Search found 59 matches
- Thu Dec 05, 2019 12:53 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: How to tell if a salt is neutral, acidic, or basic?
- Replies: 1
- Views: 159
How to tell if a salt is neutral, acidic, or basic?
Do we just need to know the reactants that form the salt and see if those reactants can form strong acids/bases?
- Thu Dec 05, 2019 12:47 pm
- Forum: Bronsted Acids & Bases
- Topic: HCl, HBr, HI, etc.
- Replies: 2
- Views: 235
Re: HCl, HBr, HI, etc.
YEs since fluorine is the most electronegative, it has the highest electron withdrawing ability making the molecule more stable and less able to dissociate its H+ ions in water.
- Thu Dec 05, 2019 12:45 pm
- Forum: Bronsted Acids & Bases
- Topic: strong bases
- Replies: 1
- Views: 179
Re: strong bases
Typically bases with hydroxides are considered strong bases, the book also has exampels that could be exceptions.
- Thu Dec 05, 2019 12:44 pm
- Forum: Naming
- Topic: Iron compounds
- Replies: 1
- Views: 197
Re: Iron compounds
If the compound is an anion, you would use ferrate but if it is neutral you would just write iron.
- Thu Dec 05, 2019 1:36 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: different Rydberg
- Replies: 3
- Views: 371
Re: different Rydberg
E/-h can be rearranged (based on the E=hv and c=lambda * v equations) to represent the left side and the coefficients of the right side of the equation. N2 is used when you are trying to determine the change in energy when an electron switches from different energy levels (n) which is when you would...
- Thu Dec 05, 2019 1:34 am
- Forum: Lewis Acids & Bases
- Topic: HW #6.13
- Replies: 1
- Views: 210
Re: HW #6.13
First part is no since the entire molecule has the same number and types of bonds/lone pairs of electrons. Second part is lewis acid since B(OH)3 gives a proton of one of its Os to H2O to form H3O+. Since B(OH)3's conjugate base is [B(OH)4]-, we know that boric acid must lose an H in a solution so i...
- Thu Dec 05, 2019 1:22 am
- Forum: Lewis Acids & Bases
- Topic: Salts as Acids and Bases
- Replies: 2
- Views: 236
Re: Salts as Acids and Bases
Cl- is a neutral ion and thus does not affect pH of a solution. If you are able to write the acid disassociation equation with the ion on both sides, you know that the atom is neutral.
- Tue Dec 03, 2019 12:40 pm
- Forum: Polyprotic Acids & Bases
- Topic: Why is HClO4 stronger than H3PO4?
- Replies: 3
- Views: 1266
Why is HClO4 stronger than H3PO4?
Since H3PO4 is polyprotic, shouldn't it be a stronger acid than HClO4 despite Cl's electronegativity?
- Sun Dec 01, 2019 7:49 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Salt
- Replies: 5
- Views: 375
Re: Salt
It depends what molecules the salt breaks up into, depending on what other reactants are present in the chemical equation. For example, dissolving the salt of strong base and strong acid makes a neutral solution, salt of strong base and weak acid makes a basic solution, and lastly, a salt of weak ba...
- Sun Dec 01, 2019 7:44 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: PH
- Replies: 5
- Views: 416
Re: PH
To calculate pH, you take the negative log of the concentration of hydronium.
- Sun Dec 01, 2019 7:43 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Ligand
- Replies: 4
- Views: 351
Re: Ligand
WHat is the best way to determine if a ligand is a chelating one?
- Sun Dec 01, 2019 7:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Past exams
- Replies: 7
- Views: 710
Re: Past exams
There are test banks, I believe there is one at the student activities center (but you have to submit a test first), that have previous tests. I know some clubs/orgs on campus have their own ones as well.
- Sun Dec 01, 2019 7:39 pm
- Forum: Naming
- Topic: Naming Order
- Replies: 5
- Views: 368
Re: Naming Order
If there is a neutral molecule too, do you write its name before the hydrate?
- Sun Dec 01, 2019 7:37 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Do you have to draw lewis structures when determining if a ligand is polydentate?
