Search found 102 matches
- Thu Mar 12, 2020 11:50 am
- Forum: Balancing Redox Reactions
- Topic: Oxygen
- Replies: 12
- Views: 596
Re: Oxygen
O2 and O3 has an oxidation number of 0, but O in any other compound or molecule has an oxidation number of -2.
- Thu Mar 12, 2020 11:47 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: How to determine order
- Replies: 3
- Views: 232
Re: How to determine order
You can use the experimental method when they give you a table of concentrations of reactants for different experiments and their rates to cancel and find the order. You can use graphs if given: - first order should be a straight negative slope plotted over ln[A] vs. time - second should be a straig...
- Thu Mar 12, 2020 11:44 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Pre-Equilibrium
- Replies: 3
- Views: 280
Re: Pre-Equilibrium
You use the pre-equilibrium method when the earlier step is the fast step and the later step is a slow step. You can then think of the fast step as being almost at equilibrium and use that to solve.
- Thu Mar 12, 2020 11:41 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7b.3c - where did the ln come from?
- Replies: 6
- Views: 365
Re: 7b.3c - where did the ln come from?
If you use the equation ln[A] = -kt + ln[A]0 you can see this will happen. You should be subtracting over the ln[A]0 before dividing and with laws of natural logs, if you subtract two logs you are basically taking the natural log of the two divided so that's why you are dividing 0.085/0.153 and then...
- Thu Mar 12, 2020 11:38 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7A.11) 700K?
- Replies: 6
- Views: 449
Re: 7A.11) 700K?
Yes you ignore it. I got the answer without using it.
- Thu Mar 12, 2020 11:35 am
- Forum: First Order Reactions
- Topic: question 7b.5
- Replies: 3
- Views: 240
Re: question 7b.5
Make sure to convert the hours into seconds so the units match up correctly!
- Thu Mar 12, 2020 11:30 am
- Forum: General Rate Laws
- Topic: 7A.17
- Replies: 5
- Views: 353
Re: 7A.17
You just need two experiments that have the same concentration for both experiments so you can cancel them to find the order of the one with different concentrations.
- Thu Mar 12, 2020 11:26 am
- Forum: General Rate Laws
- Topic: Rate Determining Step
- Replies: 5
- Views: 331
Re: Rate Determining Step
The rate determining step is the slow step. You can think of it this way. If two runners are tied together, one who is a track star and one who has never run before, even if the track star can outrun the slower runner, they are prevented because they are tied together. They can only move as fast as ...
- Sat Mar 07, 2020 11:25 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 7D1
- Replies: 4
- Views: 281
Re: 7D1
What equation are they using in this problem?
- Sat Mar 07, 2020 11:24 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Where do we find the values for A?
- Replies: 5
- Views: 449
Where do we find the values for A?
Are the values for A given to us somewhere or is there a way to calculate them?
- Sat Mar 07, 2020 10:25 pm
- Forum: First Order Reactions
- Topic: how to know actual order
- Replies: 4
- Views: 366
how to know actual order
In 7B.3 it tells us that the reactions are all first order but in part c the reaction is 2A > B + C which I thought would be a second order reaction. Do we not use the coefficients to find the order of the reaction?
- Sat Mar 07, 2020 10:12 pm
- Forum: Second Order Reactions
- Topic: 7B.3
- Replies: 5
- Views: 409
Re: 7B.3
You write out the rate law for the first-order reaction, then you find that [A] decreased by .068M over 115 seconds as the rate, then you can plug in all the information you know, leaving the k constant as the only unknown since you know [A], the rate, and that the reaction is first-order, and solv...
- Sat Mar 07, 2020 9:48 pm
- Forum: First Order Reactions
- Topic: 7B.9
- Replies: 1
- Views: 179
7B.9
How do you do this problem or other problems similar to this when they give you only the initial concentration of the reactant and then a later concentration of a product? For the first-order reaction A > 3B + C, when initial concentration of A = 0.015 mol/L, the concentration of B increases to 0.01...
