## Search found 66 matches

Fri Jan 22, 2021 7:53 am
Forum: Phase Changes & Related Calculations
Topic: Phase Changes of Water Graph
Replies: 7
Views: 47

### Re: Phase Changes of Water Graph

The line just represents the heat's increase but not the direct or exact number. I would say the graph is just trying to represent a proportional relationship to the higher phase change and a higher temperature. The more heat or energy you have, the higher up the phase change (fusion to sublimation)...
Fri Jan 22, 2021 7:50 am
Forum: Phase Changes & Related Calculations
Topic: phase transition
Replies: 13
Views: 46

### Re: phase transition

The temperature is still constant since all of the heat goes into breaking the bonds of the material rather than physically heating up the material. That is why there is a constant line, which is basically the material transforming into another phase.
Fri Jan 22, 2021 7:48 am
Forum: Phase Changes & Related Calculations
Topic: Endothermic v. Exothermic
Replies: 61
Views: 166

### Re: Endothermic v. Exothermic

Yes, I would say so in my opinion but I don't know if there any exceptions out there. To be clear, sublimation, vaporization, and fusion all are endothermic to begin with and you have to add heat to the system for there to be a phase change from ice to steam, that is why they all have positive delta...
Fri Jan 22, 2021 7:41 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: What is Qp?
Replies: 5
Views: 25

### Re: What is Qp?

qp is basically representing the heat of the system so with a greater change in enthalpy or a positive change in enthalpy, the heat of the system increases, and it is an endothermic system. This is because the change in enthalpy usually refers to the system.
Fri Jan 22, 2021 7:37 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess Law
Replies: 10
Views: 158

### Re: Hess Law

For the Hess Law, we basically have to manipulate the equation so that it matches the specific final reaction we want. The real first step is to write the chemical formula for what the question wants and to balance it. Then, take the other formula given and create a formula in which the stoichiometr...
Fri Jan 15, 2021 5:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Gas
Replies: 16
Views: 78

### Re: Gas

Gases for the partial pressure use atm and bars interchangeably (since they are basically the same value/ a lot like Watts and Joules if that makes any sense). It's just that our books use bars rather than atm. more often.
Fri Jan 15, 2021 5:18 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O as a Gas
Replies: 69
Views: 408

### Re: H2O as a Gas

Generally, you would include it if it was a gas and if it is NOT a solvent (meaning it is on both sides of the equation since (aq) means something + H2O).
Fri Jan 15, 2021 5:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When x is negligible in Equilibrium constant
Replies: 34
Views: 110

### Re: When x is negligible in Equilibrium constant

According to the latest lecture, an easy way to determine this is if the K value is less than 10^-4 or if the x value is less than 5% of the initial value. I think just using the guideline of when K<10^-4 is better considering you won't have to find the x value from the approximation method first an...
Fri Jan 15, 2021 5:11 pm
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

Actually, when Q<K it is always the case that the reaction is a forward reaction since more products are formed than reactants, so [P] is always greater than [R]. I don't get where you got the info that [R]> [P] when Q<K since [R] is decreasing. In the questions having to do with Le Chatelier's prin...
Fri Jan 15, 2021 5:04 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Using Kw
Replies: 5
Views: 28

### Re: Using Kw

We use Kw (1*10^-14) whenever we are dealing with the concentrations of hydronium and hydroxide ions, so basically when it comes to any reactions involving aqueous solutions. For instance, if we were asked for the hydronium concentration from the hydroxide concentration or if we were asked for their...
Fri Jan 08, 2021 9:10 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Part 3 Post Module Assessment #19
Replies: 4
Views: 29

### Re: Part 3 Post Module Assessment #19

Make sure that you divided the mole values of the products and reactants by the 3.00 liters of the vessel mentioned in the problem before you plug it into the icebox. This was a mistake I made the first time. Remember that the concentration is in moles per liter and not just moles. Hopefully, then y...
Fri Jan 08, 2021 9:06 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K vs. Q in experiments
Replies: 2
Views: 51

### Re: K vs. Q in experiments

So to put it simply, K is when the reaction or system is at equilibrium and the concentrations of the reactants and products can be anything but they don't change further (for instance product concentrations can be greater than reactants or vice versa). What is important to note is that the concentr...
Fri Jan 08, 2021 9:00 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Water
Replies: 28
Views: 102

