## Search found 69 matches

Sat Jan 23, 2021 10:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to fill in 2nd row of ICE table?
Replies: 25
Views: 65

### Re: How to fill in 2nd row of ICE table?

In general, if the first row has a "0", then the second row will be adding x or 2x, etc But for a more formal look at this, you should compare Q and K. If Q < K, then the reaction needs more products, and will proceed to the right. So the products will have a +x or +2x etc while the produc...
Sat Jan 23, 2021 10:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exothermic and Endothermic Reactions
Replies: 9
Views: 33

### Re: Exothermic and Endothermic Reactions

Catie Donohue 2K wrote:So just to clarify what's already been said, catalysts control the speed of endothermic and exothermic reactions, but do not affect the change in enthalpy of the reaction?

Yes, that is correct :)
Sat Jan 23, 2021 9:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard State
Replies: 11
Views: 29

### Re: Standard State

Standard states are at 1 atm and 25 degrees Celsius. When trying to find the standard state of a molecule, if you cant look it up, I think we should just go with what we have seen in this class, like in previous problems in example. For example, N2 would be N2(g) and H would be H2(g), as these are w...
Sat Jan 23, 2021 9:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard states
Replies: 6
Views: 33

### Re: standard states

Hello! I think the ones he mentioned in class were He(g), Ar(g), N2(g), O2(g), F2(g), H2(g), Cl2(g), B2(l), I2(s), most stable form of carbon is graphite. I think in general we should just do what "feels right" or what we have seen before when trying to figure out the standard state in a p...
Sat Jan 23, 2021 9:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exothermic and Endothermic Reactions
Replies: 9
Views: 33

### Re: Exothermic and Endothermic Reactions

Catalyst speed up a chemical reaction by lowering the activation energy.

Enthalpy is a state property, so it does not depend on the path taken. Therefore, lowering the activate energy will not effect the net enthalpy.
Sat Jan 23, 2021 9:53 pm
Forum: Phase Changes & Related Calculations
Topic: Steam causing severe burns
Replies: 19
Views: 68

### Re: Steam causing severe burns

Yes! I think that since the steam first comes into contact with the air, and the system involving the steam is much hotter than the surrounding, the system naturally loses heat to the surroundings before it hits your face. Also, I feel that this would have to do with diffusion of this extremely hot ...
Fri Jan 15, 2021 11:34 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 45
Views: 123

### Re: Temperature

For endothermic Rxn (delta H is greater than 0, the forward reaction requires energy): increase temperature--> increases K --> the forward reaction is favored (reaction shifts to the right) decrease temperature --> decrease K --> reverse reaction is favored For exothermic reaction (delta H is negati...
Fri Jan 15, 2021 11:31 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #4
Replies: 7
Views: 64

### Re: Sapling #4

Yes, that is correct!

Now, you set the Kp expression you provided equal to the given K value. Also, set up an ice table with initial, change, and equilibrium concentrations to attain your quadratic, solve for x, and then you can find the equilibrium pressures for all species.
Fri Jan 15, 2021 11:29 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K on and reactant/product concentrations
Replies: 8
Views: 27

### Re: Q and K on and reactant/product concentrations

Q = [P] / [R], so if Q<K, there is no way that the reactant concentration could be greater than the products and Q be <K.
Fri Jan 15, 2021 11:27 am
Forum: Ideal Gases
Topic: Ice method
Replies: 14
Views: 68

### Re: Ice method

I= initial concentration C= change in concentration E= equilibrium concentration. For a balanced reaction, you have the initial concentrations of each species (given, or 0). Many times you have the equilibrium conc of one of the species, with which you can find the change in concentration for each s...
Fri Jan 15, 2021 11:24 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: lecture 5 question
Replies: 13
Views: 56

### Re: lecture 5 question

Yes, there are trends (like group 1 and 2 metal oxides/hydroxides are strong bases) and also specific strong acids and bases you should memorize, found in the textbook. When an acid protonates, it forms is conjugate base. When a base accepts the H+, it forms its conjugate acid. Heres an example: HCl...
Fri Jan 15, 2021 11:21 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 19
Views: 103