- Replies: 1
- Views: 147
Do you have to draw lewis structures when determining if a ligand is polydentate?
Is that the best way to determine how many bonding areas there are for a ligand?
- Sun Nov 24, 2019 1:20 pm
- Forum: Naming
- Topic: Heme Complex
- Replies: 3
- Views: 249
Re: Heme Complex
Based on what he said in class, a heme complex forms when an iron ion binds to the porphyrin ligand. When this complex binds with another protein (the example he used was histidine), they make up myoglobin (responsible for transporting O2 in muscles cells.
- Sun Nov 24, 2019 1:08 pm
- Forum: Hybridization
- Topic: Strength of sigma and pi bonds
- Replies: 8
- Views: 700
Re: Strength of sigma and pi bonds
Since pi bonds represent parts of double and triple bonds (which are considered stronger than single bonds), why aren't pi bonds stronger?
- Sun Nov 24, 2019 1:05 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Charges
- Replies: 4
- Views: 283
Re: Charges
Memorization might be needed for the charges of certain transition metals depending on the ionic compound they create with another element. For example, platinum ion has the possibility of having 2+ or 4+ charge.
- Wed Nov 20, 2019 8:04 pm
- Forum: Dipole Moments
- Topic: Hydrogen Bonding
- Replies: 20
- Views: 1172
Re: Hydrogen Bonding
yes, you still should figure out the dipole moments of all the atoms to determine the overall net dipole moment of the molecule
- Wed Nov 20, 2019 7:59 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: IMF strength
- Replies: 4
- Views: 278
Re: IMF strength
hydrogen bonds are the strongest
- Sun Nov 17, 2019 10:59 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent
- Replies: 3
- Views: 249
Re: Bent
Yes, 2 bonding atoms and 1 lone pair is also a bent shape. Since there are two lone pairs in the first example, this molecule's atoms experience more repulsion and are pushed closer together which decreases the bond angle in comparison to a bent molecule with only one lone pair.
- Sat Nov 16, 2019 9:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E 11 b)
- Replies: 4
- Views: 214
Re: 2E 11 b)
When you complete the octets of the chlorine atoms, you have 24/28 electrons filled for the molecule. Adding double or triple bonds would decrease this number of overall electrons used by taking one from each atom. The only way to fill the quota of 28 electrons is to add two lone pairs, which is pos...
- Sat Nov 16, 2019 9:47 pm
- Forum: Bond Lengths & Energies
- Topic: Lone pairs
- Replies: 7
- Views: 648
Re: Lone pairs
How do you determine whether electrons are axial or equatorial?
- Sat Nov 16, 2019 9:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Electronegativity
- Replies: 5
- Views: 311
Re: Electronegativity
You don't need to know the exact values but the general trends (F being the most) and the fact that noble gases have none.
- Sat Nov 16, 2019 8:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 4
- Views: 274
Re: Bond Angles
Not sure if this is what you're exactly referring to but the number of lone pairs, which force bonded electron pairs closer to one another, decreases the bond angle
- Sat Nov 16, 2019 7:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 5
- Views: 380
Re: Bond Angles
If there are more lone pairs present, the repulsion that they cause forces the bonding atoms away causing there to be a decrease in bond angle size. Lavelle said you do not need to know the exact numbers but the idea that more lone pair electrons force bonding electrons closer together, decreasing a...
- Sat Nov 16, 2019 6:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 6
- Views: 620
Re: Lone Pairs
lone pairs count towards molecular geometry not electron domain geometry. so in the case of 4 electron domains (3 bonding and one lone pair), the electron domain geometry would be tetrahedral while the molecular geometry would be trigonal pyramidal.
- Sat Nov 16, 2019 6:55 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 10
- Views: 655
Re: Electronegativity
Elements that have a high need to complete their valence shell through adding electrons have higher electronegativity values (since that is its ability to attract an electron to itself). Fluorine has the highest since it needs one more electron to complete its valence shell and experiences less elec...
