Search found 78 matches

by Meredithe DeGuzman4G
Sun Feb 09, 2020 9:11 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed system
Replies: 7
Views: 18

Re: closed system

It’s sealed so no matter can leave or come in. But since it’s not insulated, heat can still be exchanged. So it is a closed system.
by Meredithe DeGuzman4G
Sun Feb 09, 2020 9:08 pm
Forum: Phase Changes & Related Calculations
Topic: heat added/released
Replies: 6
Views: 26

Re: heat added/released

Forming new bonds releases energy. In a synthesis reaction where you’re forming a new product from its reactants, energy will be released because the new product is more stable. Breaking bonds requires energy. In decomposition reactions where you’re breaking apart a molecule into its simpler parts, ...
by Meredithe DeGuzman4G
Sun Feb 09, 2020 9:03 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 65
Views: 2226

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

Why is delta H always q but q is not always delta H? What exactly does he mean by that? The definition of enthalpy is energy/heat absorbed or released at constant pressure (state function). So delta H is always q. Heat only describes energy transfer due to a temperature difference. Heat can be exch...
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:58 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed System
Replies: 7
Views: 40

Re: Closed System

DHavo_1E wrote:Hello,

Could I ask whether anyone could give an example of a closed system? Thank you!


Hi, an example of a closed system is a closed beaker. matter can't enter or leave the system, but the beaker isn't insulated to heat can still be exchanged. Hope this helps!
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:53 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Double bonds
Replies: 4
Views: 20

Re: Double bonds

I'm not sure if this is the answer you're looking for, but you can't break one bond of a double bond. You have to break the whole thing and reform it as a single bond. You'll have different bond enthalpies for the same atoms bonded with a single bond versus a double bond.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:50 am
Forum: Calculating Work of Expansion
Topic: temperature
Replies: 7
Views: 23

Re: temperature

It's because you're measuring the change in units. It doesn't really matter whether you're using one unit or another. There is no difference between going up 1 unit of kelvin and going up 1 unit of Celsius because the change is still one unit.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:44 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneous vs. Energetically Favorable
Replies: 3
Views: 7

Re: Spontaneous vs. Energetically Favorable

Nick Lewis 4F wrote:So all energetically favorable reactions are spontaneous but not all spontaneous reactions are energetically favorable?


Yes. Energetically favorable reactions don't require energy input so they are exothermic reactions. But not all exothermic reactions occur spontaneously.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:37 am
Forum: Calculating Work of Expansion
Topic: Intergral
Replies: 6
Views: 21

Re: Intergral

It's because the integral calculates the area under the curve. In the pressure v volume graph, calculating the area under the curve will give you the amount of work done to the surroundings.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:36 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Piston Example
Replies: 3
Views: 7

Re: Piston Example

In expansion work, the work done to the surroundings is the energy lost to push against the external pressure. This is one way you can change the energy of the system.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:32 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Types of Systems
Replies: 7
Views: 25

Re: Types of Systems

VLi_2B wrote:Can someone please give an example of an isolated system that is not a bomb calorimeter or a hydroflask?


The universe since energy is conserved.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:28 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated?
Replies: 7
Views: 21

Re: closed vs isolated?

A closed beaker is an example of a Closed system. Matter can't leave/enter but the beaker isn't insulated so heat can still be transferred.