### Re: Le Chatelier's Principle

Le Chatelier's principle holds that when a change is exerted on a system (like changing the concentration or pressure by changing the volume), the system will respond in a way that will minimize that change and return to "normal" Example: For the reaction A+ B --> C. Assume this reaction i...
Fri Jan 08, 2021 11:01 am
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 288

### Re: Units of Temperature

We always use Kelvin for temperature in PV=nRT. This is simply because the units cancel out with the units of the other species in the equation.
Fri Jan 08, 2021 11:00 am
Forum: Ideal Gases
Topic: Ideal vs real gases
Replies: 12
Views: 59

### Re: Ideal vs real gases

I believe in lecture Dr. Lavelle said that an ideal gas is defined as a gas that does not undergo a phase change to a liquid when it is cooled. I believe that for this class, we assume all gases (assuming that they are a gas for a specific T and not a liquid that was cooled) are ideal and we can use...
Fri Jan 08, 2021 10:58 am
Forum: Ideal Gases
Topic: Bars to atm [ENDORSED]
Replies: 35
Views: 173

### Re: Bars to atm[ENDORSED]

One bar is about equal to one atm. There is a slight difference, but for the purpose of this class, you can use the two terms interchangeably.
Fri Jan 08, 2021 10:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE tables
Replies: 11
Views: 66

### Re: ICE tables

I= initial concentration. This is the concentration of each reactant and product (mol/L) that you start off with C= change in concentration. The reactant usually will have a decrease in concentration that is proportional to the increase in concentration in the product. If there is one mol of a react...
Fri Jan 08, 2021 10:52 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: names for reaction quotient Q
Replies: 19
Views: 68

### Re: names for reaction quotient Q

Q can mean either Qp or Qc. Qp uses the partial pressures of each species (raised to a certain power if necessary), and is when all the elements in the equation are all gases, as solids and liquids can't exert partial pressure. Qc uses molar concentrations of each reactant and product (exclude solve...
Fri Jan 08, 2021 10:50 am
Forum: Ideal Gases
Topic: Ideal Gas Law Question
Replies: 11
Views: 57

### Re: Ideal Gas Law Question

T is constant because the temperature does not change when you are using PV=nRT. Although temperature in general can change, when we use PV=nRT we assume a certain set of conditions, in which Temperature is a set value.
Sat Dec 12, 2020 4:06 pm
Forum: Octet Exceptions
Topic: Clarification on Expanded Octets
Replies: 3
Views: 15

### Re: Clarification on Expanded Octets

Expanded octet just means that an atom utilizes its d block to hold more than 8 electrons in the valence, which is not possible with only s and p orbitals. The common expanded octets are P, S, Cl. Any atom in row 3 of the periodic table (in the p block) and below, can have an expanded octet because ...
Sat Dec 12, 2020 4:04 pm
Forum: Hybridization
Topic: sp3 orbitals
Replies: 6
Views: 52

### Re: sp3 orbitals

The number in front is the energy level (n), or the principle quantum number. This specifies the different shells that the valence electrons are in.
Sat Dec 12, 2020 4:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw vs. trigonal pyramidal
Replies: 22
Views: 150

### Re: Seesaw vs. trigonal pyramidal

See saw is AX4E , while trigonal pyramidal is AX3E
Sat Dec 12, 2020 4:01 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Heme Complex Coordination Compound
Replies: 3
Views: 46

### Re: Heme Complex Coordination Compound

I think we just know that its square planar because Dr. Lavelle told us in class. Otherwise, theres no way to tell if somethings square planar vs tetrahedral if you cant see the Lone pairs. We know that only one O2 can bind to hemoglobin/the heme complex because the Fe is bonded to 4 N's and a hista...
Sat Dec 12, 2020 3:57 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Textbook Problem 6C.17
Replies: 2
Views: 13

### Re: Textbook Problem 6C.17

I was also confused about this explanation the textbook gave. I do not think we have the memorize the pKA values or anything, I think that they were just provided in the textbook and we were supposed to reference them. Assuming we were not given the pKA values, I said that BrO- would be the stronger...
Sat Dec 05, 2020 10:39 am
Forum: Biological Examples
Topic: chelates
Replies: 8
Views: 70

### Re: chelates

The quick answer is that whenever you see a compound with at least one polydenate ligand, that compound is a chelate. A chelate is a compound that is a ring-like structure, in which the polydenate ligand(s) form a ring which locks in the central TM atom. An example of a chelate is the heme complex. ...
Sat Dec 05, 2020 10:36 am
Forum: Hybridization
Topic: How to find the hybridization
Replies: 14
Views: 93