- Sat Mar 07, 2020 9:25 pm
- Forum: Second Order Reactions
- Topic: 7B.3
- Replies: 5
- Views: 409
7B.3
How do you do part c of this question.( i.e. how do you find concentration of A) Determine the rate constant for each of the following first- order reactions, in each case expressed for the rate of loss of A: c) 2A > B + C [A]0 = 0.153 mol/L after 115s the concentration of B rises to 0.034 mol/L
- Thu Mar 05, 2020 9:12 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6N.23
- Replies: 1
- Views: 163
6N.23
How do we know what can be used for electrodes based on the other metals given. (a) Suggest two metals that could be used for the cathodic protection of a titanium pipeline. (b) What factors other than relative positions in the electrochemical series need to be consid- ered in practice? (c) Often co...
- Sat Feb 29, 2020 7:56 pm
- Forum: Balancing Redox Reactions
- Topic: When to add H+ or H20
- Replies: 19
- Views: 2308
Re: When to add H+ or H20
This is how you balance for both: 1. determine the oxidation and reduction half reactions. 2. Balance both half reactions: a) Balance elements other than H or O b) Balance O elements by adding H2O molecules to match the number of O molecules you have. c) Balance H elements by adding H+ (aq) FOR BASE...
- Sat Feb 29, 2020 7:50 pm
- Forum: Balancing Redox Reactions
- Topic: Cell Diagrams
- Replies: 14
- Views: 902
Re: Cell Diagrams
It does matter.
The anode is always on the left and the cathode is on the right with a salt bridge symbolized by "||" in the middle.
The anode is always on the left and the cathode is on the right with a salt bridge symbolized by "||" in the middle.
- Sat Feb 29, 2020 7:48 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic and Basic solutions
- Replies: 11
- Views: 647
Re: Acidic and Basic solutions
YES! They are different. Here's what my TA said for the difference: 1. determine the oxidation and reduction half reactions. 2. Balance both half reactions: a) Balance elements other than H or O b) Balance O elements by adding H2O molecules to match the number of O molecules you have. c) Balance H e...
- Sat Feb 29, 2020 7:47 pm
- Forum: Balancing Redox Reactions
- Topic: Difference between balancing Basic and Acidic
- Replies: 3
- Views: 318
Re: Difference between balancing Basic and Acidic
This is how you balance for both: 1. determine the oxidation and reduction half reactions. 2. Balance both half reactions: a) Balance elements other than H or O b) Balance O elements by adding H2O molecules to match the number of O molecules you have. c) Balance H elements by adding H+ (aq) FOR BASE...
- Sat Feb 29, 2020 7:43 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/reducing agent
- Replies: 18
- Views: 992
Re: Oxidizing/reducing agent
An oxidizing agent is one that oxidizes and thereby gets reduced.
A reducing agent is one that reduces and thereby gets oxidized.
A reducing agent is one that reduces and thereby gets oxidized.
- Tue Feb 25, 2020 11:46 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode vs Anode
- Replies: 6
- Views: 419
Re: Cathode vs Anode
you can also use "AN OIL RIG CAT" which means oxidation is loss of electrons at the anode and reduction is gain of electrons at the cathode.
- Tue Feb 25, 2020 11:44 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potential
- Replies: 4
- Views: 277
Re: Standard Cell Potential
E naught is when the cell is at 1M, 1atm, and 25*C. E naught is standard cell potential.
- Tue Feb 25, 2020 11:43 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 4
- Views: 281
Re: Cell Diagrams
anode on the left
cathode on the right
separate phases by "|" going from solids on the outside to gases on the inside
cathode on the right
separate phases by "|" going from solids on the outside to gases on the inside
- Tue Feb 25, 2020 11:41 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: How to Order Cell Diagrams
- Replies: 2
- Views: 205
Re: How to Order Cell Diagrams
Anode is on the left, cathode is on the right separated by || (Salt bridge).
You separate phases by "|" putting solids on the outside and working in towards gases.
You separate phases by "|" putting solids on the outside and working in towards gases.
- Tue Feb 25, 2020 11:40 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: what is value of E°?
- Replies: 2
- Views: 153
Re: what is value of E°?
