 0
Replies: 5
Views: 120

Re: when work is 0

In a reversible process, work doesn't necessarily have to be 0. If anything, the amount of work that a system can produce in a reversible process is greater than in an irreversible process, because the external pressure is slowly decreasing to a specific value, rather than being constant the entire ...
by Chris Tai 1B
Fri Feb 21, 2020 10:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concepts
Replies: 3
Views: 38

Re: Concepts

This can also be related to the spontaneity of a reaction. Given a redox reaction in a battery at a constant temperature and pressure, deltaG = -nFE, and for standard conditions, deltaGknot = -nFEknot. As stated, the "maximum cell potential is directly related to the free energy difference betw...
by Chris Tai 1B
Fri Feb 21, 2020 10:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Why is Plt and Iron on the same side of the cell diagram??
Replies: 2
Views: 34

Re: Why is Plt and Iron on the same side of the cell diagram??

Platinum, in this instance, represents an inert conductor that is the metal electrode used to transfer electrons. Iron is merely in the aqueous solution in the second, reduction cell. The reason Fe3+(aq) and Fe2+(aq) are on the same side of the salt bridge is because Fe3+ is being reduced to Fe2+ vi...
by Chris Tai 1B
Fri Feb 21, 2020 10:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Ways to Calculate Standard Cell Potentials
Replies: 3
Views: 58

Re: Ways to Calculate Standard Cell Potentials

Concerning the second method of calculating standard cell potentials - When you get the value of the standard cell potential, you'll always get a positive E value because the reduction of an element is spontaneous. However, some of the elements are oxidized, and you often won't find a standard cell ...
by Chris Tai 1B
Fri Feb 21, 2020 10:30 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Balancing redox reactions
Replies: 2
Views: 33

Re: Balancing redox reactions

Specifically when you're balancing chemical equations, it's goo to work with an example. Say you have Al(s) + MnCl2(aq) -> AlCl3(aq) + Mn(s). One of the things to recognize is that we really have manganese and aluminum cations here when they dissociate in aqueous solution into their counterparts of ...
by Chris Tai 1B
Fri Feb 21, 2020 10:22 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Relationship between Gibbs free energy and E
Replies: 2
Views: 36

Re: Relationship between Gibbs free energy and E

The (delta)G^o = -nFE^o equation is one of the equations that relates Gibbs free energy to E. I like to think of it as the value of E affecting the spontaneity of a reaction, instead of the spontaneity of the reaction affecting the value of E (althought I suppose this is a potential way of interacti...
by Chris Tai 1B
Fri Feb 21, 2020 9:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 4
Views: 47

Re: Salt Bridge

Over time, the electrons flow from one side of the cell to the other side, and the cell eventually reaches an equilibrium where the potential difference of the cell does not have a positive value. If there isn't a positive value to this difference, then the cell no longer really has the potential to...
by Chris Tai 1B
Fri Feb 21, 2020 9:42 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Delta G and spontaneous process
Replies: 2
Views: 32

Re: Delta G and spontaneous process

There's probably not a specific cutoff for what distinguishes a "large dG cutoff" as opposed to a "not-so-large dG cutoff"; I think a lot of this is contextual, and what matters most is the understanding that a negative dG value means that the reaction will occur spontaneously, r...
by Chris Tai 1B
Fri Feb 21, 2020 9:39 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Equation
Replies: 1
Views: 33

Re: Equation

This equation is derived from a litany of other steps and equations. First, we know that deltaGknot = -RTlnK, and that deltaGknot = deltaHknot - TdeltaSknot. So, substituting each equation in for deltaGknot, we get that -RTlnK = deltaHknot - TdeltaSknot. Next, if we know that deltaHknot is some spec...
by Chris Tai 1B
Fri Feb 21, 2020 9:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: dG vs dG knot
Replies: 2
Views: 38