### Re: How to find the hybridization

Find the regions of electron density around that atom. Electron density refers to a Lone pair of electrons, or a bond (single, double, triple bonds all count as one region of electron density) If there is one region of e density - only uses s orbital two regions of e density- sp hybridization three ...
Sat Dec 05, 2020 10:33 am
Forum: Lewis Acids & Bases
Topic: Water
Replies: 62
Views: 492

### Re: Water

Water can act as an acid or base, it just depends. This makes sense if you think about Dr. Lavelle's discussion about how molecules do not just "choose" to be an acid or a base, and it depends on their chemical environment.
Sat Dec 05, 2020 10:31 am
Forum: Naming
Topic: Polydentate
Replies: 8
Views: 58

### Re: Polydentate

Polydenate means that the ligand binds with the TM more than once. So, polydendate ligands have at least 2 lone pairs, and they have to be long enough to stretch/bend in order to make 2/more coordinate covalent bonds with the TM. There needs to be single (Sigma) bonds that allow for this rotation. T...
Sat Dec 05, 2020 10:17 am
Forum: Naming
Topic: Naming Order
Replies: 16
Views: 62

### Re: Naming Order

For the chemical formula, the order does not really matter. Just make sure that you put the transition metal first, followed by all of the other ions and atoms.
Sat Nov 28, 2020 4:07 pm
Forum: Hybridization
Replies: 5
Views: 35

### Re: Question about Hybridized Orbitals

Hybridization is a "mixing" of atomic orbitals in terms of energy. So, the hybridized orbital sp^3 is a mixing of one s and 3 p orbitals in terms of energy. Since this is true, the sp^3 hybrid orbital will have more energy than an unhybridized s orbital and less energy than a hybridized p ...
Sat Nov 28, 2020 4:05 pm
Forum: Hybridization
Topic: e density
Replies: 30
Views: 138

### Re: e density

Yes, every bond is considered a region of electron density. Remember that a double bond and triple bond are bond considered one region of electron density, even though there is more than one bond.
Sat Nov 28, 2020 4:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: H2O VSEPR
Replies: 27
Views: 147

### Re: H2O VSEPR

it would be bent

there are 4 total electron density regions, with two being lone pair electrons and 2 being bonds
Sat Nov 28, 2020 4:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity and Shape
Replies: 13
Views: 93

### Re: Polarity and Shape

A molecule is polar if the dipoles on the diagram do not cancel out. So, the bonds themselves must be polar (there must be an electronegativity difference between the 2 atoms) and the bonds cannot cancel out, so there is a charge separation element too.
Sat Nov 28, 2020 4:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Delocalized Pi Bond
Replies: 7
Views: 38

### Re: Delocalized Pi Bond

delocalized pi bonds occur when the molecule with the pi bond has resonance. Remember that resonance structures have atoms that all have the same bond lengths. For a resonance structure with double and single bonds, the actual bond length is in between double and single. Because all bond lengths hav...
Sat Nov 28, 2020 3:51 pm
Forum: Hybridization
Topic: Hybridization Explanation
Replies: 6
Views: 73

### Re: Hybridization Explanation

Hybridization is a mathematical model that can be thought as a "mixing" of several orbitals in terms of energy. For ex, sp^2 hybridization creates a hybrid orbital that is a "mix" of one "s" and 2 "p" orbitals to create an sp^2 orbital that has an energy level...
Thu Nov 19, 2020 3:58 pm
Forum: Coordinate Covalent Bonds
Topic: Identifying Lewis Acid and Lewis Base
Replies: 3
Views: 57

### Re: Identifying Lewis Acid and Lewis Base

Lewis bases- donate an electron pair in coordinate covalent bond. For atoms without a charge, look for lone pairs on the atoms which can be easily donated. Lewis acids- accept a lone pair of electrons in a coordinate covalent bond. For atoms without a charge, look for atoms like B that do not have a...
Thu Nov 19, 2020 3:57 pm
Forum: Electronegativity
Topic: Periodic trend
Replies: 17
Views: 150

