Search found 52 matches

by Hadji Yono-Cruz 2L
Mon Feb 18, 2019 2:22 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q VS. K
Replies: 9
Views: 68

Re: Q VS. K

Q and K are calculated in the same way. Q is calculated at any point of the reaction, but K is calculated only at equilibrium. If Q is less than K then the products are favored. If Q is less than K then the reactants are favored.
by Hadji Yono-Cruz 2L
Mon Feb 18, 2019 2:20 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K constant
Replies: 5
Views: 139

Re: K constant

Brackets means that the K is Kc and should be in terms of concentration. P means that K is Kp and should be in terms of partial pressure.
by Hadji Yono-Cruz 2L
Mon Feb 18, 2019 2:18 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible vs. Irreversible
Replies: 5
Views: 19

Re: Reversible vs. Irreversible

For a reversible reaction, you use w=-nRT ln (v2/v1) and for an irreversible reaction, you use w=-Pex times delta V.
by Hadji Yono-Cruz 2L
Sun Feb 17, 2019 11:08 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Residual Entropy
Replies: 2
Views: 11

Residual Entropy

I know boltzman equation is S= k ln W, but when am I supposed to use S= R Ln W ( k times avogadro's number is R)?
by Hadji Yono-Cruz 2L
Mon Feb 11, 2019 5:05 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed systems
Replies: 6
Views: 39

Re: closed systems

They can have both be constant or changing.
by Hadji Yono-Cruz 2L
Mon Feb 11, 2019 3:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 7.71 [ENDORSED]
Replies: 5
Views: 1871

Re: 7.71 [ENDORSED]

The question is asking what is the standard enthalpy formation of N2O5, not the overall reaction. From the chemical equation, O2 is in its natural state, so the enthalpy for O2 is 0. We are also given the standard enthalpy of formation for NO which is 90.25 KJ. With this information we know that del...
by Hadji Yono-Cruz 2L
Sun Feb 10, 2019 3:23 pm
Forum: Ideal Gases
Topic: The Difference between Q and Kc
Replies: 11
Views: 62

Re: The Difference between Q and Kc

Q and K are calculated the same way (products/reactants), but Q can be measured at any point of the reaction and K is only measured at equilibrium. If Q < K then the forward reaction is favored. If Q > K then the reverse reaction is favored.
by Hadji Yono-Cruz 2L
Thu Feb 07, 2019 3:23 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 10
Views: 77

Re: Le Chatelier's Principle

If you shift the partial pressure of the product, then equilibrium will shift to the reactants. If you shift partial pressure of a reactant, then equilibrium will shift towards the products. If you introduce an inert gas that is not involved in the chemical reaction then equilibrium will remain unch...
by Hadji Yono-Cruz 2L
Thu Feb 07, 2019 3:18 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Le Chateliers Priniciple
Replies: 9
Views: 59

Re: Le Chateliers Priniciple

An increase in pressure means a decrease in volume, so equilibrium will shift to the side where there are less moles of gas.
by Hadji Yono-Cruz 2L
Thu Feb 07, 2019 3:13 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding Inert Gas
Replies: 10
Views: 68

Re: Adding Inert Gas

When a reaction vessel has an inert gas pumped into it at a constant volume to increase the total pressure, then the total pressure will increase but the partial pressures of the reactants and products are unchanged and therefore the K value will not be affected.
by Hadji Yono-Cruz 2L
Sat Feb 02, 2019 10:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 6
Views: 36

Re: Inert Gas

As long as there is no change in volume, then equilibrium will not be shifted because the inert gas is not included in the chemical reaction.
by Hadji Yono-Cruz 2L
Sat Feb 02, 2019 10:14 pm
Forum: Phase Changes & Related Calculations
Topic: PΔV of Solids and Liquids
Replies: 4
Views: 33

Re: PΔV of Solids and Liquids

Solids and liquids do not compress or expand, so their volume does not change.
by Hadji Yono-Cruz 2L
Sat Feb 02, 2019 10:12 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: delta H vs q
Replies: 9
Views: 41

Re: delta H vs q

Delta H is the change in enthalpy and q represents heat.
by Hadji Yono-Cruz 2L
Wed Jan 23, 2019 11:46 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Module 2
Replies: 3
Views: 503