The bomb calorimeter is an example of an isolated system. No heat or matter can be exchanged.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:26 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Specific heat capacity
Replies: 7
Views: 19

Re: Specific heat capacity

Molar heat capacity deals with 1 mole so it will use moles. Specific heat deals with 1 gram of a substance so it will use grams in its units.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:24 am
Forum: Calculating Work of Expansion
Topic: Reversible
Replies: 7
Views: 14

Re: Reversible

^^ What he said. If it's at equilibrium, it's reversible because it's done in infinitesimally small amounts.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:22 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: enthalpy
Replies: 7
Views: 27

Re: enthalpy

At constant pressure, enthalpy is the amount of heat released or absorbed by the reaction.
by Meredithe DeGuzman4G
Mon Feb 03, 2020 12:19 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy and Internal Energy
Replies: 2
Views: 12

Re: Enthalpy and Internal Energy

Enthalpy doesn't have to be at constant pressure. It's just that at constant pressure, enthalpy will just be the heat released or absorbed by the reaction. All of the work will be done will be to change the volume of the system. We just use constant pressure to relate heat to enthalpy. Most reaction...
by Meredithe DeGuzman4G
Sun Feb 02, 2020 11:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: state functions
Replies: 10
Views: 29

Re: state functions

State functions don't depend on the "path" they take. Usually they'll usually just involve the intial and final states. Some examples are enthalpy, temperature, density, volume, and pressure. Nonexamples have many parameters/variables in their equations because we have to consider them whe...
by Meredithe DeGuzman4G
Sun Feb 02, 2020 11:50 pm
Forum: Calculating Work of Expansion
Topic: Area under the curve
Replies: 3
Views: 18

Re: Area under the curve

It's because on a pressure vs volume graph, calculating the area under the curve gives you the amount of work done to the surroundings. For reversible expansions, this is the entire area under the curve from V1 to V2. For irreversible expansions, it's gonna be the rectangle formed from V1 to V2 at t...
by Meredithe DeGuzman4G
Sun Feb 02, 2020 11:46 pm
Forum: Phase Changes & Related Calculations
Topic: intensive/extensive
Replies: 4
Views: 16

Re: intensive/extensive

Intensive properties don't depend on how much material you have in the system. Some examples are temperature, density, molar heat capacity, and pressure. Extensive properties do depend on how much material you have in the system. Examples are volume, mass, enthalpy, entropy, heat capacity, and inter...
by Meredithe DeGuzman4G
Sun Jan 26, 2020 9:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Weak acid/base
Replies: 14
Views: 42

Re: Weak acid/base

Lavelle says to memorize all the strong acids and bases so that anything else you see, you immediately know is weak. Also, as someone mentioned above, having ka or kb as a given means you have a weak acid or base. Remember that strong acids and bases completely disassociate, giving an infinity disas...
by Meredithe DeGuzman4G
Sun Jan 26, 2020 9:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: protonization/ionization
Replies: 4
Views: 20

Re: protonization/ionization

its the conjugate base/original acid or conjugate acid/original base. What it's really comparing is the original acid/base you started with and how many of those gained/lost a proton to become its conjugate. The formula gives you a ratio/percent
by Meredithe DeGuzman4G
Sun Jan 26, 2020 9:36 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Shifts Left or Right
Replies: 15
Views: 42

Re: Reaction Shifts Left or Right

In this scenario, I think of heat as a product. This will make sense as to why it shifts left. On the molecular level, heat is added to the products side of the equation so when heat goes up it increases the number of collisions of products to become reactants.
by Meredithe DeGuzman4G
Sun Jan 26, 2020 9:31 pm
Forum: Phase Changes & Related Calculations
Topic: Heat v Enthalpy
Replies: 3
Views: 20

Re: Heat v Enthalpy

What helps me is to look at the formula of heat and enthalpy. Enthalpy can be calculated using the initial and finals states. Heat is calculated using a bunch of parameters meaning it depends on the path taken.
by Meredithe DeGuzman4G
Sun Jan 26, 2020 9:13 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Meaning of State Function
Replies: 8
Views: 22

Re: Meaning of State Function

Enthalpy is a state function because it does not depend on the path taken, only the initial and final values matter.
by Meredithe DeGuzman4G
Sun Jan 19, 2020 11:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: identifying acids & bases
Replies: 5
Views: 20

