## Search found 52 matches

Sun Dec 08, 2019 5:28 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: negative pH
Replies: 4
Views: 97

### Re: negative pH

It means it’s a really strong acid.
Sat Dec 07, 2019 12:27 am
Forum: Empirical & Molecular Formulas
Topic: charge
Replies: 4
Views: 215

### Re: charge

The charge is 2- because you calculate the formal charge on each atom. For the single bonded oxygens, the formal charge is -1 because you take the valence electrons and subtract the lone pairs and half the bonding pairs, 6-(6 + .5(2)). The double bonded oxygens have a formal charge of 0, 6-(4 + .5(4...
Wed Dec 04, 2019 10:20 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.1
Replies: 3
Views: 133

### Re: 6B.1

I don't know if this is easier, but I made the molarity of the original solution equal to 100M and the second solution's molarity equal to 12% of the original, or 12 M. It'd allow you to have actual numbers for the H3O+ concentration at least. You could then find out the pH of each solution and subt...
Wed Dec 04, 2019 10:00 am
Forum: Lewis Acids & Bases
Topic: Strong Acids
Replies: 6
Views: 106

### Re: Strong Acids

Strong acids also tend to form anions that are stable after it is deprotonated.
Wed Dec 04, 2019 9:52 am
Forum: Naming
Topic: 9C 1 part a
Replies: 2
Views: 67

### Re: 9C 1 part a

They used cyano before they changed the naming system. Cyanido is the newer naming for cyanide as a ligand, but I think Dr. Lavelle accepts either of them.
Wed Dec 04, 2019 9:47 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.9 (i)
Replies: 1
Views: 52

### Re: 6B.9 (i)

I got the same answer as you, so I think it might be a mistake in the book.
Sun Dec 01, 2019 1:49 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6b.9
Replies: 3
Views: 80

### Re: 6b.9

-log [H3O+] = pH. They give you that the pH is .75, so -log [H3O+] = .75. You then isolate the [H3O+]. The same thing applies for the [OH-]. You know the pH of the solution is 0.75, so you'd subtract that value from 14, giving you pOH. -log [OH-] = pOH, so -log [OH-] = 13.25. Isolate the [OH-] and t...
Sun Dec 01, 2019 1:09 am
Forum: Amphoteric Compounds
Topic: 6A.17
Replies: 3
Views: 63

### Re: 6A.17

a) basic
b) acidic
c) amphoteric
d) amphoteric
Wed Nov 27, 2019 11:43 am
Forum: Naming
Topic: Alphabetical Order
Replies: 6
Views: 88

### Re: Alphabetical Order

Can anyone walk me through an example? If you're looking at 9c.1c, they give you [Co(CN)5 (OH2)] 2-. So if you'd start off by listing the ligands first: cyanide and water. If water is a ligand, you'd call it aqua and if cyanide is the ligand, you'd change it to cyanido because the ending of cyanide...
Wed Nov 27, 2019 11:26 am
Forum: Naming
Topic: Naming coordination compounds
Replies: 1
Views: 67

### Re: Naming coordination compounds

As an overview, your ligands usually come first followed by the metal atom and the oxidation state of the metal atom in Roman numerals. The ligands are supposed to be listed in alphabetical order, and greek prefixes are used to distinguish how many of each ligand is present. With the ligands, if the...
Wed Nov 27, 2019 11:05 am
Forum: Naming
Topic: Naming Coordination Compound with Iron
Replies: 4
Views: 99

### Re: Naming Coordination Compound with Iron

Iron is ferrate because the chemical symbol of the metal is derived from its Latin name, ferrum. I think all elements with a chemical symbol derived from a Latin stem use the beginning portion of the latin stem when naming the compound.
Sun Nov 24, 2019 12:49 am
Forum: Naming
Topic: [Co(NH3)5Cl]Cl H2O
Replies: 4
Views: 87

### Re: [Co(NH3)5Cl]Cl H2O

There's a table on page 724 that's super helpful for memorizing the more common ligands, so I'm assuming we'll probably have to know at least those ones for the test.
Sun Nov 24, 2019 12:13 am
Forum: Dipole Moments
Topic: Dipole Induced- Dipole Induced
Replies: 13
Views: 378

### Re: Dipole Induced- Dipole Induced

Induced dipole-induced dipole forces can occur in all molecules because all molecules have electron clouds that can be distorted by shifting electron clouds in another molecule.
Sat Nov 23, 2019 11:53 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: dipole-dipole in a solid phase vs gas phase
Replies: 15
Views: 309