### Re: Water

Well, it depends on what state H2O (when it is in liquid form it cancels out) is in. However, I would like to add is that H2O can also be used as a solvent and is placed on both sides of the equation in liquid form so when you write the K constant the concentrations cancel out. When H2O is in gas fo...
Fri Jan 08, 2021 8:54 am
Forum: Ideal Gases
Topic: Chemical Equilibrium Part 1A Post-Module Assessment
Replies: 11
Views: 27

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

The correct answer is that there is no reaction occurring (which is not true!). Whenever something is at equilibrium is means that there is no NET change of the concentrations of products and reactants but their values might slightly change due to small, almost unnoticeable perturbations. But, to be...
Fri Jan 08, 2021 8:51 am
Forum: Ideal Gases
Topic: Gas constant R
Replies: 26
Views: 105

### Re: Gas constant R

The constant of R is the ideal gas constant and you don't need to memorize anything regarding constants considering that they are all on the equations sheet. In terms of using the constant, the units tend to shift on whether you have the molar concentration (L*mol-1*K-1*atm)of something or you have ...
Mon Dec 07, 2020 8:16 am
Forum: Ionic & Covalent Bonds
Topic: Valence in d-block
Replies: 4
Views: 34

### Re: Valence in d-block

So when you are taking into account the d block, you would count its valence electrons just like you would do for the s and p block, just make sure that for the 4th period, you count the d-block as it overlaps with the s and p blocks at that rate. Now, the only thing you would do differently, in ter...
Mon Dec 07, 2020 8:09 am
Forum: Quantum Numbers and The H-Atom
Topic: n=6,l=5
Replies: 6
Views: 81

### Re: n=6,l=5

Theoretically, that would work considering that the l number is one less than the n number. l is always one less than the n number considering it is a subshell of it.
Mon Dec 07, 2020 8:07 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: d orbitals
Replies: 7
Views: 70

### Re: d orbitals

So basically, d orbitals are only present and empty in the elements from the 3rd period to beyond. This is especially useful to know for Lewis structures since that means the central atom can hold more than eight electrons forming something greater than an octet. The orbital itself has one node (whe...
Mon Dec 07, 2020 7:59 am
Forum: DeBroglie Equation
Replies: 21
Views: 129

Avogadro's number is approximated by 6.022*10^23 and it basically represents the number of atoms in a mole of any element which is different from the individual atomic mass. You can multiply the moles of something by Avogadro's number to get the atom amount of it. You can divide by Avogadro's number...
Mon Dec 07, 2020 7:55 am
Topic: What if I want to know more?
Replies: 2
Views: 42

### Re: What if I want to know more?

Black body radiation refers to the idea that if heated to various high temperatures, a black body (which cannot be seen) can emit different or multiple wavelengths of light. In this way, it connects more to the wave theory or wave property of electromagnetic radiation rather than the particle proper...
Mon Nov 30, 2020 8:32 am
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 7
Views: 54

### Re: Hybrid Orbitals

You can use hybrid orbitals to determine the amount of bonding that occurs between central atoms and some surrounding atoms. It's kind of a confirmation of the electron arrangement of the molecule and helps you see clearly if there are any pi or sigma bonds involved. You basically find the electron ...
Mon Nov 30, 2020 8:27 am
Forum: Hybridization
Topic: sp^3
Replies: 8
Views: 67

### Re: sp^3

It seems to be common considering that when you use the octet rule to complete a lewis structure, there are always four bonds between the central atom and the surrounding atom. In this way, if we consider the electron arrangement of the molecule in terms of the central atom, we will always get four ...
Mon Nov 30, 2020 8:23 am
Forum: Biological Examples
Topic: vitamin b-12
Replies: 3
Views: 138

### Re: vitamin b-12

Vitamin b-12 does contain the metal cobalt, which is what forms an octahedral complex with five ligands four nitrogens from an amine group, and one ligand from a CH2 group. It acts as a catalyst (as a result of the weak bonds between the carbon in the CH2 and the cobalt) and it helps to prevent illn...
Mon Nov 30, 2020 8:19 am
Forum: Biological Examples
Topic: Hemoglobin
Replies: 12
Views: 226

### Re: Hemoglobin

The biological importance is that it binds to an oxygen ligand, specifically through five bonding points (4 nitrogen atoms binding points that also connect to a central iron atom and one histidine binding site which also is through another nitrogen atom) in this way a red blood cell can deliver oxyg...
Mon Nov 30, 2020 8:11 am
Forum: Biological Examples
Topic: Cisplatin Bonding
Replies: 4
Views: 25

