Search found 45 matches

by yuetao4k
Sun Feb 10, 2019 9:47 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Open vs Closed System
Replies: 13
Views: 65

Re: Open vs Closed System

Closed systems have a barrier that prevents matter from escaping. Open systems have no form of barrier that prevents anything from being transferred to the surrounding.
by yuetao4k
Sun Feb 10, 2019 9:42 pm
Forum: Phase Changes & Related Calculations
Topic: Celsius and Kelvin
Replies: 6
Views: 19

Re: Celsius and Kelvin

You don't need to convert it when you're only using the difference in the temperatures in your equation because the differences will be the same. You need to convert when you're using a specific temperature (not the change) and when you are trying to find a ratio between initial and final temperatur...
by yuetao4k
Thu Jan 31, 2019 6:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Symbol
Replies: 5
Views: 33

Re: Enthalpy Symbol

The naught symbol indicates that the conditions are standard.
by yuetao4k
Thu Jan 31, 2019 6:47 pm
Forum: Phase Changes & Related Calculations
Topic: What Does U and q stand for?
Replies: 9
Views: 60

Re: What Does U and q stand for?

delta U is internal energy and q is the heat.
by yuetao4k
Thu Jan 31, 2019 6:46 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 14
Views: 80

Re: closed vs isolated

Energy can be exchanged with the surroundings. Nothing can be exchanged in an isolated system.
by yuetao4k
Sat Jan 26, 2019 8:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: method 1
Replies: 4
Views: 24

Re: method 1

Yes, one of the points of adding the equations together is to cancel out compounds that are not needed.
by yuetao4k
Sat Jan 26, 2019 8:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 5
Views: 20

Re: Hess's Law

Yes, make sure that all states of matter can cancel out and then manipulate each equation (multiplying or flipping) so that you get the final equation. Add together the enthalpies to find the enthalpy of the reaction.
by yuetao4k
Sat Jan 26, 2019 8:29 pm
Forum: Ideal Gases
Topic: OH and H3O
Replies: 9
Views: 71

Re: OH and H3O

You can calculate pH and pOH from [H30+] and [OH-] respectively by taking the negative log of the concentrations. This will indicate if the chemical compound is an acid or base.
by yuetao4k
Mon Jan 21, 2019 10:57 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Percent Protonation
Replies: 6
Views: 27

Re: Percent Protonation

It is calculated by dividing the concentration of the conjugate acid by the concentration of the initial base and multiplying that by 100.
by yuetao4k
Mon Jan 21, 2019 10:53 pm
Forum: Ideal Gases
Topic: ICE table
Replies: 10
Views: 55

Re: ICE table

It can be used for both!
by yuetao4k
Mon Jan 21, 2019 10:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: how to determine if something is an acid or base
Replies: 4
Views: 22

Re: how to determine if something is an acid or base

There is a list of common acids/bases that you could take a look at which could help you determine if a compound is an acid or base. You can also look at the pH if it is given, and that is a clear indicator of which one it is.
by yuetao4k
Thu Jan 17, 2019 1:17 pm
Forum: Ideal Gases
Topic: Water
Replies: 9
Views: 69

Re: Water

Water can be a solid liquid or gas, but not aqueous.
by yuetao4k
Thu Jan 17, 2019 1:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q vs K [ENDORSED]
Replies: 4
Views: 46

Re: Q vs K [ENDORSED]

Q can be calculated at any given point of the reaction. K is calculated when the system is in equilibrium.
by yuetao4k
Thu Jan 17, 2019 1:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables [ENDORSED]
Replies: 11
Views: 51

Re: ICE Tables [ENDORSED]

You will be given this information from the question.
by yuetao4k
Sat Dec 08, 2018 5:20 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 3573

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Thank you for the churro review! I also really liked garlic bread(:
by yuetao4k
Sun Dec 02, 2018 11:36 pm
Forum: Naming
Topic: Roman Numeral
Replies: 5
Views: 61

Re: Roman Numeral

The roman numerals correlate with the transition metal's oxidation number. Ag, Fe, Cu, and Pb are some examples of elements that need a roman numeral when naming them.
by yuetao4k
Sun Dec 02, 2018 11:17 pm
Forum: Naming
Topic: Naming
Replies: 5
Views: 89