Re: identifying acids & bases

You should familiarize yourself with the strong acids and strong bases. There's a list online and videos on youtube to help you memorize. Like what people said, you could also look for acids and bases using the Lewis and Bronsted-Lowry definitions. But I think to prepare for the test, knowing that l...
by Meredithe DeGuzman4G
Sun Jan 19, 2020 11:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for Gases
Replies: 12
Views: 62

Re: K for Gases

Kp is the specific notation used for gases or when given partial pressures.
by Meredithe DeGuzman4G
Sun Jan 19, 2020 11:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: reaction quotient
Replies: 4
Views: 11

Re: reaction quotient

if you calculate q and it equals k then it is at equilibrium. If they don't equal, then it's not and the reaction is still occurring. From there you can compare q and k to determine which way the reaction will proceed to reach equilibrium.
by Meredithe DeGuzman4G
Sun Jan 19, 2020 11:16 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: lewis structure
Replies: 11
Views: 32

Re: lewis structure

No lavelle just does to build on 14a material and for visualization, but on the test you won't get extra points for it. You could anyway if it helps to understand the chemistry
by Meredithe DeGuzman4G
Sun Jan 19, 2020 11:15 pm
Forum: Ideal Gases
Topic: Using PV=nRT
Replies: 7
Views: 28

Re: Using PV=nRT

If it does, it will be in the context of converting partial pressure to concentration or vice versa
by Meredithe DeGuzman4G
Mon Dec 09, 2019 12:52 am
Forum: Naming
Topic: "Ferrate"
Replies: 14
Views: 137

Re: "Ferrate"

Ferrate follows the rule of naming anions with adding -ate at the end, but use the latin name for Iron just cause it sounds better.
by Meredithe DeGuzman4G
Mon Dec 09, 2019 12:50 am
Forum: Hybridization
Topic: Identifying Hybrid Orbitals
Replies: 5
Views: 34

Re: Identifying Hybrid Orbitals

I just count the electron density regions from s, p2, p3, d, d2, d3. Rarely if ever do I go higher than that.
by Meredithe DeGuzman4G
Mon Dec 09, 2019 12:47 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Nitro vs Nitrito
Replies: 6
Views: 46

Re: Nitro vs Nitrito

I believe he wants us to use Nitro for NO2 and nitrito for ONO
by Meredithe DeGuzman4G
Thu Dec 05, 2019 7:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Emission Spectrum of Hydrogen
Replies: 1
Views: 32

Emission Spectrum of Hydrogen

When would we get positive values when using -hR/n^2? Or is it always negative? Does emission/absorption change the sign?
by Meredithe DeGuzman4G
Thu Dec 05, 2019 7:12 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in Position
Replies: 1
Views: 32

Uncertainty in Position

When we are given the value for the uncertainty in position, when do I multiply it by 2? Sometimes the solution will require double the uncertainty given and other times it's not.
by Meredithe DeGuzman4G
Sun Dec 01, 2019 8:05 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH of bases
Replies: 3
Views: 27

Re: Calculating pH of bases

TO find ph, take the negative log of the base concentration (pOH) then subtract that amount from 14 to give you pH.
by Meredithe DeGuzman4G
Sun Dec 01, 2019 7:59 pm
Forum: Dipole Moments
Topic: dipole moments
Replies: 6
Views: 43

Re: dipole moments

Yes. If you draw a Lewis structure with a dipole it is polar. Sometimes, a molecule will have dipole movements but cancel each other out. In this case, the molecular is going to be non polar.
by Meredithe DeGuzman4G
Sun Dec 01, 2019 7:52 pm
Forum: SI Units, Unit Conversions
Topic: midterm/final
Replies: 18
Views: 246

Re: midterm/final

I think it’s going to be more calculation heavy based on the midterm mixed with conceptual questions so I wouldn’t neglect studying them.
by Meredithe DeGuzman4G
Sun Dec 01, 2019 7:40 pm
Forum: Hybridization
Topic: Writing the hydrization
Replies: 10
Views: 86

Re: Writing the hydrization

Hello, I have a question about the difference between 2sp3 and sp3. How do you know if the "2" in front of the sp3 is supposed to be there? What's the difference between the two? It’s the quantum number of the central atom when you’re talking about the hybridization of a molecule. Describ...
by Meredithe DeGuzman4G
Sun Dec 01, 2019 7:35 pm
Forum: Lewis Structures
Topic: Bent or Angular?
Replies: 15
Views: 95

Re: Bent or Angular?