### Re: Cisplatin Bonding

There have to be two guanines in a row to allows for a stronger bond to form between the cisplatin's two Cl atoms rather than have one bond form between them. Guanines have a special structure that allows them to bond to the ligand in that way. This GGCC pattern tends to be a common one in all biolo...
Tue Nov 24, 2020 10:12 am
Forum: Determining Molecular Shape (VSEPR)
Topic: regions of electron density
Replies: 7
Views: 60

### Re: regions of electron density

I wouldn't overthink it too much but I would think that the areas of electron density are where there are clusters of electrons (especially lone pairs). Double and Triple bonds are just another cluster of electrons so they are only considered one region of electron density which is similar to any ot...
Tue Nov 24, 2020 10:04 am
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pair e-
Replies: 3
Views: 37

### Re: lone pair e-

I don't think that lone pairs play a role in determining the polarity of a molecule directly. Like, having more lone pairs doesn't correlate to having more or less polarity. However, they DO influence the shape of the molecule and whether the dipole moments cancel out each other when there are polar...
Tue Nov 24, 2020 9:53 am
Forum: Hybridization
Topic: Lecture 23 question
Replies: 5
Views: 51

### Re: Lecture 23 question

The electrons that we count in Lewis structures directly translate into determining the shape of molecules and these electrons that we count are outer valence electrons. The 1s orbital isn't considered an outer shell and just forms the basis of how strong the ionization energy is compared to the siz...
Tue Nov 24, 2020 9:03 am
Forum: Sigma & Pi Bonds
Topic: Resonance and pi bonds
Replies: 3
Views: 47

### Re: Resonance and pi bonds

These are just my thoughts. Resonance structures, by definition, have a partial double bond character so all of the bond lengths are the same overall since they are a mixture or average of all the bond lengths of the lower energy Lewis structures. In this way, sigma and pi bonds wouldn't apply to th...
Tue Nov 24, 2020 8:50 am
Forum: Hybridization
Topic: 2F.1
Replies: 2
Views: 27

### Re: 2F.1

There isn't really the need to worry about the specifics but getting an understanding of the electron arrangement can aid in understanding the general orientation of the orbitals. The chart above is quite useful in this considering the orientation since the electron arrangements, or in order words, ...
Mon Nov 16, 2020 9:14 am
Forum: Coordinate Covalent Bonds
Topic: Lone Pairs and Lewis Bases
Replies: 4
Views: 46

### Re: Lone Pairs and Lewis Bases

In general, Lewis acids are electron-deficient and lone pairs on the central atom, especially excess ones if the central atom is a period 3 or greater element are a result of excess valence electrons so it's likely that the element is a base rather than an acid. Another kind of rule of thumb, Period...
Mon Nov 16, 2020 9:10 am
Forum: Dipole Moments
Topic: Strength of intermolecular forces
Replies: 3
Views: 46

### Re: Strength of intermolecular forces

Distance plays a huge role in determining the strength of dipole-dipole interactions since this increases the bond length between them making the interactions weaker (the measure of the interactions is divided by the distance cubed). If the dipole was interacting with an ion, however, there is a gre...
Mon Nov 16, 2020 9:01 am
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling Cl Oxidation Number
Replies: 2
Views: 22

### Re: Sapling Cl Oxidation Number

The oxidation number for the Chlorine is actually 7 considering that the sum of the oxidation numbers of each element adds up to the charge and oxygen has an oxidation number of -2. We have four oxygen as well so 4(-2)= 8 + _=-1. There has to be an oxidation number of 7 to make the charge -1. Since ...
Mon Nov 16, 2020 8:54 am
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 5
Views: 44

### Re: Bond Length

I've noticed that for bond length reference points it tends to vary based on the example you are looking at in terms of homework questions. There will usually be a table given to you of the experimental bond lengths compared to the actual bond lengths of the Lewis structure you are looking at. In th...
Mon Nov 16, 2020 8:48 am
Forum: Electronegativity
Topic: Homework Problem 3F.19
Replies: 4
Views: 25