You just plug in the standard cell potential they give you into E* = E*(cath) -E*(an). So it would be the way you did it first if you are not changing any of the signs given in the table.
- Tue Feb 25, 2020 11:37 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.7, standard potential
- Replies: 1
- Views: 168
Re: 6M.7, standard potential
I'm not sure but you can also look at electronegativity of an atom. The lower the electronegativity the stronger reducing agent it will be because it will be losing electrons (oxidation).
- Tue Feb 25, 2020 11:27 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum on one side of galvanic diagram
- Replies: 3
- Views: 204
Platinum on one side of galvanic diagram
Why is Pt(s) only added on one side of a galvanic diagram sometimes. For example, in 6M.5 part a, the cell diagram in the solution manual is:
Hg(l) | Hg2^2+(aq) || NO^3-(aq), H^+(aq) | NO(s) | Pt(s)
Hg(l) | Hg2^2+(aq) || NO^3-(aq), H^+(aq) | NO(s) | Pt(s)
- Tue Feb 25, 2020 11:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.7
- Replies: 1
- Views: 93
6L.7
How do you do this problem with the equilibriums?
- Tue Feb 25, 2020 11:06 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 1
- Views: 106
Platinum
In what case do you add platinum and when do you not when drawing cell diagrams?
- Mon Feb 24, 2020 3:44 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic/Voltaic Cells
- Replies: 4
- Views: 265
Re: Galvanic/Voltaic Cells
A galvanic cell requires no input of energy because the reactions are spontaneous and favorable. Electrons and cations travel from the anode to the cathode producing energy. A galvanic cell, overall, turns chemical energy into electrical energy.
- Mon Feb 24, 2020 3:38 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 9
- Views: 551
Re: Cell Diagrams
The | separates phases (Solid, aqueous, gas) and the || means a salt bridge and can also separate the anode and cathode.
- Mon Feb 24, 2020 3:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Flow of Galvanic cell
- Replies: 3
- Views: 196
Re: Flow of Galvanic cell
The cations move through the salt bridge or the porous disk because of the reasons ^^^. They are attracted to the negative cathode.
- Mon Feb 24, 2020 12:02 am
- Forum: Balancing Redox Reactions
- Topic: Acids and Bases
- Replies: 4
- Views: 353
Re: Acids and Bases
You add the H2O to balance out the oxygens and then add H+ to balance out the hydrogens and then the same amount of OH- as H+ you added. Then you combine them to form water.
- Sun Feb 23, 2020 11:30 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2
- Replies: 9
- Views: 485
Re: Test 2
The test will be in week 9 during discussion.
- Sun Feb 23, 2020 11:28 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic and Basic
- Replies: 3
- Views: 213
Re: Acidic and Basic
I would also like to know how to differentiate between acidic and basic reactions.
- Tue Feb 11, 2020 2:25 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 4D.3
- Replies: 1
- Views: 149
4D.3
The reaction of 1.40 g of carbon monoxide with excess water vapor to produce carbon dioxide and hydrogen gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113 8C to 22.799 8C. The calorimeter assembly is known to have a total heat capacity (calorimeter co...
- Tue Feb 11, 2020 2:10 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4C.15
- Replies: 1
- Views: 121
4C.15
Can someone explain how to differentiate between which heating curve is correct?
- Tue Feb 11, 2020 1:59 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4.C.13
- Replies: 1
- Views: 110
4.C.13
How do you break this problem down to solve for the ice melting and the water heating. The solution manual is not making sense? An ice cube of mass 50.0 g at 0.0 8C is added to a glass containing 400.0 g of water at 45.0 8C. What is the final tempera- ture of the system (see Tables 4A.2 and 4C.1)? A...
- Tue Feb 11, 2020 1:49 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 4C.3
- Replies: 1
- Views: 83
4C.3
Is the correct answer the one in the back of the book? I keep getting 342.8K for my final temperature. Calculate the final temperature and the change in enthalpy when 765 J of energy is transferred as heat to 0.820 mol Kr(g) at 298 K and 1.00 atm (a) at constant pressure; (b) at constant vol- ume. T...