Both bent and angular refer to the same shape
by Meredithe DeGuzman4G
Sun Nov 24, 2019 9:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Intermolecular forces
Replies: 5
Views: 30

Re: Intermolecular forces

Hydrogen bonding: H bonded to FON with a LP. Only H bonded to FON will be attracted to other regions with H bonded to FON Ions can have: ion-dipole, ion-ion anything with dipole moments will have: dipole-dipole molecule w dipole + molecule w no dipole = dipole-induced-dipole All Molecules (polar and...
by Meredithe DeGuzman4G
Sun Nov 24, 2019 9:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 3
Views: 30

Re: Polarity

I don't know if big molecules are going to be tested, but it'd only be helpful to know how to draw any lewis structure and determine polarity.
by Meredithe DeGuzman4G
Sun Nov 24, 2019 9:15 pm
Forum: Hybridization
Topic: d orbital
Replies: 4
Views: 29

Re: d orbital

it's because d is a lower energy state than p or s. When we do electron configuration, it's why we do n-1 when passing thru the transition metals/d block.
by Meredithe DeGuzman4G
Sun Nov 24, 2019 9:14 pm
Forum: Biological Examples
Topic: Biological Examples
Replies: 10
Views: 56

Re: Biological Examples

I noticed he likes to use those as examples in questions he gives out. I would study concepts around these examples since they seem to be fair game.
by Meredithe DeGuzman4G
Sun Nov 24, 2019 9:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shape
Replies: 3
Views: 24

Re: T Shape

Yes, T shape has 5 bonding regions giving it bipyramidal geometry. And 2 Lone pairs that push/repel the 3 bonding regions into a T shape.
by Meredithe DeGuzman4G
Sun Nov 17, 2019 8:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Radicals
Replies: 5
Views: 35

Re: Radicals

I thought CH3 would be trigonal pyramidal because of its tetrahedral geometry and 1 LP bonding region but it's trigonal planar.
by Meredithe DeGuzman4G
Sun Nov 17, 2019 8:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Influence of Lone Pair e- on Model
Replies: 5
Views: 39

Re: Influence of Lone Pair e- on Model

Greater. A lone pair will increase e- repulsion, causing the bond angles to be slightly smaller than if there was an atom in place.
by Meredithe DeGuzman4G
Sun Nov 17, 2019 8:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear molecule with lone pairs
Replies: 3
Views: 24

Re: Linear molecule with lone pairs

A linear molecule can have 3 lone pairs with a geometry of trigonal pyramidal (5 bonding regions). The lone pairs will push the bonds into a linear shape. Same thing with 4 lone pairs with a geometry of an octahedral. The 2 bonding regions will be farthest apart in a linear shape.
by Meredithe DeGuzman4G
Sun Nov 17, 2019 6:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 5
Views: 28

Re: Lone Pairs

Bent = 1 or 2 LPs
trigonal pyramidal = 1 LP
linear = when 3 or 4 LPs
See-saw = 1 LP
T shaped = 2 LPs
Square planar = 1 LP
Square pyramidal = 2 LP
by Meredithe DeGuzman4G
Sun Nov 10, 2019 11:02 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bond Strength
Replies: 8
Views: 55

Re: Hydrogen Bond Strength

ShreyaKannan1B wrote:Which elements does hydrogen form hydrogen bonds with?