Re: dG vs dG knot

DeltaG is the actual value of the change in free energy in a given chemical reaction. This value is determined by the equation deltaG = dGknot + RTlnQ, where Q is the ratio of products to reactant concentration. If there is much more reactants, then it's more likely that the deltaG value will be sma...
by Chris Tai 1B
Fri Feb 21, 2020 9:28 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: How to determine n in the Nernst Equation/Gibbs Free Energy Equation
Replies: 1
Views: 29

Re: How to determine n in the Nernst Equation/Gibbs Free Energy Equation

The "n" in the Nernst equation represents the amount of moles of electrons that are present. When this is multiplied by Farraday's constant, one can find the total charge of that given amount of moles of electrons. The n in the Gibbs Free Energy represents the amount of moles of a given su...
by Chris Tai 1B
Mon Feb 03, 2020 11:09 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: overall definitions
Replies: 4
Views: 46

Re: overall definitions

Here are some of the important ones - deltaT = change in temperature deltaS = change in entropy deltaH = change in enthalpy deltaU = change in internal energy deltaV = change in volume deltaP = change in pressure W = work The other W = degeneracy, which helps you find entropy Csp = specific heat cap...
by Chris Tai 1B
Mon Feb 03, 2020 11:03 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.11
Replies: 5
Views: 50

4A.11

A calorimeter was calibrated with an electric heater, which supplied 22.5 kJ of energy as heat to the calorimeter and increased the temperature of the calorimeter and its water bath from 22.45 8C to 23.97 8C. What is the heat capacity of the calorimeter? The equation q = nCdeltaT seems especially re...
by Chris Tai 1B
Wed Jan 29, 2020 11:04 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 4A.7
Replies: 3
Views: 32

4A.7

(a) Calculate the heat that must be supplied to a copper kettle of mass 400.0 g containing 300.0 g of water to raise its temperature from 20.0 8C to the boiling point of water, 100.0 8C. (b) What percentage of the heat is used to raise the temperature of the water? Could someone help me walk through...
by Chris Tai 1B
Wed Jan 29, 2020 10:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 4A.3 part c
Replies: 4
Views: 62

4A.3 part c

Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump is 3.0 cm and the pump is depressed 20. cm with a pressure of 2.00 atm. (c) What is the change in internal energy of the system? How do we approach part c with the information given? I thought since heat was...
by Chris Tai 1B
Sun Jan 26, 2020 7:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's law
Replies: 2
Views: 22

Re: Hess's law

If we want to apply Hess's law to this situation, we're typically given the change in enthalpy (deltaH) for both of the reactions independently. For the reaction N2(g) +O2(g) -> 2NO(g), deltaH = 180kJ For the reaction 2NO(g) + O2(g) -> 2NO2 (g), delta H = -112 kJ So, using the logic above to combine...
by Chris Tai 1B
Sun Jan 26, 2020 7:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 3
Views: 21

Re: Enthalpy

To build off of this, in thermochemistry the state property of enthalpy is often used, where we care most about the change in enthalpy (deltaH). Through this state property, we can determine whether a reaction is exothermic (deltaH is negative and releases heat) or endothermic (deltaH is positive an...
by Chris Tai 1B
Sun Jan 26, 2020 7:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Weak acid/base
Replies: 14
Views: 158

Re: Weak acid/base

The best way to determine whether an acid or base is weak is to memorize all the strong acids and bases and see if that acid is strong. If it's not strong, it's a weak acid or base. The strong acids are HBr, HClO4, H2SO4, HNO3, HCl, and HI. SImilar logic can be applied to the bases. The strong bases...
by Chris Tai 1B
Sun Jan 26, 2020 7:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy
Replies: 3
Views: 35

Re: Standard Enthalpy

Standard reaction enthalpy (deltaH) is the enthalpy of the reaction that occurs when all the reactants and products are in their standard state at 1 atmosphere. Standard enthalpy of formation (deltaHf) is the standard reaction enthalpy (deltaH) for the formation of one mole of a substance from its e...
by Chris Tai 1B
Sun Jan 26, 2020 7:41 pm
Forum: Phase Changes & Related Calculations
Topic: Delta H
Replies: 3
Views: 22

Re: Delta H

It depends on the question. If the question wants you to use deltaH to find something like temperature, deltaS (change in entropy), or deltaG (change in gibbs free energy), then it'll most likely be given to you or easily derivable. However, if the question wants you to find deltaH itself, then you'...
by Chris Tai 1B
Fri Jan 17, 2020 5:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong or weak acid?
Replies: 5
Views: 52

Re: Strong or weak acid?