- Sat Nov 16, 2019 6:49 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: strongest intermolecular forces
- Replies: 7
- Views: 775
Re: strongest intermolecular forces
in order of strongest to weakest forces:
ion-ion, h, ion-dipole, dipole-dipole=london dispersion (depending on molecule size)
ion-ion, h, ion-dipole, dipole-dipole=london dispersion (depending on molecule size)
- Sat Nov 16, 2019 6:28 pm
- Forum: Lewis Structures
- Topic: Bond amount
- Replies: 2
- Views: 133
Re: Bond amount
You want to fill the octets of outside atoms first, then try and complete the octet of the central atom. If you are missing electrons, usually a double or even triple bond will help. The central atom should usually have a complete octet though there are exceptions like Dr. Lavelle discussed in class.
- Fri Nov 08, 2019 10:26 am
- Forum: Octet Exceptions
- Topic: General principles of octet exception
- Replies: 7
- Views: 344
Re: General principles of octet exception
Here is what I wrote down in my notes:
Less than 8 e-: H, B, He, Be (Aluminum and Boron only need 6 valence electrons)
More than 8 e-: P, S, Cl, Xe and below
Less than 8 e-: H, B, He, Be (Aluminum and Boron only need 6 valence electrons)
More than 8 e-: P, S, Cl, Xe and below
- Fri Nov 08, 2019 10:19 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: central atom
- Replies: 21
- Views: 1048
Re: central atom
APatel_4A wrote:How do we know what the central atom should be?
The central atom is usually the least electronegative one.
- Wed Nov 06, 2019 2:10 pm
- Forum: Ionic & Covalent Bonds
- Topic: Why is the ionization energy of nitrogen higher than that of oxygen's?
- Replies: 11
- Views: 1011
Re: Why is the ionization energy of nitrogen higher than that of oxygen's?
To add to this, Boron (and elements under) have higher ionization energies than Beryllium (and elements under) for a similar reason of electron shielding.
- Wed Nov 06, 2019 2:07 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity Formula / Calculation
- Replies: 5
- Views: 2974
Re: Molarity Formula / Calculation
Molarity is equal to moles of solute per one liter of solution. So if there is a question that tells you there is a certain amount of a compound dissolved into water, you would find the molarity of that solution by using the formula (you might have to convert grams to moles or milliliters to liters)...
- Tue Nov 05, 2019 4:19 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: lyman and balmer
- Replies: 3
- Views: 231
Re: lyman and balmer
It is also important to know that the balmer series deals with visible light while lyman deals with UV.
- Sun Oct 27, 2019 10:51 pm
- Forum: Resonance Structures
- Topic: Midterm
- Replies: 4
- Views: 152
Re: Midterm
Do you know if this also includes the material from the first test since it was high school stuff?
- Sun Oct 27, 2019 10:42 pm
- Forum: Resonance Structures
- Topic: Arrangement of Atoms
- Replies: 3
- Views: 96
Re: Arrangement of Atoms
Lewis structures with formal charges of each atom that are closest to 0 represent the lowest energy arrangement of the atoms and electrons within a molecule. So, the lowest formal charges of a molecule are typically more representative of the true nature of that molecule.
- Sun Oct 27, 2019 10:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2A. 13 Question
- Replies: 5
- Views: 182
Re: 2A. 13 Question
Writing the electron configuration first is a good way to go because you need to determine what sublevel each atom has valence electrons in. When you form a positive ion, you take away electrons from the valence level first.
- Sun Oct 27, 2019 10:36 pm
- Forum: Octet Exceptions
- Topic: Radicals
- Replies: 9
- Views: 355
Re: Radicals
These are atoms that have at least one unpaired electron which can be identified by drawing their lewis structure or writing their electron configuration.
- Sun Oct 27, 2019 10:33 pm
- Forum: Electronegativity
- Topic: Finding Electronegativity
- Replies: 2
- Views: 137
Re: Finding Electronegativity
Electronegativity increases from left to right on a periodic table while decreasing down a group, so the order would be:
selenium, antimony, tin, indium
selenium, antimony, tin, indium
- Sun Oct 20, 2019 6:54 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E.17 Ion formation
- Replies: 1
- Views: 66
1E.17 Ion formation
For 1E.17, it asks what type of orbital an electron will be removed from (1s, 2p, 3d, 4f, etc.) for various atoms. What are the rules for which orbitals are removed before others?