- Tue Feb 11, 2020 1:47 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4C.7
- Replies: 3
- Views: 300
4C.7
How do you do this problem? I was using q = nH and q = mH but I am not getting the correct answer. "(a)Atitsboilingpoint,thevaporizationof0.579molCH4(l) requires 4.76 kJ of heat. What is the enthalpy of vaporization of methane? (b) An electric heater was immersed in a flask of boiling ethanol, ...
- Wed Jan 29, 2020 10:29 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4A.3
- Replies: 3
- Views: 142
4A.3
Can someone please explain this problem. The solution manual is using 101.325J as a conversion but I'm not sure where they are getting it from. Other than that, I still don't understand the problem.
- Sat Jan 25, 2020 12:45 pm
- Forum: Ideal Gases
- Topic: Topics on Test 1
- Replies: 37
- Views: 1192
Re: Topics on Test 1
Outline 1 and 2 except for 6E.
- Sat Jan 25, 2020 12:31 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: kA and kB
- Replies: 3
- Views: 209
Re: kA and kB
Yes that's right! Also remember that it's not like pH where the higher the number the stronger the base and the lower the number the stronger the acid. For both acids and bases, the lower the pKa or pKb the stronger the acid or base.
- Sat Jan 25, 2020 12:29 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka*Kb=Kw
- Replies: 5
- Views: 391
Re: Ka*Kb=Kw
Make sure you are using -14 not -4!
- Sat Jan 25, 2020 12:07 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Value of X
- Replies: 7
- Views: 184
Re: Value of X
Set up a K expression using an ICE table and solve for x setting the expression equal to Ka, Kb, or Kc.
- Sat Jan 25, 2020 12:04 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: biological examples
- Replies: 7
- Views: 266
biological examples
The following is stated on Outline 1 as things we have to know...
"Biological examples. For example: ATP hydrolysis; osmotic pressure"
Can anyone tell me what we have to know about it because I don't recall going over this?
"Biological examples. For example: ATP hydrolysis; osmotic pressure"
Can anyone tell me what we have to know about it because I don't recall going over this?
- Sat Jan 25, 2020 12:01 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure
- Replies: 3
- Views: 130
Pressure
In high school chem I learned that the way the reaction shifts based on an increase or decrease of pressure depends on the amount of moles on each side of the reaction. I know Prof. Lavelle said there was another way that was better to determine which way the reaction shifts, but I don't remember it...
- Sat Jan 25, 2020 11:55 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Partial Pressure vs. Concentration
- Replies: 5
- Views: 138
Partial Pressure vs. Concentration
It says on outline 1 that we have to know when to differentiate between using partial pressure and concentration for the equilibrium constant. How do we know which one to use when there are only gases but they don't give any other information like concentration or partial pressure?
- Sat Jan 25, 2020 11:47 am
- Forum: Ideal Gases
- Topic: R Constant
- Replies: 26
- Views: 1054
Re: R Constant
Here are the different gas constants. It depends on the units you are using in the equation. For PV=nRT you would usually use the 0.082.
- Wed Jan 22, 2020 10:21 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: 5I 25
- Replies: 2
- Views: 118
5I 25
Will we have to know how to factor a complicated problem like this one where there is a quadratic over a quadratic for tests?
- Sat Jan 11, 2020 1:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: liquids and aqueous solutions
- Replies: 4
- Views: 103
Re: liquids and aqueous solutions
Aqueous solutions have measurable and changeable concentrations. Liquids don't have significantly changeable concentrations and solids don't have measurable concentrations.
- Sat Jan 11, 2020 1:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Change in k
- Replies: 11
- Views: 469
Re: Change in k
This is true because of LeChatelier's principle that a reaction will try to minimize change to equilibrium. If more reactants are added the reaction shifts towards the products producing more product in the same ration that K was initially.
- Sat Jan 11, 2020 1:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Table Calculations
- Replies: 4
- Views: 90
Re: ICE Table Calculations
Basically, because we don't have access to a graphing calculator, anything that you can't do without it like a cubic function for example can be simplified.