The best way to know which acids are weak are to know which acids are strong. Everything that isn't a strong acid is essentially a weak acid. The strong acids are HBr, HClO4, H2SO4, HNO3, HCl, and HI. SImilar logic can be applied to the bases. The strong bases are all the hydroxides and the ones tha...
by Chris Tai 1B
Fri Jan 17, 2020 5:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5.35
Replies: 1
Views: 39

Re: Problem 5.35

The kPa, which is kilopascals, has to be converted to atmospheres. Since 1 kPa = 0.00987 atm, the book is just dividing by 100 as a shortcut to complete this conversion.
by Chris Tai 1B
Fri Jan 17, 2020 4:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Table 5G.2 K vs Kc
Replies: 1
Views: 23

Table 5G.2 K vs Kc

In table 5G.2, there are values for both K and Kc. In what instance would we use K, and in what instance would we use Kc instead?
by Chris Tai 1B
Fri Jan 17, 2020 4:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 3
Views: 28

5.33

Dissociation of a diatomic molecule, X2(g) <-> 2 X(g) occurs at 500 K. The equilibrium state of the reaction is shown in 1 and the equilibrium state in the same container after a change has occurred is shown in 2. Which of the following changes will produce the composition shown? (a) Increasing the ...
by Chris Tai 1B
Fri Jan 17, 2020 4:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Homework question 5J.5
Replies: 3
Views: 34

Re: Homework question 5J.5

In part d of this question, the equation produced is actually 2HD(g)⇌H2(g)+D2(g) instead of 2HD(g)+H2(g)⇌D2(g), which makes sense since the equation is now balanced. I'm not entirely sure how all the inert gas/noble gas stuff affects the way that the reactants/products shift in the event of higher p...
by Chris Tai 1B
Mon Jan 13, 2020 10:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw and H3O/OH concentrations
Replies: 5
Views: 46

Re: Kw and H3O/OH concentrations

When the concentrations of H30+ and OH- are the same in a given water, they are quite small and equivalent at 10^-7 M each. This leads to a pH of 7, since -log(10^-7) is 7. The reason there exist these concentrations of H30+ and OH- is because due to chance, water may as an amphiprotic compound form...
by Chris Tai 1B
Fri Jan 10, 2020 4:52 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5I.13
Replies: 1
Views: 50

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...
by Chris Tai 1B
Wed Jan 08, 2020 11:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.3
Replies: 4
Views: 55

5H.3

Use the information in Table 5G.2 to determine the value of K at 300 K for the reaction 2 BrCl(g) + 1 H2(g) <-> Br2(g) + 2 HCl(g).

Is there a way to determine the value of K given this table? If so, how?
by Chris Tai 1B
Sun Dec 08, 2019 3:53 pm
Forum: Bronsted Acids & Bases
Topic: NH3
Replies: 5
Views: 142

Re: NH3

NH3 is more complicated since it can act as both an acid and a base, just like water. If it donates a proton, it becomes NH2-, and if it accepts a proton, it becomes NH4+. So, NH3 is technically amphiprotic, meaning it's hard to determine if it'll always be a base (it depends on the solution it's in).
by Chris Tai 1B
Sun Dec 08, 2019 10:54 am
Forum: Biological Examples
Topic: porphyrin
Replies: 3
Views: 119

Re: porphyrin

A porphyrin ring is one that completely surrounds an atom (like a transition metal) and often forms coordinate covalent bonds with it. For instance, in the heme complex, the iron metal atom is surrounded by a porphyrin ring, where four different nitrogen atoms form coordinate covalent bonds with it....
by Chris Tai 1B
Sun Dec 08, 2019 10:51 am
Forum: Biological Examples
Topic: en and edta
Replies: 5
Views: 127