### Re: Homework Problem 3F.19

a.) Xenon is larger than Argon in terms of the atomic radius so it's bound to have more LDF forces since a bigger electron cloud is easy to be distorted b.) There is more of a rod-like structure for diethyl along with its hydrogen bonds so it has more extensive LDF forces as well. C.) Again, the rod...
Mon Nov 09, 2020 8:27 am
Forum: Octet Exceptions
Topic: expanded octet in d orbital
Replies: 4
Views: 27

### Re: expanded octet in d orbital

So elements with an expanded orbital, meaning that they could potentially hold more electrons in a Lewis structure, has to do with the fact that the d-orbital allows for extra space of up to 10 valence electrons. Looking at the periodic table, we see that elements that are before Period 3 tend to ha...
Mon Nov 09, 2020 8:21 am
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating Formal Charge
Replies: 9
Views: 98

### Re: Calculating Formal Charge

Adding up the formal charges of the atoms of a molecule should give you the overall oxidation number if that's what you mean, but NOT the net formal charge. You will need to calculate the individual formal charges of each atom in order to understand if they have the correct configuration of electron...
Mon Nov 09, 2020 8:13 am
Forum: Ionic & Covalent Bonds
Topic: Electron Affinity
Replies: 8
Views: 65

### Re: Electron Affinity

Electron affinity is the measure of how much an element wants an electron. Elements that are the closest to becoming a noble gas have a high electron affinity since they want to complete their octet more than any of the other elements before it. It can be calculated by finding the difference between...
Mon Nov 09, 2020 8:07 am
Forum: Ionic & Covalent Bonds
Topic: Size of Bonds
Replies: 28
Views: 101

### Re: Size of Bonds

Double bonds are shorter considering that they are stronger bonds since the distance between the nuclei of two atoms is smaller. Single bonds are weaker than double bonds, considering the distance between their nuclei is larger. It takes more energy to break apart double bonds compared to single bon...
Mon Nov 09, 2020 8:04 am
Forum: Ionic & Covalent Bonds
Topic: Difference Between Ionic & Covalent Bonds
Replies: 11
Views: 63

### Re: Difference Between Ionic & Covalent Bonds

Ionic bonds are usually between elements that differ greatly in electronegativity or very opposite sides of the periodic table. Professor Lavelle told us that we would get a table with the electronegativity values so this could be helpful in determining something is an ionic bond. When it comes to L...
Mon Nov 02, 2020 7:59 am
Forum: Lewis Structures
Topic: Brackets for Anions
Replies: 6
Views: 46

### Re: Brackets for Anions

The brackets are used for other species, basically any ions like cations AND anions. This is the same in covalent and ionic bonding. If you end up starting off with two ions and covalently bond them, you will have brackets around the final Lewis structure since they maintain their charge. If you tra...
Mon Nov 02, 2020 7:54 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 11
Views: 347

### Re: Formal Charge

The charge would just be the result that you get directly from your equation, which is -1 in this case. Just because it's an electron doesn't make a difference since the equation only applies to electrons and with that reasoning and the equation, there is no way we will ALWAYS get a negative number.
Mon Nov 02, 2020 7:48 am
Forum: Electronegativity
Topic: Periodic Table Trend
Replies: 37
Views: 387

### Re: Periodic Table Trend

So the trend for ionization energy basically corresponds to the atomic radius of the element. The bigger the atomic radius, the lower the ionization energy. The atomic radii decrease along a period and increase down a group. SO we can say the ionization energy increases down a period and decreases d...
Mon Nov 02, 2020 7:39 am
Forum: Resonance Structures
Topic: Delocalization
Replies: 6
Views: 264

### Re: Delocalization

So, delocalization usually occurs with elements that have covalent bonds that can contribute to resonance. Certain lewis structures of the same compound or molecule are lower energy than others and we ideally want the lowest energy combination, which is explored with the concept of formal charge but...
Mon Nov 02, 2020 7:34 am
Forum: Ionic & Covalent Bonds
Topic: Differences in structures between ionic and covalent bonds
Replies: 7
Views: 72

### Re: Differences in structures between ionic and covalent bonds

The bonds are drawn the same way in terms of Lewis structures as the electron pairs are represented as dots. However, when you are drawing ionic bonds, the are no shared electrons represented but electrons are transferred from one "to be" cation to an anion that gains electrons. Both bonds...
Mon Oct 26, 2020 9:32 am
Forum: Empirical & Molecular Formulas
Topic: Dealing with Diatomic Elements
Replies: 11
Views: 116