- Sat Jan 11, 2020 1:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Assuming +/- x is Negligible
- Replies: 4
- Views: 162
Re: Assuming +/- x is Negligible
I'm pretty sure you are correct that if K < 10-5 you can use approximation.
- Thu Jan 09, 2020 11:46 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G3
- Replies: 8
- Views: 291
Re: 5G3
I believe only gases are included when finding equilibrium constants. Also, can someone explain how to ask a question on Chem Community? I cannot figure out how to. Thanks You have to go to a certain topic and then click on new topic in the top left corner. Name the subject something that people ca...
- Thu Jan 09, 2020 11:13 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G.9
- Replies: 4
- Views: 135
5G.9
Can someone explain how to understand this question? "A sample of ozone, O3, amounting to 0.10 mol, is placed in a sealed container of volume 1.0 L and the reaction 2 O3(g) S 3 O2(g) is allowed to reach equilibrium. Then 0.50 mol O3 is placed in a second container of volume 1.0 L at the same te...
- Sun Dec 01, 2019 1:14 pm
- Forum: Hybridization
- Topic: drawing out hybridization diagrams
- Replies: 1
- Views: 133
Re: drawing out hybridization diagrams
It's a possibility because we went over it in the notes, but I also don't think it would need to be detailed because it never showed up on the HW and the exams usually follow the format of the HW.
- Sun Dec 01, 2019 12:50 pm
- Forum: Hybridization
- Topic: Focus 2.45
- Replies: 3
- Views: 229
Re: Focus 2.45
Also why are there two hybridizations written for each bond even though they are the exact same thing? And why is the pi bond hybridization different from the sigma bond hybridization?
- Sat Nov 30, 2019 2:18 pm
- Forum: Hybridization
- Topic: Atomic Orbital Promotion
- Replies: 1
- Views: 149
Atomic Orbital Promotion
Can someone please explain the transition between a normal atomic orbital and the hybrid orbital? I mean when we write the electron configuration with the arrows and how it changes in hybrids.
Can someone also explain it in terms of ethene because the notes I took are not making sense to me?
Can someone also explain it in terms of ethene because the notes I took are not making sense to me?
- Sat Nov 30, 2019 2:11 pm
- Forum: Hybridization
- Topic: Counting Charge Clouds
- Replies: 2
- Views: 307
Counting Charge Clouds
When counting charge clouds does it matter whether it's a single, double, or triple bond or does it always count as 1 charge cloud?
- Sat Nov 30, 2019 2:10 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 7
- Views: 303
Hybridization
Just a clarification because I thought hybridization would be more complicated. Do we just have to draw the Lewis structure, count the amount of charge clouds, and memorize the hybrid orbitals for each amount of charge cloud and write it down?
Does it get more complicated than this for this course?
Does it get more complicated than this for this course?
- Sun Nov 24, 2019 9:03 pm
- Forum: Sigma & Pi Bonds
- Topic: sigma and pi bonds
- Replies: 27
- Views: 1553
Re: sigma and pi bonds
A single bond is a sigma bond and every other bond after that is a pi bond. For example, in a double bond, there's one sigma and one pi bond and in a triple bond there's one sigma and two pi bonds.
- Thu Nov 21, 2019 9:38 am
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bond Sites
- Replies: 5
- Views: 370
Hydrogen Bond Sites
What is considered a hydrogen bond site on a molecule?
- Wed Nov 20, 2019 5:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs. Nonpolar
- Replies: 6
- Views: 278
Polar vs. Nonpolar
I understand that CH2Cl2 is polar because a tetrahedral shape isn't completely symmetrical. However if a shape is symmetrical like a square planar would it be considered nonpolar? For example if it was a square planar with two Cl and two H atoms around a central atom, would it be considered non polar?
- Wed Nov 20, 2019 5:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.25
- Replies: 3
- Views: 194
Re: 2E.25
Could you say that it would only be nonpolar if all the atoms around the central atom were the same?
- Wed Nov 20, 2019 4:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.21
- Replies: 1
- Views: 76
2E.21
How do you do part a from 2E.21? It asks to draw the Lewis structure and give approximate bond angles of C2H4. Maybe I'm drawing it wrong but what is the central atom? I have the carbons bonded with two hydrogens bonded to each.