### Re: Periodic trend

Electronegative, electron affinity, and ionization energy all have the same trends. They increase across a period, and decrease down a group. ionization energy has one exception- O has a lower ionization energy than N for electron-electron repulsion reasons (N has 3 unpaired e's in its p subshell wh...
Thu Nov 19, 2020 3:54 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability vs Polarizing Power in anions/cations & bonding
Replies: 10
Views: 65

### Re: Polarizability vs Polarizing Power in anions/cations & bonding

Polarizability pertains to the anion. It is a measure of how easily their electrons can be distorted (and moved into the shared region, which is on the internuclear axis between two atoms in a bond). Larger anions have more electrons that are not as closely held to the nucleus, so they are more pola...
Thu Nov 19, 2020 3:51 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Best Formal Charge Equations
Replies: 24
Views: 133

### Re: Best Formal Charge Equations

The best way to calculate formal charge is (number of valence electrons) - (dots) - (lines). Professor Lavelle covered another formula in class, but the formula I provided gives the same answer and is a lot faster.
Thu Nov 19, 2020 3:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 16
Views: 260

### Re: bond angles

We can predict the bond angles using VSPR, which is based on electron electron repulsion between lone pair electrons and bonding pair electrons. In terms of finding the exact value of the bond angles, this may not be always known, as many times the angles are described as being "less than"...
Sat Nov 14, 2020 9:20 pm
Forum: Resonance Structures
Topic: bond length
Replies: 6
Views: 25

### Re: bond length

Look at the trends Bond length depends on the number of bonds (double, single, triple) and the size of the atoms You cant look at the periodic table for the number of bonds, but you can look for the size of the atoms atomic radius increases down a group (higher energy levels occupied with more elect...
Sat Nov 14, 2020 9:18 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: increasing polarizability
Replies: 5
Views: 48

### Re: increasing polarizability

Agreeing with what everyone has said, you look at the atomic radius (larger atomic radius means the electrons are less tightly held and more easily distorted). In terms of looking at this on the periodic table, Cl- is clearly the largest atom of all the ones on the list (because its on a lower perio...
Sat Nov 14, 2020 9:12 pm
Forum: Dipole Moments
Topic: Textbook discrepancy
Replies: 6
Views: 45

### Re: Textbook discrepancy

Hi, I was also confused about this. But, since in lecture and all of the peer review sessions they have the arrow pointing to the more electronegative atom, I think that we should use this as the standard. It makes sense because the arrow represents the pulling of the electrons, and the more electro...
Sat Nov 14, 2020 9:10 pm
Forum: Lewis Structures
Topic: Recognizing lowest formal charge
Replies: 11
Views: 50

### Re: Recognizing lowest formal charge

I dont think there is any set rule, but I like to draw the lewis structure with the lowest formal charge that I can think of and then quickly draw some other options just to make sure that it does in fact have the lowest possible formal charge. Helpful tips would be to make sure that the most electr...
Sat Nov 14, 2020 9:08 pm
Forum: Octet Exceptions
Topic: Octet Exceptions Rules
Replies: 3
Views: 23

### Re: Octet Exceptions Rules

The exceptions are: less than an octet: H, He- 2 electrons (usually) Li, Be - 4 electrons usually Al and Boron- won't always have less than an octet, but if they do they'll usually have 6 electrons in the valence radicals (7 valence e's) In terms of explaining this, it makes sense that H and He have...
Sun Nov 08, 2020 11:47 am
Forum: Formal Charge and Oxidation Numbers
Topic: Why do we use formal charge?
Replies: 14
Views: 116

### Re: Why do we use formal charge?

Usually, we are looking to draw a lewis structure with a formal charge equal to zero, because this is the most stable form. Many times there are many different possible ways we can bond atoms in a molecule via a lewis structure, so considering formal charge is the way to figure out the "correct...
Sun Nov 08, 2020 11:44 am
Forum: Resonance Structures
Topic: Bond lengths
Replies: 20
Views: 143

### Re: Bond lengths

I don't think that you have to do that, at least for this class! However, I know that a double bond is stronger than a single bond, so that may be why you draw the double bonds as shorter in some cases.
Sun Nov 08, 2020 11:43 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 11
Views: 347