- Sun Oct 20, 2019 6:49 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing Electron Configurations Help
- Replies: 3
- Views: 175
Writing Electron Configurations Help
In class, Dr. Lavelle said to write configurations in order of increasing energy. However, in the book it gives examples/answers in a different way where the configuration is written in the order of increasing coefficients for each sublevel (Ex for bismuth: [Xe] 4f^14, 5d^10, 6s^2, 6p^3). Does the b...
- Sun Oct 20, 2019 6:40 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Homework Problem A.15
- Replies: 2
- Views: 163
Re: Homework Problem A.15
Since we are dealing with the lyman series (uv light), n1 is equal to 1. Rearranging the rydberg equation from the book, you can plug in the known values (for speed of light, lambda/wavelength, rydberg's constant, and n1) and solve for n2 (the final energy level): v=c/lambda=r(1/(n1)^2 - 1/(n2)^2) w...
- Sun Oct 20, 2019 6:24 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: s-, p-, d- ,f- orbitals
- Replies: 10
- Views: 493
Re: s-, p-, d- ,f- orbitals
In the p shell, there are 3 orbitals in which electrons can exist: px, py, and pz. The subscript tells you how the orbital is oriented where px is located along the x-axis. The 2 in front says that the electron exists in the second level of the p subshell and in the first orbital.
- Sun Oct 20, 2019 6:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Atomic spectra module
- Replies: 1
- Views: 159
Re: Atomic spectra module
Energy of one photon = hv
1. Use the equation c=lambda * v to get the frequency
2. Use the frequency to find the energy of one photon using (E=hv)
3. Then use the energy given (11 J) and divide it by the energy of one photon to determine the number of photons generated
1. Use the equation c=lambda * v to get the frequency
2. Use the frequency to find the energy of one photon using (E=hv)
3. Then use the energy given (11 J) and divide it by the energy of one photon to determine the number of photons generated
- Sun Oct 13, 2019 1:56 pm
- Forum: Properties of Light
- Topic: wavelike properties
- Replies: 4
- Views: 260
Re: wavelike properties
Diffraction is the main one that he discussed in class. Constructive interference, where waves with same peaks interact with one another and gain amplitude, and destructive interference, where peaks interact with troughs and diminish in amplitude, both also can be used to describe diffraction patter...
- Sun Oct 13, 2019 1:33 pm
- Forum: General Science Questions
- Topic: Units question for 1B.5
- Replies: 2
- Views: 146
Units question for 1B.5
What units does keV refer to? Since it is for energy, how would you convert this to joules or do you use these units instead for calculations?
- Sun Oct 13, 2019 1:29 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra for H
- Replies: 5
- Views: 217
Re: Atomic Spectra for H
The equation is: En = -hR/n^2 where n is the energy level of the electron and r is rydberg's constant (3.29*10^15 Hz) The different series (balmer,lyman, etc) are used to describe the lines of emissions of the electrons of the Hydrogen atom but we have not discussed whether they can be used for othe...
- Sun Oct 13, 2019 1:23 pm
- Forum: Photoelectric Effect
- Topic: #1B.3
- Replies: 1
- Views: 107
#1B.3
I know that the correct answer is D, but is it because of the way the electromagnetic radiation acts when it leads to the emission of electrons for the photoelectric effect or is there another reason that supports the idea that light has particle-like properties?
- Sun Oct 13, 2019 1:13 pm
- Forum: Photoelectric Effect
- Topic: Problem 1.15
- Replies: 1
- Views: 81
Re: Problem 1.15
Yes, the electron moves from energy levels 1 to 3 as it emits the specific energy.
- Fri Oct 11, 2019 12:19 am
- Forum: Photoelectric Effect
- Topic: Question about the application of the effect
- Replies: 2
- Views: 219
Question about the application of the effect
Are there any real-world/naturally occurring examples of the photoelectric effect? I don't see how this effect manifests itself besides in a laboratory setting.