- Sat Nov 16, 2019 3:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs. Nonpolar
- Replies: 12
- Views: 718
Re: Polar vs. Nonpolar
It's better to determine whether a molecule is polar or non polar based on VSPER rather than Lewis Structure because it isn't always clear with the Lewis Structure. For H2O for example it seems like it would be non polar because it's symmetrical but the VSPER structure shows it's polar because of th...
- Sat Nov 16, 2019 2:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Trigonal Pyramid vs Trigonal Planar
- Replies: 6
- Views: 429
Re: Trigonal Pyramid vs Trigonal Planar
They are two completely different shapes. Trigonal planar has no lone pairs and 3 bonded pairs while trigonal pyramidal has 1 lone pair and 3 bonded pairs.
- Sat Nov 16, 2019 2:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing Molecular Structures
- Replies: 8
- Views: 485
Re: Drawing Molecular Structures
Will we need to know how to draw the molecular structures in this way for the test?
- Sat Nov 16, 2019 2:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Inter-molecular Electron Repulsion
- Replies: 6
- Views: 233
Re: Inter-molecular Electron Repulsion
What is an example of a lone-bonding pair?
- Sat Nov 16, 2019 2:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Symmetry and Polarity
- Replies: 13
- Views: 904
Re: Symmetry and Polarity
Are the molecules that are considered polar the ones with no lone electron pairs? So only linear, tetrahedral, trigonal planar, etc.?
- Sat Nov 16, 2019 2:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSPER Formula for Compounds with No Lone Pairs
- Replies: 4
- Views: 256
VSPER Formula for Compounds with No Lone Pairs
What would the VSPER formula for a compound with a tetrahedral shape look like?
Do we just not include "E" when writing the formula?
Do we just not include "E" when writing the formula?
- Sat Nov 16, 2019 2:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSPER Formula
- Replies: 2
- Views: 99
VSPER Formula
Do we have to know how to identify molecular shapes based on just a VSPER formula or will he most likely give us a compound that we have to find the Lewis Structure of to determine the VSPER shape?
- Sat Nov 16, 2019 2:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 9
- Views: 487
Re: Bond Angles
It's probably easiest to just memorize a chart with all the bond angles stated, but for the test he said we just have to be able to say that a trigonal pyramidal shape has a smaller bond angle than a tetrahedral because of the lone pair having more repulsion than the bonded pair.
- Wed Nov 13, 2019 7:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.5 b
- Replies: 4
- Views: 100
2E.5 b
OClO has 19 valence electrons so it's a radical. Do we count the extra electron even though it's not in a pair when determining shape?
- Tue Nov 05, 2019 11:28 pm
- Forum: Octet Exceptions
- Topic: When to use Expanded Octet?
- Replies: 2
- Views: 196
When to use Expanded Octet?
Are you supposed to use an expanded octet if you can make a Lewis Structure without it? For example, in ClO would I give Cl 9 electrons by making a double bond or leave it with 7 with a single bond even though the single bond gives Cl a -1 formal charge?
- Sun Nov 03, 2019 5:18 pm
- Forum: Lewis Structures
- Topic: line structure
- Replies: 1
- Views: 127
Re: line structure
Line structures omit lone electron pairs and just show bonds while Lewis structures have both.
- Sun Nov 03, 2019 5:17 pm
- Forum: Lewis Structures
- Topic: More stable structures
- Replies: 2
- Views: 175
Re: More stable structures
I'm pretty sure the stability of a Lewis structure is based off of formal charge and which atoms have what formal charges. Typically, the more electronegative atoms rather have a negative formal charge than less electronegative atoms.
- Sun Nov 03, 2019 2:59 pm
- Forum: Octet Exceptions
- Topic: Identifying Radicals
- Replies: 6
- Views: 378
Re: Identifying Radicals
Can someone explain this by using a Lewis structure too?
Ashley, I think they are important because they are highly reactive and exist for a short time.
Ashley, I think they are important because they are highly reactive and exist for a short time.