Re: en and edta

I think it would also be good to know why en is bidentate and why edta is hexadentate. For ethylenediamine (en), the two amine groups on the ends of the molecule can both function as ligands, which means en can create a chelating ligand ring around a transition metal, and is bidentate because it att...
by Chris Tai 1B
Wed Dec 04, 2019 1:06 pm
Forum: Bronsted Acids & Bases
Topic: Strong vs Weak Acids (6C.19)
Replies: 2
Views: 52

Strong vs Weak Acids (6C.19)

Decide which acid in each of the following pairs is the stronger and explain why: (a) HF or HCl; (b) HClO or HClO2; (c) HBrO2 or HClO2; (d) HClO4 or H3PO4; (e) HNO3 or HNO2; (f) H2CO3 or H2GeO3.

Could someone provide brief justifications for which acid is stronger in each example?
by Chris Tai 1B
Tue Dec 03, 2019 5:52 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.3
Replies: 2
Views: 63

6B.3

A careless laboratory technician wants to prepare 200.0 mL of a 0.025 m HCl(aq) solution but uses a volumetric flask of volume 250.0 mL by mistake. (a) What would the pH of the desired solution have been? (b) What will be the actual pH of the solution as prepared? For part a, I started by multiplyin...
by Chris Tai 1B
Tue Dec 03, 2019 5:40 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.1
Replies: 3
Views: 94

6B.1

The molar concentration of HCl in hydrochloric acid is reduced to 12% of its initial value by dilution. What is the difference in the pH values of the two solutions?

What equations would I use to set up this problem?
by Chris Tai 1B
Mon Dec 02, 2019 8:42 pm
Forum: Amphoteric Compounds
Topic: 6A.17
Replies: 4
Views: 128

6A.17

State whether the following oxides are acidic, basic, or amphoteric: (a) BaO; (b) SO3; (c) As2O3; (d) Bi2O3.

Why is b acidic? Doesn't the molecule have to have a H+ to donate in order for it to be acidic?
Could someone also provide a examples of c and d reacting in an amphoteric manner?
by Chris Tai 1B
Wed Nov 27, 2019 8:16 pm
Forum: Hybridization
Topic: single vs double vs triple bonds
Replies: 4
Views: 55

single vs double vs triple bonds

Why doesn't the number of bonds affect which hybrid orbital is formed? For instance, in ethylene c2h4, why is the double bond in between the carbons just two sp^2 hybrid orbitals instead of two individual sp^3 orbitals (since there are four bonds formed by carbon in total)?
by Chris Tai 1B
Wed Nov 27, 2019 8:11 pm
Forum: Hybridization
Topic: 2.45
Replies: 1
Views: 41

2.45

Consider the bonding in H2C=CHCHO. (a) Draw the most important Lewis structure. Include all nonzero formal charges. (b) Identify the composition of the bonds and the hybridization of each lone pair—for example, by writing sigma(H1s,C2sp^2 ). for part b, why is the sigma bond sigma(C2sp,O2p^2) while ...
by Chris Tai 1B
Wed Nov 27, 2019 8:06 pm
Forum: Hybridization
Topic: Hybridized orbital number
Replies: 1
Views: 44

Hybridized orbital number

How do you determine whether the hybridization of the valence electrons has a 2 compared to 3 in front of it? For instance, why is the bond between the carbon and hydrogen sigma(H1s^2, C2sp^2) instead of sigma(H1s^2, C3sp^2)? Could someone give me an example of an atom that forms 3sp^2 or 3sp^3 hybr...
by Chris Tai 1B
Wed Nov 27, 2019 7:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.29
Replies: 3
Views: 49

Re: 2E.29

Because the third isomer in this drawing has the chlorines on opposite sides of the "benzene" ring, those chlorine bonds are indeed polar as they are connected to a single carbon, but the molecule as a whole is not polar because the dipole moments created by those two opposite chlorine can...
by Chris Tai 1B
Wed Nov 27, 2019 7:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.25
Replies: 2
Views: 44