Re: Naming

OH2 and H2O are used depending on which element is doing the bonding. Two elements that bind together will be written right next to each other.
by yuetao4k
Sun Dec 02, 2018 11:15 pm
Forum: Naming
Topic: Naming Question
Replies: 5
Views: 40

Re: Naming Question

OH2 has a charge of zero. Cl has a charge of 1-, so that means Fe has a charge of 2+ because the overall charge of the compound is 1+.
by yuetao4k
Sun Nov 25, 2018 10:12 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 13
Views: 91

Re: Speed of light

Use the given constants until the end of the problem and then round to your significant figures!
by yuetao4k
Sun Nov 25, 2018 10:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming
Replies: 5
Views: 35

Re: Naming

Yes, the molecular geometry and electron arrangements would be the same if there are no lone pairs.
by yuetao4k
Sun Nov 25, 2018 10:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Naming the Shape
Replies: 16
Views: 121

Re: Naming the Shape

There are charts that are organised in a specific way that can help with memorizing. You can google molecular shapes and be able to find a chart!
by yuetao4k
Sun Nov 25, 2018 10:03 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 2
Views: 330

Re: Electronegativity

The periodic table that is provided is always the same, so you can refer to the past periodic tables that have been provided.
by yuetao4k
Sun Nov 25, 2018 10:00 pm
Forum: Sigma & Pi Bonds
Topic: Double Bonds
Replies: 9
Views: 79

Re: Double Bonds

Double bonds have a sigma and a pi bond!
by yuetao4k
Sun Nov 25, 2018 9:59 pm
Forum: Electronegativity
Topic: Radius
Replies: 6
Views: 65

Re: Radius

As electronegativity increases, the pull on the electrons is greater. This means that the electrons are closer to the nucleus, thus giving the molecule a smaller atomic radius.
by yuetao4k
Sun Nov 18, 2018 8:21 pm
Forum: Bond Lengths & Energies
Topic: Strength of Bonds
Replies: 9
Views: 109

Re: Strength of Bonds

The stronger the bond, the higher the melting/boiling point.
by yuetao4k
Sun Nov 18, 2018 12:44 pm
Forum: Bond Lengths & Energies
Topic: Bond Length and Resonance
Replies: 5
Views: 74

Re: Bond Length and Resonance

Bond lengths are the same. Resonance structures give different locations for the different types of bonds, but lengths of the bonds are the same.
by yuetao4k
Sun Nov 18, 2018 12:42 pm
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 4
Views: 60

Re: Bond Lengths

In nature, the bond lengths are going to be the same for double and triple and single bonds in a molecule.
by yuetao4k
Mon Nov 12, 2018 12:17 am
Forum: Bond Lengths & Energies
Topic: Determine bond length
Replies: 3
Views: 53

Re: Determine bond length

You would need to know the different bond lengths to gauge how long a bond length would be in relation to the given length. In other words, you need to be given at least one bond length in order to give a relative bond length in relation to the given.
by yuetao4k
Mon Nov 12, 2018 12:15 am
Forum: Lewis Structures
Topic: Formal Charge
Replies: 14
Views: 151

Re: Formal Charge

To let the structure be as stable as possible, a charge of 0 is the most stable. The outer elements can have a charge as long as the charges are symmetrical for it to still be stable.
by yuetao4k
Mon Nov 12, 2018 12:13 am
Forum: Octet Exceptions
Topic: Octet exceptions
Replies: 8
Views: 120

Re: Octet exceptions

Elements that are past the 3rd period can have an expanded octet, but it depends on what the compound is to determine whether or not it needs to use an expanded octet.
by yuetao4k
Fri Nov 02, 2018 3:46 pm
Forum: Bond Lengths & Energies
Topic: Test 3 bond length question
Replies: 8
Views: 258

Re: Test 3 bond length question

Longer bonds mean that they are weaker.
by yuetao4k
Fri Nov 02, 2018 3:45 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 9
Views: 235

Re: Bond Length

Single bonds are longer than double bonds, and double bonds are longer than triple bonds. This is because of the strength of the bonds.
by yuetao4k
Fri Nov 02, 2018 3:41 pm
Forum: Bond Lengths & Energies
Topic: Lengths of Bonds
Replies: 9
Views: 88