FON - Fluorine, oxygen, and nitrogen
by Meredithe DeGuzman4G
Sun Nov 10, 2019 10:53 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths and strength
Replies: 4
Views: 20

Re: Bond lengths and strength

It's because they're shorter that makes them stronger. More shared electrons create a stronger bond because more electrons are present that can pull on the nuclei which means the atoms get even closer and stronger bond forms.
by Meredithe DeGuzman4G
Sun Nov 10, 2019 10:48 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Viscosity
Replies: 15
Views: 101

Re: Viscosity

I like to think of viscosity as how easily a liquid flows. Something that has high vicosity, like molasses, has strong intermolecular forces. Something with high viscosity is also described as being really thick, like molasses. Water has lower viscosity and flows much easier than molasses because it...
by Meredithe DeGuzman4G
Sun Nov 10, 2019 10:43 pm
Forum: Dipole Moments
Topic: dipole moments
Replies: 2
Views: 19

Re: dipole moments

Dipole moments exist because electrons move in a cloud. Electrons occupy one side over another at random times, producing a temporary separation of charge. Molecules with no charges still experience attraction on the intermolecular level because of these temporary dipoles. The tendency of electrons ...
by Meredithe DeGuzman4G
Fri Nov 01, 2019 2:11 am
Forum: Bond Lengths & Energies
Topic: Lattice Energy
Replies: 9
Views: 41

Re: Lattice Energy

Ionic bonds form crystalline lattices in their solid form. Forming bonds releases energy (they become more stable). If a molecule has ionic bonds (cation and anion) and is in the gas phase, the amount of energy released as it condenses into a solid is called lattice energy.
by Meredithe DeGuzman4G
Fri Nov 01, 2019 2:07 am
Forum: Electronegativity
Topic: electronegative
Replies: 6
Views: 33

Re: electronegative

It depends. If the difference is really big, the atom w the higher electronegativity will literally "pull" electron(s) from the other atom. The result is a cation and anion, and an ionic bond forms because of electrostatic forces between opposite charges (another way of saying opposites at...
by Meredithe DeGuzman4G
Fri Nov 01, 2019 1:58 am
Forum: Ionic & Covalent Bonds
Topic: Valence Electrons?
Replies: 15
Views: 103

Re: Valence Electrons?

I just count across the period. For transition metals, if they ask, go off the number of electrons in the highest principle quantum number. If they ask for the d block electrons, then add those in too. Problem 2A1 letter c is an example. Mn is said to have 7 VE - 2 from 4p2 and 5 from 3d5
by Meredithe DeGuzman4G
Fri Nov 01, 2019 1:55 am
Forum: Ionic & Covalent Bonds
Topic: Electrostatic Potential Energy
Replies: 3
Views: 26

Re: Electrostatic Potential Energy

I dont think so either. But it would be good to know that the formula just says that as the radius gets bigger, the electrostatic/Coulomb's force decreases.
by Meredithe DeGuzman4G
Thu Oct 31, 2019 9:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Relationship between uncertainties of position and momentum
Replies: 2
Views: 19

Re: Relationship between uncertainties of position and momentum

Heisenberg's uncertainty principle is different from Bohr's (classical) model. Bohr's model assumes that electrons are orbitting an electron and that is not the case. Electrons are really moving in a "cloud". So if you wanna know its position, that means you have to stop the electron so yo...
by Meredithe DeGuzman4G
Fri Oct 25, 2019 12:45 am
Forum: Properties of Light
Topic: photoelectric effect
Replies: 4
Views: 41

Re: photoelectric effect

I like to think of light intensity a how strong a light shines - the number of photons a light emits. If it changed frequency, i'd see a different color light. But Einstein's experiment shows that's what you need to do to knock off more electrons because colors with higher frequencies (lower wavelen...
by Meredithe DeGuzman4G
Fri Oct 25, 2019 12:36 am
Forum: Ionic & Covalent Bonds
Topic: Resonance
Replies: 12
Views: 94

