## Search found 78 matches

Sun Jan 17, 2021 5:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Liquids (Solutes)
Replies: 7
Views: 14

### Re: Pure Liquids (Solutes)

Dr. Lavelle tells us to write the chemical reaction with the (l) or (aq), as an easier way to identify if something is a pure liquid. Typically problems will include the chemical reaction, specifying which of the reactants and products are liquids or solids, and which are aqueous and gases.
Sun Jan 17, 2021 5:42 pm
Forum: Ideal Gases
Topic: Inverse Kc
Replies: 28
Views: 59

### Re: Inverse Kc

Kc is the equilibrium constant, so we use it to describe the forward reaction. When we are describing the reverse reaction(when products are making the reactants), we will use 1/Kc to describe the equilibrium constant. Another two to remember are when we multiply the moles of the entire reaction by ...
Thu Jan 14, 2021 10:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solids and liquids in K expression
Replies: 7
Views: 32

### Re: solids and liquids in K expression

We do not use solids or liquids because they do not have concentration. We will include all gases, and aqueous solutions as well because they have concentration (we can calculate their molarity)
Thu Jan 14, 2021 10:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O as a Gas
Replies: 53
Views: 374

### Re: H2O as a Gas

We do not exclude any gases. We will only exclude H2O when it is in liquid form. All liquids and solids are excluded because they do not have concentration. All gases and aqueous solutions will be included in the equilibrium constant/expression.
Thu Jan 14, 2021 10:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Getting two positive x values when using quadratic
Replies: 43
Views: 157

### Re: Getting two positive x values when using quadratic

From all the examples we have done so far, when there are two positive values, one of the x values will be larger than the initial concentration we need to subtract x from. Since it's not possible to have a negative concentration, the one that is smaller than the initial concentration will be the an...
Thu Jan 14, 2021 10:08 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Which Acids and Bases to remember
Replies: 3
Views: 30

### Re: Which Acids and Bases to remember

Since we will probably be dealing with weak acids and bases this quarter, every acid and base that is not part of the strong acids and bases is a weak acid/base. So the strong acids are HCl, HClO4, HClO3, HNO3, HBr, HI, H2SO4. and the strong bases are the groups one and two metal oxides.
Thu Jan 14, 2021 10:03 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: What is the Conjugate Seesaw
Replies: 10
Views: 59

### Re: What is the Conjugate Seesaw

The conjugate seesaw essentially says
- the stronger the acid, the weaker the conjugate base.
- the stronger the base, the weaker the conjugate acid.
- the weaker the acid, the stronger the conjugate base
- the weaker the base, the stronger the conjugate acid.
Fri Jan 08, 2021 11:53 am
Forum: Ideal Gases
Topic: Chemical Equilibrium Part 1A Post-Module Assessment
Replies: 11
Views: 25

### Re: Chemical Equilibrium Part 1A Post-Module Assessment

The answer is C, because even during equilibrium, there are chemical reactions happening at a "molecular level." Equilibrium is achieved when the rate of the forward reaction equals the reverse reaction, therefore C is false.
Tue Jan 05, 2021 10:55 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 109
Views: 913

### Re: Kc vs Kp

Depends on what the problem gives you. If it gives you units in bar/atm, it will most likely be Kp. If it gives you units in M or x moles in x L, it will probably be Kc.
Tue Jan 05, 2021 10:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Molar Ratios and ICE box
Replies: 3
Views: 21

### Re: Molar Ratios and ICE box

It's easier to use whole numbers because you will usually end up with a quadratic equation already, and it's easier to calculate when you have as many whole numbers as possible. Theoretically though, you could, as long as you don't mind the decimals.
Tue Jan 05, 2021 10:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc favoring products
Replies: 10
Views: 75

### Re: Kc favoring products

Yes, if the number is between 10^-3(or 10^-4 in some cases) and 10^3, they are not strongly favoring neither reactants or products.
Tue Jan 05, 2021 10:07 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 287

### Re: Units of Temperature

We should be using Kelvins
Tue Jan 05, 2021 10:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Kc
Replies: 15
Views: 80