Re: 2E.25

Be careful when determining whether a molecule is polar or nonpolar - it matters if the dipole moments cancel or not. The bonds within a molecule may be polar, but the molecule as a whole may be nonpolar if those polar dipole moments cancel. For instance, in CCl4, the dipole moments all cancel since...
by Chris Tai 1B
Wed Nov 27, 2019 7:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Atoms in the same plane
Replies: 4
Views: 58

Re: Atoms in the same plane

Even if the molecule is "bent" or "angular" the molecule as a whole should be found in a single plane. This is true for those "bent" shaped molecules, but also for molecules that are trigonal "planar" and square "planar" (the name suggests that they ...
by Chris Tai 1B
Wed Nov 27, 2019 6:59 pm
Forum: Hybridization
Topic: Unpaired electrons
Replies: 2
Views: 50

Re: Unpaired electrons

The reason there must be some hybridization in the orbitals is that it best fits the VSEPR model. If the valence electrons were only that of the p orbitals attached to carbon, then in the methane example the hydrogens would be attached to carbon at 90 degree angles from each other, which clearly vio...
by Chris Tai 1B
Wed Nov 27, 2019 6:56 pm
Forum: Hybridization
Topic: 2F.13
Replies: 3
Views: 55

Re: 2F.13

Before solving any part of this problem, you should try and create a lewis dot structure like the one shown above; then you can look at each of the individual carbons to determine the bond angles. For instance, because the first CH2 carbon is sigma bonded to two hydrogens and double bonded to anothe...
by Chris Tai 1B
Wed Nov 27, 2019 6:52 pm
Forum: Hybridization
Topic: PCl6
Replies: 3
Views: 83

Re: PCl6

The reason octahedral shapes need to have an extra two valence d electrons is because the p suborbitals can only hold up to three valence electrons in such a given orbital, so atoms like Xe and P must go into the d orbital regions (which mix with the preexisting s and p orbitals) to gain more valenc...
by Chris Tai 1B
Thu Nov 21, 2019 11:58 pm
Forum: Dipole Moments
Topic: Rod and Spherically Shaped Molecules
Replies: 3
Views: 55

Re: Rod and Spherically Shaped Molecules

One way to differentiate two molecules, assuming we don't know their shape, is to differentiate each through their name. For instance, two molecules have the same molecular formula, C5H12. However, one is called pentane where as the other is called 2, 2 dimethylpropane. Pentane is a rod shaped molec...
by Chris Tai 1B
Thu Nov 21, 2019 11:58 pm
Forum: Dipole Moments
Topic: Rod and Spherically Shaped Molecules
Replies: 3
Views: 55

Re: Rod and Spherically Shaped Molecules

One way to differentiate two molecules, assuming we don't know their shape, is to differentiate each through their name. For instance, two molecules have the same molecular formula, C5H12. However, one is called pentane where as the other is called 2, 2 dimethylpropane. Pentane is a rod shaped molec...
by Chris Tai 1B
Thu Nov 21, 2019 11:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Bond Angles for Shapes with Lone Pairs
Replies: 5
Views: 83

Re: VSEPR Bond Angles for Shapes with Lone Pairs

Those all look correct!
You can also think about shapes with more than two electron pairs, such as
AX2E3 linear, 180, or
AX3E3 t shaped, 90, or
AXE4 linear, 180 and so on
by Chris Tai 1B
Sat Nov 09, 2019 2:36 pm
Forum: Electronegativity
Topic: Electronegativity and hydrogen bonds (3F.11)
Replies: 2
Views: 59

Electronegativity and hydrogen bonds (3F.11)

Which of the following molecules are likely to form hydrogen bonds: (a) PH3; (b) HBr; (c) C2H4; (d) HNO2? Turns out only d would form hydrogen bonds with other molecules, is there a reason that HBr doesn't? I know hydrogen bonds are usually formed when the hydrogen is attached to a N O or F, but are...
by Chris Tai 1B
Sat Nov 09, 2019 2:24 pm
Forum: Dipole Moments
Topic: 3F.1
Replies: 1
Views: 23