### Re: Dealing with Diatomic Elements

For this question think about it in the context of the problem and that helped me a lot because I was struggling with the same thing. When you find the moles of each element you need to convert them in terms of one mole for the sake of the empirical formula you will write but the nitrogen produced f...
Mon Oct 26, 2020 9:20 am
Forum: Limiting Reactant Calculations
Topic: Excess reactant affecting limiting reactant
Replies: 7
Views: 78

### Re: Excess reactant affecting limiting reactant

Yes. It can be assumed that the oxygen is in excess means that the other reactant is what is limiting since all of it is being used up in the reaction rather than the reactant oxygen being not totally used up. For some of the questions we did, they just give you the weight of a single reactant, that...
Mon Oct 26, 2020 9:06 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Clarification on the "uncertainty" part of this equation
Replies: 7
Views: 112

### Re: Clarification on the "uncertainty" part of this equation

The uncertainty part comes from the fact the we don't know the change in velocity of the electron from area to another, because we know the time takes to travel from one distance to another but NOT the distance itself (velocity= distance/time). This is due to the fact that an electron is so small in...
Mon Oct 26, 2020 8:58 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2 orbitals occupied
Replies: 1
Views: 20

### Re: 2 orbitals occupied

I may not answer your question fully but this is what I am getting. You are on the right track in your thinking. These "orbitals" that you calculated from n=2 are correct. However, they refer to separate subshells which have their own number of orbitals of which the electrons (two per orbi...
Mon Oct 26, 2020 8:47 am
Forum: Quantum Numbers and The H-Atom
Topic: Spin Magnetic Quantum Number
Replies: 6
Views: 45

### Re: Spin Magnetic Quantum Number

For the spin magnetic quantum number, the +1/2 indicates up and the -1/2 indicates down. We were never taught how to actually calculate the spin, but there is some conceptual knowledge about how it was discovered in the first place which could guide your understanding. The Stern and Gerlach experime...
Mon Oct 26, 2020 8:40 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electrostatic Potential Energy
Replies: 1
Views: 16

### Re: Electrostatic Potential Energy

Electrostatic potential energy can just be thought as the amount of energy a particle retains relative to the outside forces it is facing. It is influenced by mainly two things: repulsion forces and attraction forces of the nucleus referred to as nuclear charge. Repulsion forces are between two elec...
Mon Oct 26, 2020 8:23 am
Forum: DeBroglie Equation
Topic: Circular Standing Waves around Atoms
Replies: 2
Views: 45

### Re: Circular Standing Waves around Atoms

Circular standing waves are just a model of how electrons can change their energy states in a oscillating fashion. Stable circular standing waves implies that the electron has enough energy, possibly from a photon, to make an energy change (delta E) that is equivalent to the energy change between n=...
Mon Oct 19, 2020 8:24 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 4
Views: 173

### Re: Orbitals

Finding the number of orbitals doesn't have a short cut to my knowledge, but it's not super hard to do. Know that l=0 is an s orbital, l=1 is a p, l=2 is a d orbital, and l=3 is an f-orbital. so, spdf. Btw, we get the l from the n or the shell number and l always is less than n. So for n=2 , for ins...
Mon Oct 19, 2020 8:10 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations that dont follow the pattern
Replies: 3
Views: 24

### Re: Electron Configurations that dont follow the pattern

So the elements that don't follow up the "building up principle" rules are: Mo, Cu, Cr, Ag, and Au. This is due to the fact that an electron from one of the orbitals moves to the other orbital to pair with its unpaired electron. If you were to do the electron configuration for Cu for insta...
Mon Oct 19, 2020 8:01 am
Forum: Photoelectric Effect
Topic: Atomic Specta Post-Module Assessment
Replies: 3
Views: 37

### Re: Atomic Specta Post-Module Assessment

You wouldn't need to use Avogadro's number, in this case, considering "Sodium atom" just refers to the electron being removed from something and not the number of atoms. Also, we use Avogadro's number to find the number of moles through division and the number of atoms through multiplicati...
Mon Oct 19, 2020 7:50 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Shape of Orbitals?
Replies: 6
Views: 178

### Re: Shape of Orbitals?

I'm pretty sure the whole orbital shape stuff is just to help with the conceptual understanding of the topic, you just have to understand the number of electrons in each orbital, the subshells, the principal quantum numbers, and electron spin. The shape of the orbital itself will not be asked about ...
Mon Oct 19, 2020 7:39 am
Forum: Einstein Equation
Topic: Sapling #5
Replies: 7
Views: 101