### Re: K vs. Kc

K is the equilibrium constant and can be Kp or Kc. Kc is used for concentrations.
Sat Dec 12, 2020 4:28 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why isn't HF a strong acid?
Replies: 23
Views: 137

### Re: Why isn't HF a strong acid?

F is very electronegative, so the bond between H and F are stronger than with the other H-halogen acids, which means its a weaker acid!
Wed Dec 09, 2020 1:51 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: H3O+ versus H+
Replies: 16
Views: 113

### Re: H3O+ versus H+

They are basically the same thing. When we say we donate a proton, typically means donating an H+ which will form H3O+, so theyre essentially saying the same thing.
Wed Dec 09, 2020 1:49 pm
Forum: Identifying Acidic & Basic Salts
Topic: Titration Diagram
Replies: 5
Views: 21

### Re: Titration Diagram

ABCDE were just points in the data collection where S is the pH at 7 where the solution is at the stoichiometric point.
Wed Dec 09, 2020 1:48 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sapling #12
Replies: 7
Views: 32

### Re: Sapling #12

The more oxygen atoms there are, the stronger the acid.
Wed Dec 09, 2020 1:47 pm
Forum: Bronsted Acids & Bases
Topic: HF
Replies: 15
Views: 105

### Re: HF

The bond between HF is very strong because F is very electronegative. A strong acid dissociates/ionizes almost completely. It would be hard for the aqueous solution to dissociate HF, therefore it is not a strong acid.
Wed Dec 09, 2020 1:46 pm
Forum: Student Social/Study Group
Topic: lecture bruincast #29 problem
Replies: 10
Views: 88

### Re: lecture bruincast #29 problem

I also had this problem with today's lecture. I took a break and refreshed it 40 minutes later and it was fine again. It might be due to the amount of people on CCLE since finals are coming up.
Wed Dec 09, 2020 1:45 pm
Forum: Bronsted Acids & Bases
Topic: Ions as Bases/Acids
Replies: 3
Views: 37

### Re: Ions as Bases/Acids

In terms of looking at salts, you can tell which salts will behave as acids or bases. For example, NH4+ Cl- + H2O -> NH3 + H3O+ Cl-, chlorine does not affect the pH which means it has no effect as an acid or base. However, H3O+ concentration increases, which lowers the pH. You will need to see whic...
Wed Dec 09, 2020 1:43 pm
Forum: Polyprotic Acids & Bases
Topic: CO2 + H2O
Replies: 7
Views: 59

### Re: CO2 + H2O

CO2 and H20 mix to make carbonic acid which is H2CO3. H2CO3 can give off protons and become HCO3-, another common acid (bicarbonate).
Wed Dec 09, 2020 1:40 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 25 degrees celsius [ENDORSED]
Replies: 6
Views: 37

### Re: 25 degrees celsius[ENDORSED]

25 degrees is considered the standard, much like we consider room temperature.
Wed Dec 09, 2020 1:40 pm
Forum: Identifying Acidic & Basic Salts
Topic: Na2SO4 - Basic or Neutral?
Replies: 2
Views: 32

### Re: Na2SO4 - Basic or Neutral?

Na2SO42- would be the neutral salt that occurs when the strong acid and strong base are combined into one solution. The result of the combination of a strong acid and strong base would be the salt and H20 at the stoichiometric point where the pH is neutral
Sun Dec 06, 2020 8:55 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 4
Views: 27

### Coordination Number

In the textbook problems that Dr. Lavelle has assigned, specifically 9C.9, it asks us to determine the coordination number of the metal ion in the following complexes. For c and d, it gives [PtCl2(en)2]^2+ and [Cr(edta)]^-. Without knowing the structure and formula of ethylenediamine and EDTA, how w...
Sun Dec 06, 2020 7:19 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number
Replies: 14
Views: 99

### Re: Finding Coordination Number

You see how many bonds are formed with the Transition metal, by counting the number of atoms/molecules inside the square brackets.
Thu Dec 03, 2020 12:35 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid strength and bond length
Replies: 11
Views: 87

### Re: Acid strength and bond length

The longer the bond length, the weaker the bond, which means it is more easily dissociated/ionized. In lecture, Dr. Lavelle said that strong acids are almost completely ionized/dissociate in solution, therefore the longer the bond, the stronger the acid. (In most cases)
Thu Dec 03, 2020 12:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number
Replies: 14
Views: 99