### Re: dipole-dipole in a solid phase vs gas phase

With gases, they occupy more space so the attraction between the molecules are weak. Solids on the other hand are more restricted in their movement, so they have stronger dipole-dipole interactions than gases would.
Sat Nov 23, 2019 11:28 pm
Forum: Naming
Topic: Prefixes
Replies: 4
Views: 84

### Re: Prefixes

Greek prefixes indicate the number of ligands, so you use the other prefixes to prevent confusion. I think you use those prefixes when the ligand has a greek prefix already in the name or if the ligand is polydentate.
Sat Nov 23, 2019 11:16 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: ligand
Replies: 3
Views: 62

### Re: ligand

A ligand is an ion or molecule that's attached to a central metal atom and creates a coordination complex.
Sat Nov 16, 2019 1:21 am
Forum: General Science Questions
Topic: Test 2
Replies: 4
Views: 101

### Re: Test 2

I think in lecture today Dr. Lavelle said that we would also have to know pi and sigma bonds, but I think we're going over that on Monday.
Sat Nov 16, 2019 12:49 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F problem 3
Replies: 3
Views: 83

### Re: 3F problem 3

Dipole-dipole interactions exist between polar molecules because one end of the molecule is more negatively charged while the other end is more positively charged. With a, the molecule is nonpolar because the electronegativity difference between the C-H bond isn't large enough to constitute a perman...
Sat Nov 16, 2019 12:38 am
Forum: Limiting Reactant Calculations
Topic: A different way
Replies: 8
Views: 457

### Re: A different way

If given the grams of reactants, you can technically convert each reactant to moles and then convert one of the reactants to moles of the other reactant and use the coefficients in the chemical equation to determine the limiting reactant. So for instance, if you have 2H2 + O2 --> 2H2O and you find t...
Sat Nov 16, 2019 12:01 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Boiling Point
Replies: 6
Views: 104

### Re: Boiling Point

Arianna Perea 3H wrote:If it has more surface area, will the boiling point be higher?

The boiling point should be higher if the molecule has more surface area.
Fri Nov 15, 2019 10:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bent v. straight shape
Replies: 3
Views: 94

### Re: bent v. straight shape

In terms of repulsion strength, lone pair-lone pair experiences higher repulsion than lone pair-bonding pair, and lone pair-bonding pair experiences a higher repulsion than bonding pair-bonding pair. That means in order for the molecule to be bent, there must be lone pairs that push the bonding elec...
Sat Nov 09, 2019 3:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 4162

### Re: Rydberg equation[ENDORSED]

I don't think it really matters so long as you get the right answer, but I think Dr. Lavelle prefers that we use the one he taught in class because it allows us to conceptually understand what's occurring. Using his equation might also guarantee partial credit if you get part of the problem wrong, b...
Sat Nov 09, 2019 3:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 4162

### Re: Rydberg equation[ENDORSED]

I don't think it really matters so long as you get the right answer, but I think Dr. Lavelle prefers that we use the one he taught in class because it allows us to conceptually understand what's occurring. Using his equation might also guarantee partial credit if you get part of the problem wrong, b...
Sat Nov 09, 2019 3:10 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 12
Views: 273

### Re: Bond Strength

Covalent bonds are stronger than ionic bonds in an organic system because in an aqueous environment, the positive end of water molecules would surround the anion of an ionic compound and the negative end of water molecules would surround the cation of the ionic compound. In a vacuum however, the cov...
Sat Nov 09, 2019 2:06 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: H bonds and Intermolecular Forces
Replies: 4
Views: 102

### Re: H bonds and Intermolecular Forces

The intermolecular forces occur due to attraction of one atom to another atom, but they don't share electrons. Typically, intermolecular forces are indicated using dashed lines as opposed to a solid line because it is a weaker force than a chemical bond.
Sat Nov 09, 2019 1:35 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: Ion-Ion interactions
Replies: 5
Views: 42

### Re: Ion-Ion interactions

It should be between the individual ions, so in this case, between the Na+ and Cl- ions. Technically, I think they would be the strongest type of bond in a vacuum, but it is weaker than covalent bonds in water.
Fri Nov 08, 2019 12:09 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Intermolecular Forces 3F
Replies: 1
Views: 31

### Re: Intermolecular Forces 3F

I think the stronger the intermolecular force between the atoms, the higher the normal melting point because it'll take more energy to break the bonds. So like for the first one, I think NaCl has a higher melting point, but I'm not totally sure.
Sat Nov 02, 2019 6:21 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.9
Replies: 2
Views: 41