3F.1

Identify the types of attractive intermolecular interactions that might arise between molecules of each of the following substances: (a) NH2OH; (b) CBr4; (c) H2SeO4; (d) SO2. Can someone walk me through parts B and C? Why wouldn't part b have dipole-dipole interactions (isn't Br way more electronega...
by Chris Tai 1B
Sat Nov 09, 2019 2:22 pm
Forum: Dipole Moments
Topic: London forces
Replies: 9
Views: 104

Re: London forces

The London force is widely considered universal because any molecule or atom that has electrons or an electron cloud will inevitably have moments where one side of the molecule is more negative than the other due to random electron movements in the cloud. This in turn causes the opposite side to be ...
by Chris Tai 1B
Wed Nov 06, 2019 3:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Mo and Ag exceptions
Replies: 4
Views: 220

Mo and Ag exceptions

Are Molybdenum and Silver also exceptions to filling the 5s shell just like Chromium and Copper are? So would the electron configuration for Mo be [Kr] 4d^5 5s^1 and for Ag be [Kr] 4d^10 5s^1?
by Chris Tai 1B
Wed Nov 06, 2019 11:53 am
Forum: Lewis Structures
Topic: Lewis acids vs Lewis bases
Replies: 3
Views: 46

Lewis acids vs Lewis bases

What is the difference between a Lewis acid and a Lewis base? What are some examples of Lewis acids and Lewis bases?
by Chris Tai 1B
Wed Nov 06, 2019 11:36 am
Forum: Photoelectric Effect
Topic: Original Purpose of the Photoelectric Experiment
Replies: 1
Views: 125

Original Purpose of the Photoelectric Experiment

What was the photoelectric experiment originally designed to do?
by Chris Tai 1B
Wed Nov 06, 2019 11:33 am
Forum: Photoelectric Effect
Topic: Intensity in Photoelectric Effect
Replies: 6
Views: 223

Re: Intensity in Photoelectric Effect

To build off this, intensity in the wave model is described as the amplitude of the waves. However, it photons are treated like packets of light, then increasing the amplitude of the "waves" will merely increase the number of same-energy level photon packets. The energy of the photons, tha...
by Chris Tai 1B
Mon Nov 04, 2019 8:14 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarisability vs Polarizing Power
Replies: 15
Views: 283

Polarisability vs Polarizing Power

What is the difference between Polarisability and Polarizing Power?
by Chris Tai 1B
Sat Nov 02, 2019 6:01 pm
Forum: Lewis Structures
Topic: Expanded Valence Shells
Replies: 3
Views: 36

Re: Expanded Valence Shells

For instance, an atom like Phosphorus can hold more electrons than just the octet that it gets, since it would fill up its 3p shell, next moving onto the 3d and the 4s shells. Phosphorus can do this because it is in the 3rd period of the table. This is much more difficult for atoms that are in a low...
by Chris Tai 1B
Sat Nov 02, 2019 5:53 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 69
Views: 1769

Re: Advice for studying

I would really recommend trying to do as many of the homework problems as you can, so that when you come across a concept or a problem that you're not sure to how to solve, you can either ask here on Chemistry Community or go back and read the textbook so that you solidify that base of knowledge for...
by Chris Tai 1B
Sat Nov 02, 2019 5:42 pm
Forum: Photoelectric Effect
Topic: 1.31
Replies: 2
Views: 56

Re: 1.31

The question is a bit tricky because it also doesn't give the work function in terms of joules, which is what you need to plug into the equation E(photon) = E(work function)+E(kinetic energy of e-). Rather, it's given in electronvolts: 2.93 electron volts. There are 1.60218x10^-19 J in 1 eV, so we c...
by Chris Tai 1B
Sat Nov 02, 2019 5:37 pm
Forum: Properties of Electrons
Topic: Speed of electromagnetic radiation
Replies: 2
Views: 131