Re: Lengths of Bonds

Double bonds are shorter than single bonds because double bonds are stronger and more attracted to the protons in the nucleus. Single bonds are as strong, therefore they are not going to be as attracted to the nucleus.
by yuetao4k
Sun Oct 28, 2018 8:35 pm
Forum: *Shrodinger Equation
Topic: Application of Equation on test
Replies: 5
Views: 117

Re: Application of Equation on test

We don’t need to know how to use it to calculate anything.
by yuetao4k
Sun Oct 28, 2018 8:34 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Delta X relationship with Delta P
Replies: 3
Views: 77

Re: Delta X relationship with Delta P

If delta x increases, then delta p will decrease.
by yuetao4k
Sun Oct 28, 2018 8:14 pm
Forum: Quantum Numbers and The H-Atom
Topic: Degeneracy
Replies: 5
Views: 86

Re: Degeneracy

To add on, if the orbital you’re talking about isn’t the p orbital, how do you know the degeneracy?
by yuetao4k
Sun Oct 21, 2018 11:09 pm
Forum: Trends in The Periodic Table
Topic: Largest in Atomic Radii?
Replies: 5
Views: 74

Re: Largest in Atomic Radii?

More protons means that the pull on electrons surrounding the atom is greater. This pull makes the atomic radius smaller.
by yuetao4k
Sun Oct 21, 2018 10:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Symmetric vs. Non symmetric orbitals
Replies: 4
Views: 81

Re: Symmetric vs. Non symmetric orbitals

The symmetry helps us understand how the structures are shaped.
by yuetao4k
Sun Oct 21, 2018 9:58 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 16
Views: 107

Re: Work Function

Josephine Lu 1L wrote:Is the unit of work function Joules, or Joules per photon?


The unit for work is joules! And joules = kg.m^2.s^-2
by yuetao4k
Mon Oct 15, 2018 12:48 am
Forum: Limiting Reactant Calculations
Topic: Percent Yield [ENDORSED]
Replies: 13
Views: 285

Re: Percent Yield [ENDORSED]

More often than not, the actual yield will be less than the theoretical yield because in reactions, there is always room to make error and chemical products and reactants could "escape" the experiment. The actual yield is the yield you get from conducting the experiment in real life, and t...
by yuetao4k
Mon Oct 15, 2018 12:46 am
Forum: Empirical & Molecular Formulas
Topic: Is it possible for the Empirical and Molecular formula to be the same? [ENDORSED]
Replies: 8
Views: 205

Re: Is it possible for the Empirical and Molecular formula to be the same? [ENDORSED]

It is completely possible! If the given molecular weight is calculated to be the same as the empirical formula's molecular weight, then it is the same!
by yuetao4k
Mon Oct 15, 2018 12:45 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: diatomic elements
Replies: 12
Views: 257

Re: diatomic elements

Diatomic elements only need to exist in pairs of atoms when they are standing alone. For instance, in OH-, you wouldn't need two hydrogen atoms because the hydrogen is not free standing. However, if you have hydrogen gas, you would need H2 because it is not attached to a different element.
by yuetao4k
Sun Oct 07, 2018 2:10 pm
Forum: Molarity, Solutions, Dilutions
Topic: Rounding molar mass
Replies: 4
Views: 61

Re: Rounding molar mass

I always use three decimals for the molar mass from the given periodic table masses. At the very end of the problem is when I round any number that I use in my calculations. This ensures that I don't miss anything or have any miscalculations.
by yuetao4k
Sun Oct 07, 2018 2:08 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Formula
Replies: 12
Views: 92

Re: Molecular Formula

If atoms are linked together, they form one compound. Count up each type of atom to form the compounds used in the equation and use them to make a balanced chemical equation.
by yuetao4k
Sun Oct 07, 2018 2:06 pm
Forum: Significant Figures
Topic: Rounding numbers ending in 5
Replies: 9
Views: 70

Re: Rounding numbers ending in 5

I usually use the most exact number (from the calculator) when dealing with the problem, and at the very end, I round to however many significant figures there are given from the problem.

Go to advanced search