- Sat Nov 02, 2019 9:51 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2B.9
- Replies: 1
- Views: 183
2B.9
How do you know what is ionic and what isn't?
For part b and c it's obvious because there's a metal involved, but for ammonium chloride, they are all nonmetals.
For part b and c it's obvious because there's a metal involved, but for ammonium chloride, they are all nonmetals.
- Sat Nov 02, 2019 6:35 pm
- Forum: Lewis Structures
- Topic: Formal Charge for Lewis Structures
- Replies: 4
- Views: 249
Formal Charge for Lewis Structures
So I went to the UA review session on Friday and they discussed using formal charge to determine the best way to draw a Lewis Structure. I've been trying to use that but it isn't working and I keep getting the wrong answer for the homework. Is there a certain time when we should or shouldn't use the...
- Sun Oct 27, 2019 12:16 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2.A.17
- Replies: 3
- Views: 144
2.A.17
I'm confused as to how to find how many valence electrons are present for these ions. I usually just count back on the periodic table because they're all cations and then determine the amount of valence electrons for the element I land on, but I keep getting them wrong. Is there another way to do th...
- Sun Oct 27, 2019 12:02 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons 2A.1
- Replies: 2
- Views: 85
Valence Electrons 2A.1
"Give the number of valence electrons (including d electrons) for each of the following elements: (a) Sb; (b) Si; (c) Mn; (d) B." For part c, do you count the d electrons because the subshell is not full because for the rest you also count subshells that are full if the shell isn't full? H...
- Sun Oct 27, 2019 11:31 am
- Forum: Properties of Light
- Topic: 1.31
- Replies: 4
- Views: 201
1.31
How do you find the kinetic energy of the electrons emitted? "In a recent suspense film, two secret agents must penetrate a criminal's stronghold monitored by a lithium photomultiplier cell that is continually bathed in light from a laser. If the beam of light is broken, an alarm sounds. The ag...
- Sun Oct 27, 2019 11:21 am
- Forum: Trends in The Periodic Table
- Topic: HW: 1.13
- Replies: 2
- Views: 120
Re: HW: 1.13
Does anyone know if we could answer this question by saying that nitrogen has one electron in each orbital which has a higher stability and that fluorine has a high electron affinity because it wants an octet and doesn't want to lose an electron instead?
Do we have to mention electron repulsion?
Do we have to mention electron repulsion?
- Sun Oct 27, 2019 11:16 am
- Forum: Properties of Light
- Topic: Homework 1.3
- Replies: 2
- Views: 102
Re: Homework 1.3
I used E=hc(wavelength) too but I got 753668J for my final answer. I'm confused on what we're both doing wrong. Can someone help?
- Sun Oct 20, 2019 11:10 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Homework 1E.7
- Replies: 3
- Views: 112
Re: Homework 1E.7
What rule is part C of this question violating that makes it an excited state?
- Sun Oct 20, 2019 10:38 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1.E.5
- Replies: 1
- Views: 80
1.E.5
Can someone please explain this entire question...why each is true/false? I don't understand. "Which of the following statements are true for many-elec- tron atoms? If false, explain why. (a) The effective nuclear charge Zeffe is independent of the number of electrons present in an atom. (b) El...
- Wed Oct 16, 2019 2:35 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 1B.27 Hw Help
- Replies: 5
- Views: 150
Re: 1B.27 Hw Help
For ∆x, I got 6.6 x 10-36m also, but the answer in the back of the book and the solution manual is 1.3 x 10-36m. Which is the correct answer?
- Wed Oct 16, 2019 2:21 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 1.D.23 [ENDORSED]
- Replies: 2
- Views: 106
1.D.23 [ENDORSED]
"How many orbitals can have the following quantum numbers in an atom:(a)n=2, l=1; (b)n=4, l=2, ml=22; (c)n=2; (d)n=3, l=2, ml=1?" For a, is the number of orbitals only dependent on the subshell (p) and the amount of orientations possible for it? For b and d, is it only 1 because the orient...