Re: Speed of electromagnetic radiation

This speed is always the speed of light, which is about 3x10^8 m/s. The equation that we can use to find either wavelength or frequency of electromagnetic radiation is (wavelength)(frequency) = (speed of light).
by Chris Tai 1B
Sat Nov 02, 2019 5:35 pm
Forum: Properties of Light
Topic: Homework 1.3
Replies: 1
Views: 57

Re: Homework 1.3

Here's what you know: there are 2.4x10^21 photons, and the wavelength of each photon is 633 nm. Convert wavelength to meters - 633x10^-9 m. Find frequency using (wavelength, 633x10^-9)(frequency) = (speed of light, 3x10^8) to get frequency v = 4.739x10^14 You can find the energy per photon to be E =...
by Chris Tai 1B
Sun Oct 27, 2019 2:03 pm
Forum: Properties of Light
Topic: Value for C
Replies: 8
Views: 99

Re: Value for C

Typically in calculations, it should be alright to use 3.00x10^8 in place for the speed of light. This definitely depends on how precise you want your result to be.
by Chris Tai 1B
Sun Oct 27, 2019 1:59 pm
Forum: Resonance Structures
Topic: Multiple Resonant Structures
Replies: 2
Views: 21

Re: Multiple Resonant Structures

Having multiple resonance structures gives us more of an explanation for experimented observations, such as the different bond lengths between atoms in a given molecule. For instance, if a single bond in the molecule is 1 A and a double bond is 2 A but the molecule has several different resonance st...
by Chris Tai 1B
Tue Oct 22, 2019 11:17 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework Question 1E.9
Replies: 3
Views: 53

Re: Homework Question 1E.9

If the shell is 5s (due to the n=5 and l=0 values) then visually there cannot be any other orientations of the s orbitals. S orbitals are symmetric, as opposed to p d and f orbitals, which means they really only have one orientation. Because the value of ml reveals which orientation the orbital is i...
by Chris Tai 1B
Tue Oct 22, 2019 11:13 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.23
Replies: 2
Views: 43

Re: 1E.23

Here's some reasoning for why the numbers of unpaired electrons exist as they do: Ga: [Ar] 3d10 4s2 4p1 - 1 unpaired electron, because there's only one electron in the px subshell Ge: [Ar] 3d10 4s2 4p2 - 2 unpaired electrons, because there's one electron in the px subshell and one in the py subshell...
by Chris Tai 1B
Tue Oct 22, 2019 11:09 am
Forum: Trends in The Periodic Table
Topic: Periodic Trend Exceptions
Replies: 7
Views: 78

Re: Periodic Trend Exceptions

One such exception is the ionization energy for oxygen. Because atoms tend to prefer to have either full or half full shells, oxygen will prefer to have 3 electrons in the p orbital instead of having only one pair and two unpaired electrons. Conversely, Nitrogen is somewhat content with its half ful...
by Chris Tai 1B
Sun Oct 20, 2019 10:12 pm
Forum: Properties of Electrons
Topic: Electron Configuration
Replies: 4
Views: 82

Re: Electron Configuration

You can also think of this in terms of valence electrons. The 4s shells will contain electrons that are more likely to be lost, thus ionizing a particular atom. Since it's more probable for a 4s electron to be given up by an atom than a 3d electron, the 3d shell should come first in the sequence. Th...
by Chris Tai 1B
Fri Oct 18, 2019 3:34 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: d orbitals
Replies: 1
Views: 35

Re: d orbitals

Since d orbitals are present in a plane rather than along a line like p orbitals, we can use something like dxy to represent a d orbital that is in the xy plane. However, the lobes of the orbital aren't along the x and y axes, but rather in between the axes. Hence, the dxz and the dyz orbitals also ...
by Chris Tai 1B
Wed Oct 16, 2019 4:11 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D.25
Replies: 3
Views: 58

1D.25

Which of the following subshells CANNOT exist in an atom:
(a) 2d
(b) 4d
(c) 4g
(d) 6f
Why is 6f able to exist in an atom? I'm a bit confused since the f-block of the periodic table ends at 4f and 5f
by Chris Tai 1B
Mon Oct 14, 2019 3:39 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Problem 1B.27
Replies: 3
Views: 53