- Fri Oct 11, 2019 12:17 am
- Forum: Molarity, Solutions, Dilutions
- Topic: G5
- Replies: 2
- Views: 402
Re: G5
molarity=mol/volume of solution
So, you first can calculate the molarity of the sodium carbonate solution. With this, you can use the mole to mole ratio of the various compounds in each part and the molarity equation to calculate the desired amounts needed for the volumes.
So, you first can calculate the molarity of the sodium carbonate solution. With this, you can use the mole to mole ratio of the various compounds in each part and the molarity equation to calculate the desired amounts needed for the volumes.
- Fri Oct 11, 2019 12:11 am
- Forum: Properties of Light
- Topic: Relationship between lambda and nu
- Replies: 5
- Views: 1179
Re: Relationship between lambda and nu
Units wise, lamba (wavelength) is represented by meters while nu (frequency) is represented by Hz or 1/s. When you multiply the two, you get m/s which is why the product of the two gives you the speed of light, c.
- Fri Oct 11, 2019 12:08 am
- Forum: Einstein Equation
- Topic: E=hv [ENDORSED]
- Replies: 52
- Views: 18459
Re: E=hv [ENDORSED]
E=energy of photon
h=planck's constant (6.626 × 10-34 m^2*kg/s)
v=frequency in Hz
h=planck's constant (6.626 × 10-34 m^2*kg/s)
v=frequency in Hz
- Fri Oct 11, 2019 12:02 am
- Forum: Properties of Light
- Topic: HW 1.A #11
- Replies: 4
- Views: 177
Re: HW 1.A #11
It is definitely a confusing question and I think it asks what is common with all the electrons found within a certain series. One thing is that they all have the same base energy level.
- Wed Oct 02, 2019 11:44 pm
- Forum: Empirical & Molecular Formulas
- Topic: Chapter F Problem 15
- Replies: 4
- Views: 517
Chapter F Problem 15
Diazepam, a drug used to treat anxiety, has the mass percentage composition 67.49% C, 4.60% H, 12.45% Cl, 9.84% N, and 5.62% O. What is the empirical formula of the compound? I was wondering how we would calculate the molar mass of diazepam to solve for its empirical formula? Is this a common compou...
- Wed Oct 02, 2019 11:39 pm
- Forum: Limiting Reactant Calculations
- Topic: Cases in which actual product is greater than theoretical?
- Replies: 3
- Views: 179
Re: Cases in which actual product is greater than theoretical?
Measuring errors in which compounds are thought to weigh less than they actually do could contribute to a greater yield than calculated. Certain chemicals also "age" with time and can produce byproducts that increase mass that may not be considered in calculations. Generally, any informati...
- Wed Oct 02, 2019 11:29 pm
- Forum: Empirical & Molecular Formulas
- Topic: Fundamental F question 7
- Replies: 3
- Views: 240
Re: Fundamental F question 7
The question gives you the formula for the desired compound as M2O. This means that there are twice as many moles of oxygen as there are for M. So, we can determine the mass of O in the compound by first assuming the mass of the compound to be 100g. As a result, 100-88.8 = 11.2 grams of oxygen. We c...
- Wed Oct 02, 2019 11:19 pm
- Forum: Balancing Chemical Reactions
- Topic: Net # of moles produced
- Replies: 4
- Views: 521
Re: Net # of moles produced
On the reactants side, you have 4 moles of butane reacting with 26 moles of oxygen. This produces 16 moles of carbon dioxide and 20 moles of water. All compounds are gases so you have 30 total moles of gases on the left side of the equation and 36 moles of gases on the right. 36 - 30 = 6 moles of ga...
- Wed Oct 02, 2019 11:13 pm
- Forum: Balancing Chemical Reactions
- Topic: Figuring Out State Symbols
- Replies: 3
- Views: 428
Re: Figuring Out State Symbols
From my experience, common compounds (such as acids/bases, gases, and salts) and reactions (combustion) are usually easily identifiable based on their molecular formula. For example, acids/bases are aqueous in a solution with water while all reactants/products in a combustion reaction are gases. Als...