- Wed Oct 16, 2019 1:29 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: HW Question 1.D.13
- Replies: 3
- Views: 227
Re: HW Question 1.D.13
I don't understand what to use given in the problem to get the answer. I thought b was 11 because if n=6 and l=5, then shouldn't ml = -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5? Also can someone explain c and d too?
- Sat Oct 12, 2019 6:26 pm
- Forum: DeBroglie Equation
- Topic: Mass of Protons, Neutrons, Electrons, Etc.
- Replies: 3
- Views: 73
Mass of Protons, Neutrons, Electrons, Etc.
2 questions:
For the mass of protons, neutrons, and electrons can we just look it up online or is there a certain value the book wants us to use and where would I find these values?
For tests, will we be given the mass of these particles?
For the mass of protons, neutrons, and electrons can we just look it up online or is there a certain value the book wants us to use and where would I find these values?
For tests, will we be given the mass of these particles?
- Sat Oct 12, 2019 6:18 pm
- Forum: Einstein Equation
- Topic: 1B.15
- Replies: 2
- Views: 129
1B.15
"The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 3 103 km?s21. (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 re...
- Sat Oct 12, 2019 6:04 pm
- Forum: Properties of Light
- Topic: HW 1.A #11
- Replies: 4
- Views: 141
Re: HW 1.A #11
I don't understand how the answer given answers the question. Can someone please explain? Why is grouping the series related to the base energy level?
- Sat Oct 12, 2019 10:34 am
- Forum: Properties of Light
- Topic: HW 1.A #9
- Replies: 3
- Views: 149
Re: HW 1.A #9
Here's an electromagnetic spectrum I found for reference. A wavelength of 340 nm would be suntanning because the sun emits UV rays. A wavelength of 1m or 1x10^9 nm would be microwaving popcorn because that wavelength falls under microwave radar. A wavelength of 2.5 nm would be x-ray because of the s...
- Sat Oct 12, 2019 10:13 am
- Forum: *Particle in a Box
- Topic: Particle in a box
- Replies: 2
- Views: 721
Re: Particle in a box
Particles have discreet energies with only certain stable wavelengths allowed in a circular standing wave around the nucleus. Professor Lavelle was specifically talking about electrons as being the particle in a box. An electron bound to an atom is like a particle in a box in that it has to stay amo...
- Thu Oct 03, 2019 6:19 pm
- Forum: SI Units, Unit Conversions
- Topic: Advice
- Replies: 3
- Views: 200
Re: Advice
This can be helpful for converting between the prefixes to get to the base units on the metric system.
- Thu Oct 03, 2019 6:10 pm
- Forum: Limiting Reactant Calculations
- Topic: M.11
- Replies: 3
- Views: 271
M.11
"A reaction vessel contains 5.77 g of white phosphorus and 5.77 g of oxygen. The first reaction to take place is the formation of phosphorus(III) oxide, P 4 O 6 : P 4 (s) + 3 O 2 (g) > P 4 O 6 (s). If enough oxygen is present, the oxygen can react further with this oxide to produce phosphorus(V...
- Thu Oct 03, 2019 3:53 pm
- Forum: Empirical & Molecular Formulas
- Topic: Tips for Finding Which Number to Multiply a Decimal By to Get a Whole Number
- Replies: 10
- Views: 1084
Tips for Finding Which Number to Multiply a Decimal By to Get a Whole Number
When doing empirical formula problems, after you divide by the smallest number of moles, sometimes you get a decimal which you have to convert into a whole number for the formula. I know how what to multiply by when they're simple decimals like 0.5, 0.33, 0.66, 0.25, but how do I know what number to...
- Thu Oct 03, 2019 3:44 pm
- Forum: Balancing Chemical Reactions
- Topic: Confusion on H.3
- Replies: 2
- Views: 140
Confusion on H.3
For Question 3, Section H, I balanced the equation and got:
SiH4 + 2H2O > SiO2 + 4H2
but the answer doubles all the coefficients, even though the way I did it above is balanced. Is there a reason for this?
Thank you in advance!
SiH4 + 2H2O > SiO2 + 4H2
but the answer doubles all the coefficients, even though the way I did it above is balanced. Is there a reason for this?
Thank you in advance!