### Re: Finding Coordination Number

The coordination number is the number of ligands attached to the central TM atom, which is essentially the stuff inside the square brackets.
Thu Dec 03, 2020 12:29 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acids Strength
Replies: 3
Views: 28

### Re: Bronsted Acids Strength

A strong acid(or even base) is almost completely ionized/dissociated in solution. The longer the bond, the more easily the acid dissociates, which is why HBr would be a stronger acid than HCl
Thu Dec 03, 2020 12:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 8
Views: 54

### Re: Coordination Number

coordination number is the number of ligands attached to the transition metal, essentially the atoms inside the square brackets.
Thu Dec 03, 2020 12:25 pm
Forum: Biological Examples
Topic: Hemoglobin vs. Myoglobin
Replies: 29
Views: 220

### Re: Hemoglobin vs. Myoglobin

Hemoglobin is in blood, and myoglobin is in tissue ie. muscles etc. essentially myoglobin gets oxygen from hemoglobin, and hemoglobin gets oxygen when it passes through our lungs when we breathe in the oxygen, the local partial pressure of oxygen is the highest in the lungs which is why hemoglobin b...
Sun Nov 29, 2020 7:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent
Replies: 9
Views: 62

### Re: Bent

Yes, bent and angular are both terms used for that shape.
Sun Nov 29, 2020 7:14 pm
Forum: Ionic & Covalent Bonds
Topic: Homework due date
Replies: 49
Views: 336

### Re: Homework due date

The hw is due on Sunday at 23.59!
Sun Nov 29, 2020 7:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: #13 Sapling Week 8
Replies: 18
Views: 99

### Re: #13 Sapling Week 8

Tetrahedral should be correct, maybe check your spelling!
Wed Nov 25, 2020 11:34 pm
Forum: Hybridization
Topic: UA Workshop Number 6a
Replies: 4
Views: 66

### Re: UA Workshop Number 6a

It is sp^2 because there are three regions of electron density. The double bond with the other N, the lone pair, and the single bond with C. The double bond still counts as 1 region of electron density, so there are 3 regions which means it is sp^2.
Wed Nov 25, 2020 3:03 pm
Forum: Lewis Structures
Topic: NO2 Polarity
Replies: 6
Views: 54

### Re: NO2 Polarity

The dipole moments do not cancel out in NO2 similarly to SO2, but unlike CO2 because CO2 has a linear shape. NO2 and SO2 both have lone pairs, which due to electron repulsion cause the shape to be bent/angular, therefore the dipole vectors do not completely cancel out and you will have a polar molec...
Wed Nov 25, 2020 2:58 pm
Forum: Bond Lengths & Energies
Topic: Tetrahedral Bond Angle
Replies: 6
Views: 78

### Re: Tetrahedral Bond Angle

We should know the approximate angle, ie. greater than, less than 109.5, etc.
Wed Nov 25, 2020 2:47 pm
Forum: Lewis Structures
Topic: Most Stable Structure
Replies: 23
Views: 117

### Re: Most Stable Structure

The most stable lewis structure is the structure with the lowest formal charge. The more electronegative atoms would be more likely to hold the negative formal charge in the molecule.
Wed Nov 25, 2020 2:46 pm
Forum: Dipole Moments
Topic: Negative Pole
Replies: 7
Views: 58

### Re: Negative Pole

You would look at the electronegativity of the atoms. The most electronegative would be the more negative pole of the dipole moment.
Sat Nov 21, 2020 5:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names
Replies: 50
Views: 299

### Re: Shape Names

This kind of shape can be called angular or bent.
Sat Nov 21, 2020 5:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 9
Views: 61

### Re: Bond Angle

Bond angles will depend on what molecule you are examining.
Sat Nov 21, 2020 5:32 pm
Forum: Ionic & Covalent Bonds
Topic: Polar Bonds
Replies: 19
Views: 109

### Re: Polar Bonds

You would draw the dipole moments on the lewis structure(by determining en) and then using vector addition, you could see which of the dipole moments cancel.
Sat Nov 21, 2020 5:30 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Non-Polar Bonds
Replies: 3
Views: 41