Re: Resonance

When molecules have resonance their e- exist in a hybrid of their lewis structures. Their e- can make those bonds (delocalized) to lower their repulsion. The result is a more stable atom. A molecule with more Lewis structures is more stable.
by Meredithe DeGuzman4G
Fri Oct 25, 2019 12:21 am
Forum: Ionic & Covalent Bonds
Topic: Isoelectronic Atoms
Replies: 6
Views: 54

Re: Isoelectronic Atoms

It's valence electrons. They could ask you for isoelectronic atoms (like as anions or cations) given a periodic table but idk
by Meredithe DeGuzman4G
Fri Oct 25, 2019 12:13 am
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 4
Views: 53

Re: Resonance Structures

The Lewis structure isn't perfect & sometimes we're able to draw many Lewis structures for a molecule. This is called resonance. In this case, the molecule actually exists as a hybrid of all its resonance structures. And probably not, and he's said that he'll accept any correct structure.
by Meredithe DeGuzman4G
Fri Oct 18, 2019 2:14 am
Forum: Photoelectric Effect
Topic: E = pc
Replies: 3
Views: 38

Re: E = pc

E=pc is especially helpful to find the momentum of light which does not have rest mass (so you can't use p=mv). Light has no rest mass but does have momentum in the form of energy.
by Meredithe DeGuzman4G
Fri Oct 18, 2019 2:12 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configurations
Replies: 3
Views: 28

Re: electron configurations

We remove electrons from the highest energy subshell because these electrons are the most unstable and the atom will readily give them up to become more stable.
by Meredithe DeGuzman4G
Fri Oct 18, 2019 2:05 am
Forum: Properties of Electrons
Topic: Wave Function
Replies: 5
Views: 75

Re: Wave Function

We use the wave function to find the probability of where an electron is going to be. As we get down to the very small, light acts more like a wave. The wave function helps us model the location of the electrons and determines which orbitals are going to be present.
by Meredithe DeGuzman4G
Fri Oct 18, 2019 1:56 am
Forum: Properties of Light
Topic: How does light have momentum but we assume it has no mass?
Replies: 4
Views: 38

Re: How does light have momentum but we assume it has no mass?

Light doesn't have rest mass at least. So we can't really use the mv equation. But it does have momentum in the form of energy. We can use another equation instead to find its momentum, E=pc where E is the energy of the photon, and c is the speed of light.
by Meredithe DeGuzman4G
Fri Oct 18, 2019 1:38 am
Forum: Properties of Light
Topic: Unit for Wavelength
Replies: 34
Views: 164

Re: Unit for Wavelength

wavelength is just measuring one peak to the next so this distance is in meters
by Meredithe DeGuzman4G
Fri Oct 18, 2019 1:36 am
Forum: Properties of Light
Topic: Unit Conversions
Replies: 6
Views: 61

Re: Unit Conversions

This is my method: I put the units that i have on the bottom, and the units i want on top. I put a 1 next to the bigger units. Then for the smaller units, I subtract the scientific notations of the bigger unit from the smaller unit. Then I multiply these factors. Ex: 18.2 nm in cm? 18.2 x 1 cm/10^7 ...
by Meredithe DeGuzman4G
Thu Oct 10, 2019 8:31 pm
Forum: Properties of Electrons
Topic: Energy of Electron
Replies: 10
Views: 104

Re: Energy of Electron

when you say energy is quantized, this means energy can only be absorbed or emitted in specific (discrete) amounts. This means at some point, you can't divide energy into smaller amounts.
by Meredithe DeGuzman4G
Thu Oct 10, 2019 8:29 pm
Forum: Significant Figures
Topic: How many significant figures are in 7.00 x 10^2?
Replies: 12
Views: 150

Re: How many significant figures are in 7.00 x 10^2?