### Re: Formal Charge

It doesn't matter if its an electron, formal charge is the # of valence e's - (# dots) - (#lines) to put it simply. So if you get -1 when you do this, the Formal Charge would be -1.
Sun Nov 08, 2020 11:42 am
Forum: Lewis Structures
Topic: Atom in the middle of a lewis structure
Replies: 7
Views: 40

### Re: Atom in the middle of a lewis structure

Lower ionization energy (and thus lower electronegativity) has more space to accept bonds/electrons. So, it goes in the middle because this atom generally has the highest number of bonds in the atom
Sun Nov 08, 2020 11:39 am
Forum: Ionic & Covalent Bonds
Replies: 38
Views: 224

As you move right across a period, the number of protons increases (positive charge). This positive charge "pulls in" the negative electrons, so the electrons are closer to the nucleus (where the protons are). Because the electrons are more pulled closer to the nucleus as the number of pro...
Fri Oct 30, 2020 9:36 am
Forum: Quantum Numbers and The H-Atom
Topic: Energy Level Excited
Replies: 8
Views: 69

### Re: Energy Level Excited

For an electron to be excited, it has to absorb a photon of light with a frequency (v) that matches the specific energy difference between two energy levels/shells. After the electron is excited, it will eventually come back down to the lower energy state, emitting a photon with the same frequency/e...
Fri Oct 30, 2020 9:31 am
Forum: *Shrodinger Equation
Topic: The Hamiltonian
Replies: 8
Views: 126

### Re: The Hamiltonian

The Hamiltonian of the wave function is equal to the energy of the wave function. Since the wave function is sin theta/cos theta, the Hamiltonian is taking the double derivative of the wave function (sin theta), which gives you back sin theta. because of this fact, you are given back the wave functi...
Fri Oct 30, 2020 9:28 am
Forum: Trends in The Periodic Table
Topic: In class question
Replies: 8
Views: 62

### Re: In class question

I believe that the measure of the atomic radius still exists, but at least for our purposes, we cannot calculate it from just a lone atom, only when it is interaction with another.
Fri Oct 30, 2020 9:27 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Plane Importance
Replies: 9
Views: 50

### Re: Nodal Plane Importance

The position of a nodal plane also further differentiates an orbital from another (px, py, pz for example). The position of the nodal plane implies how the orbital is shaped and oriented.
Fri Oct 30, 2020 9:25 am
Forum: Quantum Numbers and The H-Atom
Topic: quantum number 4
Replies: 6
Views: 67

### Re: quantum number 4

I think the biggest reason for knowing the fourth quantum number is to understand that no 2 electrons can have the same 4 quantum numbers in an atom. The fourth quantum number provides the direction of spin.
Sun Oct 25, 2020 10:16 am
Forum: Properties of Light
Topic: Wavelength
Replies: 14
Views: 91

### Re: Wavelength

The equations will give you the wavelength in meters (as long as all of the values you plug in are in SI units). However, you can give the answer in m or nm, but since our midterm is multiple choice, it should be clear which one they are asking for.
Sun Oct 25, 2020 10:14 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question about the Delta X and what it stands for
Replies: 6
Views: 53

### Re: Question about the Delta X and what it stands for

When it says delta x is equal to 10 m/s + or - 3, then the uncertainty in x would be 6

when it says delta x is 1% of the radius (or anything along these lines), take 1% of the specified value

When an electron or something is confined to the atom, the uncertainty is the diameter of the atom
Sun Oct 25, 2020 10:12 am
Forum: DeBroglie Equation
Topic: Light and momentum
Replies: 7
Views: 58

### Re: Light and momentum

Hi! Confirming what has already been said, light has momentum in the form of energy even though it does not have a mass. So, photons do have momentum but because they do not have mass, you cannot use the debroglie equation for a photon/EMR
Sun Oct 25, 2020 10:10 am
Forum: Properties of Electrons
Topic: intensity vs energy
Replies: 29
Views: 254

### Re: intensity vs energy

I went to a UA session about this, and the statement technically depends on whether light is acting like a wave or a particle. If light is acting like a particle, increasing intensity increases the amplitude of the wave, so it would increase energy. If light is acting like a wave, increasing intensi...
Sun Oct 25, 2020 10:08 am
Forum: Photoelectric Effect
Topic: Intensity vs. Frequency
Replies: 22
Views: 140