### Re: Non-Polar Bonds

Hydrocarbons are typically nonpolar, and molecules that have cancelling dipole moments are also nonpolar. It would be much more efficient to know how to draw the lewis structures and the dipole moments to know which cancel out.
Sat Nov 21, 2020 5:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair E-
Replies: 47
Views: 263

### Re: Lone Pair E-

Lone pairs count as e- density regions as well.
Fri Nov 13, 2020 9:07 pm
Forum: Lewis Structures
Topic: Recognizing lowest formal charge
Replies: 11
Views: 50

### Re: Recognizing lowest formal charge

calculate the number of electrons, then find the atom with lowest ionization energy to put in the center, then find the number of lone pairs on the central atom and how many bonds the central atom forms, and then you draw the structure out with as much symmetry as possible. Then you can calculate th...
Fri Nov 13, 2020 9:03 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook problem 2D. 5
Replies: 2
Views: 24

### Re: Textbook problem 2D. 5

The electronegativity of H is 2.2, F is 4.0(the most electronegative element), and C is 2.6. The EN difference between C and H is only 0.4 while the EN difference between C and F is 1.4. So CH4 could even be classified as a nonpolar covalent bond, while CF4 would display more ionic character.
Fri Nov 13, 2020 8:59 pm
Forum: Dipole Moments
Topic: Dipole dipole vs LDF
Replies: 10
Views: 59

### Re: Dipole dipole vs LDF

These are both intermolecular forces, but LDF and dipole-dipole are different. LDF could be used interchangably with induced dipole-induced dipole/van der waals forces/dispersion.
Thu Nov 12, 2020 11:54 am
Forum: Lewis Structures
Replies: 12
Views: 38

Radicals have an unpaired electron, you can usually tell when the total number of valence electrons you calculate out before you draw the lewis structure are odd.
Thu Nov 12, 2020 11:52 am
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge and stability
Replies: 8
Views: 55

### Re: formal charge and stability

It is of course best for the whole structure to have a formal charge of 0, but if that doesn't happen, i think the second most stable form is when the central atom has a formal charge of 0.
Thu Nov 12, 2020 11:47 am
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating Formal Charge
Replies: 9
Views: 98

### Re: Calculating Formal Charge

The equation is the most straightforward way to find the formal charge and find the most stable lewis structure.
Sat Nov 07, 2020 9:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Textbook 1D #21
Replies: 5
Views: 29

### Re: Textbook 1D #21

n gives the energy level, and every orbital can hold up to two electrons. l=0 would correspond to s sublevel, l=1 would be p, l=2 would be d, and l=3 would be f, etc. for instance, n=5 l=2 would be 5d based on the definition we gave for n and l.
Sat Nov 07, 2020 9:03 pm
Forum: Electronegativity
Topic: Electronegativity Table/Chart in Lecture
Replies: 14
Views: 53

### Re: Electronegativity Table/Chart in Lecture

We will need to know the trends, but it is not expected of us to memorize the specific electronegativity of each element.
Sat Nov 07, 2020 9:00 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Can you have the same 3 quantem number but not the 4 same quantem numbers
Replies: 12
Views: 63

### Re: Can you have the same 3 quantem number but not the 4 same quantem numbers

Yes, the first three quantum numbers can be the same, but the fourth must be different as each electron on that orbital would have a different spin.
Fri Nov 06, 2020 10:24 pm
Forum: Lewis Structures
Topic: Lewis Bases and Lone Pair Electrons
Replies: 3
Views: 33

### Re: Lewis Bases and Lone Pair Electrons

In the example Dr. Lavelle gave during lecture, the lone pair donor(lewis base) was NH3 and it was on the N atom, and the lone pair acceptor(lewis acid) is B from BF3.
Fri Nov 06, 2020 10:19 pm
Forum: Electronegativity
Topic: Shielding Effect
Replies: 6
Views: 34

### Re: Shielding Effect

Lucy's analogy of people standing around the fire pit is a good example! Since s-orbitals are closer to the nucleus, they are more effective at shielding.
Fri Nov 06, 2020 10:16 pm
Forum: Ionic & Covalent Bonds
Topic: Homework due date
Replies: 49
Views: 336