### Re: 2A.9

a) Co^2+

b) Fe^2+

c) Cr^2+

d) V^2+
Sat Nov 02, 2019 6:01 pm
Forum: Trends in The Periodic Table
Topic: Period Trends
Replies: 11
Views: 119

### Re: Period Trends

There's also ionic radius, which increases down a group and decreases across period.
Sat Nov 02, 2019 5:39 pm
Forum: Quantum Numbers and The H-Atom
Topic: 4th Quantum Number
Replies: 3
Views: 61

### Re: 4th Quantum Number

The fourth number is the spin, so you can either choose +1/2 or -1/2. It's arbitrary so long as you remember that no two electrons can have the same four quantum numbers, so if n, l, and ml are the same, you have to make sure one of the electrons has a ms value of 1/2 and the other has -1/2.
Sat Nov 02, 2019 4:38 pm
Forum: Trends in The Periodic Table
Topic: Noble Gases
Replies: 2
Views: 39

### Re: Noble Gases

I think that the noble gases are still subject to the trends for atomic radius and ionization energy, but I don't think that the other trends apply because noble gases are unlikely to lose or gain electrons.
Sat Nov 02, 2019 4:20 pm
Forum: DeBroglie Equation
Topic: Determining Wave-like Properties
Replies: 4
Views: 70

### Re: Determining Wave-like Properties

I'm still confused as to what the relationship between the deBroglie wavelength and the mass is? If an atom has a longer wavelength does that mean it has a lighter mass or? The debroglie wavelength and the mass is inversely proportional because the formula is wavelength equals h/mv. If the atom has...
Thu Oct 24, 2019 11:37 pm
Forum: Ionic & Covalent Bonds
Topic: Does the Octet Rule apply to Boron?
Replies: 14
Views: 155

### Re: Does the Octet Rule apply to Boron?

Sulfur is capable of forming 6 bonds as seen in SF6 but I'm not sure if we need to know that particular exception.
Thu Oct 24, 2019 11:28 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 7
Views: 242

### Re: Ionization Energy

I think the second ionization energy is higher than the first ionization energy because there's more effective nuclear charge. (I might be wrong though).
Thu Oct 24, 2019 11:13 pm
Forum: Octet Exceptions
Topic: 2A.21 Ground-state Electron Configuration
Replies: 2
Views: 38

### Re: 2A.21 Ground-state Electron Configuration

I think the configuration for Ag+ is 4d^10 because if the 5s state is already filled, the 4d state is more stable. I think it's because a half full d orbital or a full d orbital has less energy than an s orbital.
Thu Oct 24, 2019 10:55 pm
Forum: Properties of Electrons
Topic: Anions and Cations
Replies: 4
Views: 87

### Re: Anions and Cations

Anions are usually larger than cations because anions usually experience more shielding.
Thu Oct 24, 2019 10:09 pm
Forum: Octet Exceptions
Topic: Octet Rule
Replies: 6
Views: 64

### Re: Octet Rule

If the element is past the second period in the periodic table does it still need to follow the octet rule? Almost all atoms follow the octet rule because it's more stable, except for hydrogen, helium, lithium and beryllium. With those atoms, having a different number of bonds aids in the stability...
Sat Oct 19, 2019 6:54 pm
Forum: Properties of Light
Topic: Difference between photon vs particle
Replies: 5
Views: 66

### Re: Difference between photon vs particle

Photons also don't have a discernable mass while other particles do, so sometimes using photon over particle would be more specific.
Fri Oct 18, 2019 4:02 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: removing electrons
Replies: 5
Views: 382

### Re: removing electrons

You'd have to pull the electrons from the highest energy orbital. I think the outermost electrons are easier to remove because the outermost electrons experience less electrostatic attraction.
Thu Oct 17, 2019 11:02 pm
Forum: DeBroglie Equation
Topic: deBroglie, finding wavelike properties
Replies: 2
Views: 51

### Re: deBroglie, finding wavelike properties

You're missing one more conversion factor. There's 60 minutes in an hour, so you just forgot to multiply by 1 min/60 seconds. If you correct that mistake, you should get 34.72 m/s and then you plug that value into the equation. It shouldn't have wavelike properties because the answer gets you 6.94 x...
Thu Oct 17, 2019 10:21 pm
Forum: *Shrodinger Equation
Topic: Psi ^2
Replies: 2
Views: 39