### Re: Intensity vs. Frequency

For a particle-model, increasing intensity means increasing the amplitude, which increases the energy. This refers to increasing the intensity (brightness) of the light For a wave-like model, increasing intensity does not increase the energy because the EMR is acting like a particle and not a wave. ...
Fri Oct 16, 2020 4:56 pm
Forum: Einstein Equation
Topic: E=hv vs E=pc?
Replies: 8
Views: 325

### Re: E=hv vs E=pc?

Both equations are valid for calculating the energy of the photon. You would use either equation depending on what variables you are given.
Fri Oct 16, 2020 4:54 pm
Forum: Properties of Light
Topic: "Intensity"
Replies: 20
Views: 134

### Re: "Intensity"

Here are the general rules: Light can have both wave and particle properties, both are valid, but we just refer to light as a wave or particle depending on the situation. When we say light is acting like a wave, increasing intensity means increasing the amplitude of the wave, which increases energy ...
Fri Oct 16, 2020 4:46 pm
Forum: DeBroglie Equation
Replies: 5
Views: 95

### Re: Question about post-module assessment

This is correct. Every day objects do not demonstrate diffraction patterns because their masses are large, so the value of their wavelength from the equation wavelength=h/momentum yields an extremely small wavelength. Because their wavelengths are so extremely small, we cannot measure/notice wavelik...
Fri Oct 16, 2020 4:43 pm
Forum: Properties of Electrons
Topic: Electron Transition
Replies: 7
Views: 36

### Re: Electron Transition

An electron transition means that an electron is either absorbing a photon (absorption) and going to a higher energy level (a higher n). An electron transition to a lower energy level entails the electron emitting a photon of light. The energy required or released for an electron to make an energy t...
Fri Oct 16, 2020 4:40 pm
Forum: Photoelectric Effect
Topic: photoelectric effect
Replies: 17
Views: 135

### Re: photoelectric effect

yes, the threshold energy is the same as the work function. remember that this is equal to the amount of energy that is required to remove from electron from a certain element/atom (ejecting it so that the electron is no longer associated with the atom).
Wed Oct 07, 2020 10:15 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Writing a Formula Based Off of Compound Name (E.9)
Replies: 6
Views: 71

### Re: Writing a Formula Based Off of Compound Name (E.9)

I also had this question. Fundamentals D (Nomenclature), which is part of the optional reading, is all about naming compounds and all the rules. It was very helpful and I would recommend looking at sections 1-4 if you're having difficulty because it really cleared it up for me!
Wed Oct 07, 2020 10:06 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E21 (molecules vs formula units)
Replies: 3
Views: 50

### E21 (molecules vs formula units)

E.21 Calculate the amount (in moles) and the number of molecules and formula units (or atoms, if indicated) in (a) 10.0 g of alumina, Al 2 O 3 ; (b) 25.92 mg of hydrogen fluoride, HF HF; (c) 1.55 mg of hydrogen peroxide, H 2 O 2 ; (d) 1.25 kg of glucose, C 6 H 12 O 6 ; (e) 4.37 g of nitrogen as N N ...
Wed Oct 07, 2020 9:55 pm
Forum: Molarity, Solutions, Dilutions
Topic: Solute versus solvent
Replies: 5
Views: 78

### Re: Solute versus solvent

Hi, like others have said, the solute is the substance that is dissolved in the solvent. Just a tip to remember when dealing with dilution problems- the moles/amount of solute stays the same before and after you dilute a solution, only the concentration of the solute changes. The solute concentratio...
Wed Oct 07, 2020 9:53 pm
Forum: Significant Figures
Topic: Which number determines sig figs of the answer?
Replies: 26
Views: 179

### Re: Which number determines sig figs of the answer?

Supporting what others have said, the number of sig figs depends. For multiplication and division, use the smallest number of overall sig figs. For addition and subtraction, you look at the smallest number of decimal places and
Wed Oct 07, 2020 9:49 pm
Forum: Significant Figures
Topic: intermediate calculations with sig figs
Replies: 8
Views: 75

### intermediate calculations with sig figs

I know the rules of sig figs, but when we have problems that requires multiple steps/calculations, should we follow the rules of sig figs for each step, or should we have numbers with more sig figs than what is technically allowed and just make sure the final answer has the correct number of sig figs?