### Re: Homework due date

Sunday at 11.59 pm or 23.59.
Fri Nov 06, 2020 10:14 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 20
Views: 143

### Re: Bond lengths

We don't have to draw them to be longer vs shorter, but we should know double bonds are shorter and single bonds are longer.
Fri Nov 06, 2020 10:03 pm
Forum: Student Social/Study Group
Topic: Making it through Midterm Results
Replies: 13
Views: 141

### Re: Making it through Midterm Results

Honestly, going to UA sessions and office hours is super helpful. Going through each of Dr. Lavelle's lectures and processing the information, and then APPLYING the actual stuff we learned is also important. Doing all the homework problems in the outlines. Going to as many UA sessions as possible re...
Fri Oct 30, 2020 1:32 pm
Forum: Lewis Structures
Topic: Using Lewis Structures
Replies: 7
Views: 62

### Re: Using Lewis Structures

Yes, during lecture 12(10/30), Dr. Lavelle used the example of Potassium Chloride to show the lewis structure of an ionic compound.
Fri Oct 30, 2020 1:25 pm
Forum: Lewis Structures
Topic: Line in place of paired dots
Replies: 8
Views: 43

### Re: Line in place of paired dots

It's probably better to draw the lone pairs as pairs of dots, and to leave the lines to denote bonds.
Fri Oct 30, 2020 1:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 15
Views: 93

### Re: Electron Configurations

Dr. Lavelle has said that he would prefer for us to use the longer notation because it will tell us more about the configuration ie. which orbital the electron is occupying rather than writing 2p3.
Fri Oct 30, 2020 1:19 pm
Forum: Ionic & Covalent Bonds
Topic: Nonpolar and polar
Replies: 16
Views: 273

### Re: Nonpolar and polar

A polar covalent bond occurs when electrons are shared unequally, so if the difference in electronegativity is greater than or equal to 0.5, the bond is polar. A nonpolar covalent bond occurs when the atoms bonded together are of relatively similar electronegativies.
Fri Oct 30, 2020 1:15 pm
Forum: Lewis Structures
Topic: 10/30 lecture
Replies: 6
Views: 56

### Re: 10/30 lecture

Dr. Lavelle multiplied the number of oxygen valence electrons by 4 because there are 4 oxygen atoms in sulfate. In ammonium, there are 4 hydrogen atoms bonded to a nitrogen atom, therefore Dr. Lavelle multiplied the hydrogen valence electrons by 4.
Thu Oct 22, 2020 10:39 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation and its Fundamental Equation
Replies: 8
Views: 41

### Re: Rydberg Equation and its Fundamental Equation

Dr. Lavelle wants us to use $En=\frac{-hR}{n^{2}}$ precisely because it is easy to mix up the n1 and n2. In the equation he gives us, it is E=nfinal- ninitial.
Thu Oct 22, 2020 10:34 am
Forum: Properties of Light
Topic: Specifics on Light
Replies: 5
Views: 58

### Re: Specifics on Light

Yes, we should know the relative regions and order for the test, because that will not be given to us.
Thu Oct 22, 2020 10:32 am
Forum: Photoelectric Effect
Topic: Do we need to know about the Paschen or Brackett series for midterm 1?
Replies: 7
Views: 101

### Re: Do we need to know about the Paschen or Brackett series for midterm 1?

Dr. Lavelle has said during lecture that we will mostly be dealing with UV, visible, and infrared regions, so that would be Lyman, Balmer, and Paschen series. It might also be good to know that n=4 is the Brackett series
Wed Oct 21, 2020 9:44 pm
Forum: DeBroglie Equation
Topic: 1B.15 part b and c.
Replies: 3
Views: 45

### Re: 1B.15 part b and c.

For 1B.15 part b, you use the E=h\nu which is E=(6.626x10^{-34}J.s)(2.50x10^{16}s^{-1}) = 1.66x10^{-17}J , and since no electrons are emitted until frequency reaches 2.50x10^{16}s^{-1} , we can assume that is the work function. For part c, you use E(photon)= work function + E...
Wed Oct 21, 2020 9:34 pm
Forum: Properties of Light
Topic: N2 vs N1
Replies: 6
Views: 67