### Re: Psi ^2

I think it's because the probability of finding an electron can't be negative? The trough of the wave would be considered negative if psi represents the height of the wave, so squaring it should make the probability positive (I think).
Thu Oct 17, 2019 10:01 pm
Forum: Properties of Light
Topic: Problem 1A.7
Replies: 5
Views: 86

### Re: Problem 1A.7

For the first question, you'd have to use c = wave length x frequency, so you'd divide 3 x 10^8 meters per second by 7.1 x 10^14 Hz. If it helps, 1 Hz is equivalent to 1/second, so your units should cancel out and leave you just your wavelength. After that, it's just a matter of converting the meter...
Sat Oct 12, 2019 1:53 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminacy principle
Replies: 3
Views: 315

### Re: Indeterminacy principle

The correct answer is that you can't be certain of the momentum and position of the particle simultaneously. It's basically the idea that by the time you determine the exact position of the particle at an exact time, you no longer have an idea of the momentum of the particle. Likewise, by the time y...
Sat Oct 12, 2019 1:30 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Intensity of Light
Replies: 7
Views: 87

### Re: Photoelectric Effect Intensity of Light

I think intensity is basically a measure of how many photons are available. With intensity, it usually correlates to the wave model of light, but frequency typically correlates with the photon model of light. Frequency is increased when wavelengths are shorter, but that has no correlation to the amp...
Fri Oct 11, 2019 3:13 pm
Forum: Significant Figures
Topic: Sig Figs in % Yield
Replies: 10
Views: 1032

### Re: Sig Figs in % Yield

When I am solving a problem, do I have to keep in mind the sigfigs throughout all the calculations? Or just keep the right sigfigs for the final answer. I think you just need to keep the same sig figs for the final answer because it's better for accuracy to round at the end. I'm pretty sure roundin...
Thu Oct 10, 2019 1:51 pm
Forum: Empirical & Molecular Formulas
Topic: post test problem
Replies: 3
Views: 200

### Re: post test problem

The law of conservation of mass should apply to all problems, so you should be able to subtract the mass of cobalt from the final compound's mass to find the mass of fluorine gas originally involved in the reaction. After finding the mass of the fluorine, you should be able to convert each of those ...
Thu Oct 10, 2019 1:43 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 17
Views: 627

### Re: Combustion

Combustion is an oxidation reaction, meaning it would involve oxygen because it receives an electron from the oxygen molecule. With most combustion reactions, they tend to form water and carbon dioxide.
Wed Oct 02, 2019 4:59 pm
Forum: Empirical & Molecular Formulas
Topic: QUESTION F3
Replies: 3
Views: 157

### Re: QUESTION F3

I think you're technically supposed to know it because it is basically a nitrate ion (NO3-) with an added hydrogen atom. It tends to come up fairly often in chemistry, so it's really helpful to have it memorized. Assuming that the polyatomic ion that is being protonated ends with -ate (like nitrate)...
Mon Sep 30, 2019 11:00 pm
Forum: Significant Figures
Topic: Determining significant figures on HW and quizzes/exams
Replies: 3
Views: 81

### Re: Determining significant figures on HW and quizzes/exams

I would assume that he'll grade us based on our significant figures because it determines the accuracy of measurements. The accuracy is really important for determining error because no scientific tool can ever determine a measurement perfectly; there's always some discrepancy.
Mon Sep 30, 2019 10:26 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Understanding Titrations
Replies: 3
Views: 89

### Re: Understanding Titrations

Titrations are essentially used to determine the molarity of a solution. If you had an unknown solution of some acid, you could use a basic solution with known concentration to determine the molarity of the acidic solution. You would add an indicator to the acidic solution and then continuously add ...
Mon Sep 30, 2019 10:13 pm
Forum: Empirical & Molecular Formulas
Topic: Percentage Yield
Replies: 3
Views: 56

### Re: Homework Problem M.1

Basically, the percentage yield is the amount of product in grams you have obtained through experimentation divided by the amount of product in grams you would get if no product was lost during the experiment. So first you'd have to convert the 35.0 grams of NH3 to moles using its molar mass and the...
Sat Sep 28, 2019 10:03 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Figuring out the names of things
Replies: 4
Views: 145

### Re: Figuring out the names of things

I think SnO2 is actually considered Tin (IV) oxide. You would have to look at the oxidation states of the individual atoms to determine if it was Tin (IV) or Tin (II). Oxygen tends to have an oxidation state of -2, and the oxidation state of neutral compounds is zero, so to be SnO2, the oxidation st...

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