### Re: Sampling #5

At first glance, this is what I would do. I would use the wavelength in m (convert cm to using 10^-2) and then plug in just Planck's constant, the constant speed of light, and the wavelength given into the E=hC/wavelength equation. Once I get the number of Joules (E) of energy the photon can potenti...
Tue Oct 13, 2020 8:31 am
Forum: Empirical & Molecular Formulas
Topic: Empirical and Molecular Formulas
Replies: 9
Views: 132

### Re: Empirical and Molecular Formulas

I don't think the website meant the exact "same thing". You're right, the empirical formula is the relative number (ratio) of atoms per element and the molecular formula is the exact number of the atoms in the context of the actual balanced equation or experiment in a lab. However, they ar...
Tue Oct 13, 2020 8:22 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Problem E.15 [ENDORSED]
Replies: 3
Views: 98

### Re: Textbook Problem E.15[ENDORSED]

To put it simply, this problem is asking you to basically find a type of metal, add sulfur to that metal, and then find the molar mass of that metal and the sulfur. 1.) subtract the molar masses of hydrogen and oxygen from the total molar mass given. 2.) find an element on the periodic table that ha...
Tue Oct 13, 2020 8:15 am
Forum: SI Units, Unit Conversions
Replies: 12
Views: 106

Avogadro's number represents the number of atoms/formula units/molecules in a mole. So it can be denoted as 6.002 * 10^23 atoms/mole. You can use Avogadro's number to find the number of atoms of something in a mole form, essentially converting moles to atoms. Note: every element has the same number ...
Tue Oct 13, 2020 8:10 am
Forum: Photoelectric Effect
Topic: Photoelectric Effect original purpose
Replies: 6
Views: 32

### Re: Photoelectric Effect original purpose

The main question that fueled the set up of the "photoelectric experiment" was to answer the questions how "how different were the work functions or as they called it "threshold potentials" between the different elements?". To answer these questions, metal plates were t...
Tue Oct 13, 2020 7:55 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: How to know whether answer is in mols or atoms
Replies: 5
Views: 96

### Re: How to know whether answer is in mols or atoms

Firstly, the "amount" always refers to the moles of something, so you know your answer will not have to be multiplied by Avogadro's number to cancel out the moles for atoms/molecules/formula units which are the same things by the way. The amount never refers to atoms so multiplying moles t...
Mon Oct 05, 2020 5:49 pm
Forum: Balancing Chemical Reactions
Topic: Reaction Terminology "In excess"
Replies: 11
Views: 129

### Re: Reaction Terminology "In excess"

If it states "in excess" it refers to the fact that one of the reactants is not the limiting reactant so in excess DOES refer to the reactant. I notice it's common to have a problem analyzing the limiting reactants or anything related to the reactants with combustion reactions.
Mon Oct 05, 2020 5:33 pm
Forum: Balancing Chemical Reactions
Topic: Hmk. Problem H.11 (Fundamentals)
Replies: 5
Views: 55

### Re: Hmk. Problem H.11 (Fundamentals)

So the way I approached this problem is based on first getting the big picture of O atoms. To balance the O atoms, you have to first realize that the number of O atoms on the product side can only be even(CO2), where as the number of O atoms on the reactant side can be either odd or even(Fe3O4 and ...
Mon Oct 05, 2020 4:44 pm
Forum: Balancing Chemical Reactions
Topic: Hmk. Problem H.11 (Fundamentals)
Replies: 5
Views: 55

### Hmk. Problem H.11 (Fundamentals)

Question: In one stage in the commercial production of iron metal in a blast furnace, the iron(III) oxide, Fe 2 O 3 , reacts with carbon monoxide to form solid Fe 3 O 4 and carbon dioxide gas. In a second stage, the Fe 3 O 4 reacts further with carbon monoxide to produce solid elemental iron and car...
Mon Oct 05, 2020 4:28 pm
Forum: Balancing Chemical Reactions
Topic: Hmk. Problem H.3 (Fundamentals)
Replies: 6
Views: 53

### Hmk. Problem H.3 (Fundamentals)

Question: The first box below represents the reactants for a chemical reaction and the second box the products that form if all the reactant molecules shown react. Use the following key to write a balanced equation for the reaction. Assume that if two atoms are touching, they are bonded together. Ke...