### Re: N2 vs N1

remember $\Delta E$ is Efinal - Einitial, so n2 is initial energy level and n1 is final energy level.
Thu Oct 15, 2020 8:48 pm
Forum: Einstein Equation
Topic: Einstein Equation
Replies: 10
Views: 223

### Re: Einstein Equation

E= hv

h= planck's constant $6.626*10^{-34}J.s$

v(nu)= frequency (Hz or $s^{-1}$)
Thu Oct 15, 2020 8:45 pm
Forum: SI Units, Unit Conversions
Topic: Webcam
Replies: 11
Views: 126

### Re: Webcam

Dr. Lavelle just sent an email out regarding the necessary equipment.
Thu Oct 15, 2020 8:38 pm
Forum: Photoelectric Effect
Topic: 1B #7 part b
Replies: 5
Views: 53

### Re: 1B #7 part b

\frac{5.00 mg Na}{1}\cdot \frac{1 g}{1000 mg}\cdot \frac{1 mol Na}{22.99g Na}\cdot \frac{6.022*10^{23}atoms}{1 mol Na}\cdot \frac{3.37*10^{-19}J}{1}= 44.1 J 1. you take 5.00 mg and get grams of Na 2. divide by the molar mass of Na (22.99) 3. multiply by avogadro's number to get amount of Na atoms i...
Thu Oct 15, 2020 8:30 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer and Lyman Series
Replies: 4
Views: 61

### Re: Balmer and Lyman Series

the Paschen series is in the infrared region.
Wed Oct 14, 2020 8:52 pm
Forum: Properties of Light
Topic: Exercise 1A.7
Replies: 4
Views: 49

### Re: Exercise 1A.7

1 Hz= s^-1, so (m/s)/s^-1, so m/s x s, which cancels out s to get m for wavelength.
Wed Oct 14, 2020 8:47 pm
Forum: Photoelectric Effect
Topic: Electron not emitted even for high intensity light
Replies: 9
Views: 92

### Re: Electron not emitted even for high intensity light

Energy(photon) must be greater or equal to work function in order for an electron to be emitted. if light only had wave properties, then increasing intensity should eject electrons(in wave model, intensity would be amplitude), but we need to consider light as photons(packets) of energy. So frequency...
Mon Oct 05, 2020 5:46 pm
Forum: Significant Figures
Topic: Sig Figs
Replies: 11
Views: 118

### Re: Sig Figs

there are four sigfigs. the leading zeroes don't count as significant figures.
Mon Oct 05, 2020 5:46 pm
Forum: Balancing Chemical Reactions
Topic: Reaction Terminology "In excess"
Replies: 11
Views: 129

### Re: Reaction Terminology "In excess"

In excess basically means that there is more than enough of this element to react, and that the other reactant is the limiting reactant.
Mon Oct 05, 2020 5:43 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity Question from Lecture 10/5
Replies: 5
Views: 82

### Re: Molarity Question from Lecture 10/5

The moles at the bottom are describing the stoichiometric coefficients. As you can see in the reactants, there are 4 mol of H as 2mol of H20 = 2mol H2 which is 4 mol of H. And then at the right hand side, there are 2 mol of NaOH and H2, which means that there are 2 mol of H in the NaOH and 2 mol H i...
Mon Oct 05, 2020 5:37 pm
Forum: Balancing Chemical Reactions
Topic: HW L35 Question: Using Mole Ratios to predict mass of product
Replies: 2
Views: 53

### Re: HW L35 Question: Using Mole Ratios to predict mass of product

I started by balancing the equations which I see you already did. Then you take 2.50 t and multiply by 1000 kg/1t and 1000 g/1kg to get the mass in grams. Next you multiply by 1 mol NaBr/102.9 g NaBr (so divide by the molar mass of NaBr to get the moles of NaBr) and then you multiply 1 mol Fe3Br8/8 ...
Mon Oct 05, 2020 5:31 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamentals M. 19
Replies: 6
Views: 69

### Re: Fundamentals M. 19

Nitrogen gas is a diatomic element, along with 6 other elements that are classified as Halogens.