7.00 x 10^3 has three sig figs because when there is a decimal, all the zeroes are significant (including those inbetween integers and after them). 700 is another way of saying the same thing, but only has 1 sig fig because when there are no decimals, only 0s in between numbers are significant, not ...
by Meredithe DeGuzman4G
Thu Oct 10, 2019 8:25 pm
Forum: Properties of Light
Topic: "Work Function" (from Post-Assessment Module)
Replies: 4
Views: 47

Re: "Work Function" (from Post-Assessment Module)

In the context of the photoelectric effect and experiment, the work functions describe the minimum energy a photon needs to knock off an electron so that the electron can overcome it's an attraction to the plate. Some electrons are more attracted to the metal than others. Those with the highest max ...
by Meredithe DeGuzman4G
Thu Oct 10, 2019 8:15 pm
Forum: Photoelectric Effect
Topic: How the Photoelectric Effect Proves Light is a Photon
Replies: 4
Views: 65

Re: How the Photoelectric Effect Proves Light is a Photon

In the experiment, if light acts only as a wave then increasing the intensity should increase the number of electrons ejected from the plate and increase their maximum kinetic energy. The wave theory would also predict that changing the frequency has no effect at all. Particle theory says just the o...
by Meredithe DeGuzman4G
Thu Oct 10, 2019 8:01 pm
Forum: Significant Figures
Topic: Sig Figs on Tests
Replies: 24
Views: 276

Re: Sig Figs on Tests

as a general rule, if they give you a bunch of given numbers you should use the value with the least number of significant figures to write your answer.
by Meredithe DeGuzman4G
Fri Oct 04, 2019 12:15 am
Forum: Balancing Chemical Reactions
Topic: H11
Replies: 3
Views: 39

Re: H11

1) 3Fe2O3 + CO = 2Fe3O4 + CO2
2) Fe3O4 + 4CO = 3Fe + 4CO2
by Meredithe DeGuzman4G
Fri Oct 04, 2019 12:12 am
Forum: Balancing Chemical Reactions
Topic: Differentiating between elements are molecules or single
Replies: 4
Views: 66

Re: Differentiating between elements are molecules or single

Two atoms of oxygen is a gas at room temperature. It's a diatomic element because it exists as two atoms together. There are 7 elements total in the periodic table that are diatomic elements. They are all gases at room temperature. Hydrogen (H2) Nitrogen (N2) Oxygen (O2) Fluorine (F2) Chlorine (Cl2)...
by Meredithe DeGuzman4G
Fri Oct 04, 2019 12:01 am
Forum: Limiting Reactant Calculations
Topic: Percent or theoretical yield
Replies: 14
Views: 149

Re: Percent or theoretical yield

the theoretical yield is what you calculate using the limiting reactant. but there are impurities and side reactions, and the percent yield tells you the ratio of the actual amount you get. theoretical yield is the best case scenario.
by Meredithe DeGuzman4G
Thu Oct 03, 2019 4:43 pm
Forum: SI Units, Unit Conversions
Topic: E.1 7th edition
Replies: 4
Views: 40

Re: E.1 7th edition

Calculate the number of atoms in 1 mol Ag using Avagadro's number 1 mol Ag * (6.022*10^23 atoms Ag/1 mol Ag)= 6.022*10^23 Ag atoms calculate the diameter of each atom where 2r=d 144ppm*2= 288ppm multiply the diameter of each atom by the number of atoms to get the total length then convert to meters ...
by Meredithe DeGuzman4G
Thu Oct 03, 2019 4:27 pm
Forum: Molarity, Solutions, Dilutions
Topic: Fundamentals F: The Determination of Composition Question #9
Replies: 3
Views: 43

Re: Fundamentals F: The Determination of Composition Question #9

Assume a 100g sample which gives 63.15g of C, 5.3g of H, and 31.55g of O. Convert to moles by dividing each sample mass by their molar masses. Once you have each of their moles, divide by the smallest and multiply by 3 to get the empirical formula in whole numbers

C8H8O3

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