Re: Problem 1B.27

I also used delta v = 10, which got me a solution of delta x >= 6.6 x 10^-37. I think the answer key may be incorrect here since the change in velocity could vary from 0 m/s to 10 m/s, which has a clear difference of 10-0 = 10
by Chris Tai 1B
Mon Oct 14, 2019 2:51 pm
Forum: Photoelectric Effect
Topic: 1B.15
Replies: 2
Views: 46

1B.15

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6x10^3 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 3 1016 Hz. How much energy is required to...
by Chris Tai 1B
Sun Oct 13, 2019 4:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1A.15
Replies: 1
Views: 33

1A.15

In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. Which equation(s) would I use to solve this problem? I'm still a bit confu...
by Chris Tai 1B
Sun Oct 13, 2019 4:52 pm
Forum: Properties of Light
Topic: Quanta
Replies: 4
Views: 73

Re: Quanta

Quanta or quantum in Latin is "how much", indicating that it's more of an amount of something that lacks units. For instance, in the context of photons, these quanta can simply be "packets" as Max Planck suggested of energy. The effect of these packets can be observed by analyzin...
by Chris Tai 1B
Sun Oct 13, 2019 4:47 pm
Forum: SI Units, Unit Conversions
Topic: Unit conversion
Replies: 15
Views: 529

Re: Unit conversion

For an example of converting 50nm to Angstroms: A good way to think about it is what was said before; you could also first convert nm to m and then convert that to Angstroms (easiest to conceptualize in my head). So, 50nm = 50 x 10^-9 m Since every Angstrom is 10^-10 m, we divide 50 x 10^-9 m / 10^-...
by Chris Tai 1B
Wed Oct 09, 2019 3:32 pm
Forum: Balancing Chemical Reactions
Topic: H.25
Replies: 3
Views: 185

Re: H.25

Solving for the other phosphorus oxide, using a similar method: First find the percentage of oxygen present in the oxide; since 56.34% of the compound is phosphorus, 43.66% of the compound must be oxygen. If we pretend that we have 100g of this substance, then we know that 56.34 g would be phosphoru...
by Chris Tai 1B
Tue Oct 08, 2019 5:43 pm
Forum: Properties of Light
Topic: 1A.11 Question on Balmer and Lyman series
Replies: 2
Views: 51

1A.11 Question on Balmer and Lyman series

In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series or Lyman series, as shown in Fig. 1A.10). What is common to the lines within a series that makes grouping them together logical? Could someone help me understand w...
by Chris Tai 1B
Thu Oct 03, 2019 4:38 pm
Forum: Molarity, Solutions, Dilutions
Topic: Fundamentals #G25
Replies: 2
Views: 51

Fundamentals #G25

G.25 Practitioners of the branch of alternative medicine known as homeopathy claim that very dilute solutions of substances can have an effect. Is the claim plausible? To explore this question, suppose that you prepare a solution of a supposedly active substance, X, with a molar concentration of 0.1...
by Chris Tai 1B
Thu Oct 03, 2019 4:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: Help on HW: Fundamentals G5
Replies: 3
Views: 105

Re: Help on HW: Fundamentals G5

I would start by using the equation for molarity and go from there: Molarity = number of mols/volume for part a, we can find the numbers of mols of Na2CO3 by taking 2.111 grams and dividing it by the molar mass of Na2CO3, which is about 106. Hence, we get 2.111/106 = 0.01992 mol Na2CO3. To find the ...
by Chris Tai 1B
Thu Oct 03, 2019 9:15 am
Forum: Molarity, Solutions, Dilutions
Topic: Fundamental G.3 Concentration
Replies: 2
Views: 41

Re: Fundamental G.3 Concentration

I find it easiest to first convert the micromoles to moles (for me it's personal preference) so get 1.44x10^-6 moles of glucose. Then you can use the equation Molarity = mols/Volume to find the volume needed, and input the values you've found. Hence, 1.44x10^-6 moles / 1.25x10^-3 mol/L = V = 0.00115...

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