Re: Module 2

I did the same thing as explained above and I get Kc=[BrCl]^2/[Br2][Cl2]=[3.37 x 10^-5]^2/[7.52 x 10^-5][7.52 x 10^-5]. My answer: 0.199637845, however, is not an answer choice can someone please explain what I did wrong? Thank you! I made this mistake as well. The question should be answered in te...
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure
Replies: 7
Views: 39

Pressure

When determining the moles of the reaction in terms of pressure, do we include the number of moles of solids and liquids in the reaction or just the gases?
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:22 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Removing products
Replies: 10
Views: 41

Re: Removing products

Removing products would only affect Q because only temperature causes the K value to change.
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changing partial pressure of components vs changing pressure of system
Replies: 2
Views: 26

Re: Changing partial pressure of components vs changing pressure of system

If pressure increases then that means volume decreases, so reaction will shift toward the side with less gas moles.

If pressure decreases then that means volume increases, so reaction will shift toward the side with more gas moles.
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5%
Replies: 5
Views: 29

Re: 5%

5% refers to the x value and if it is less than 5% then x will be insignificant to calculations, so the quadratic formula would not have to be used and you can simply plug in the values that are given.
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:14 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in Temperature
Replies: 8
Views: 38

Re: Changes in Temperature

For endothermic reactions: If temperature increases, then the forward reaction is favored. If temperature decreases, then the reverse reaction is favored. For exothermic reactions: If temperature increases, then the reverse reaction is favored. If temperature decreases, then the forward reaction is ...
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:06 pm
Forum: Ideal Gases
Topic: K value
Replies: 8
Views: 65

Re: K value

K=1 is rare because there is a 1:1 ratio of reactants to products and that is usually never seen in real life applications.
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:04 pm
Forum: Ideal Gases
Topic: kc vs kp
Replies: 15
Views: 70

Re: kc vs kp

Kp cannot be used in place for Kc, but you can convert one into the other by using the formula: Kp= Kc(RT)^delta n. Delta n is equal to the moles of the products minus the moles of the reactants. This formula relates Kp to Kc, so you can convert one to the other.
by Hadji Yono-Cruz 2L
Sun Jan 20, 2019 11:00 pm
Forum: Ideal Gases
Topic: PV=nRT
Replies: 7
Views: 61

Re: PV=nRT

For most problems R and T are constants and will be given in the problem. This formula is generally used to find pressure or concentration.
by Hadji Yono-Cruz 2L
Sat Dec 01, 2018 6:15 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Lengths
Replies: 10
Views: 113

Re: Bond Lengths

You can add the bond lengths together and divide by the total amount of resonance structures to find the average bond length.
by Hadji Yono-Cruz 2L
Sat Dec 01, 2018 1:28 am
Forum: Hybridization
Topic: S character
Replies: 3
Views: 59

Re: S character

s-character is the contribution of the sigma type bond in hybridization So, if you have sp, it is a 50-50 percent s-p character ratio, while sp2 has a ratio of 33-66 and sp3 has a ratio of 25 to 75 s character to p character. It's simply the percent that the s takes up in hybridization. This is cor...
by Hadji Yono-Cruz 2L
Sat Dec 01, 2018 1:22 am
Forum: Hybridization
Topic: Bond Strengths
Replies: 4
Views: 56

Re: Bond Strengths

A C=C double bond is stronger than a single bond but it is weaker than the sum of 2 single C-C bonds. Sigma bonds are harder to break than pi bonds because sigma bonds have their overlap closer to both of the atom's nuclei and the electrons are more attracted to the nuclei because of the positive ch...
by Hadji Yono-Cruz 2L
Wed Nov 28, 2018 4:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: linear vs bent question
Replies: 7
Views: 64

Re: linear vs bent question

The bent shape comes from the lone electron pair because that region counts as an area of electron density. That lone pair causes a repulsion for the other electrons which push the other bond angles closer together.
by Hadji Yono-Cruz 2L
Wed Nov 28, 2018 3:08 pm
Forum: Lewis Structures
Topic: Lewis structures vs VSEPR
Replies: 2
Views: 39

Lewis structures vs VSEPR

Just to be clear, when we draw lewis structures we draw the electrons of the atoms, but when we draw the VSEPR model we do not include the electrons? We only include the shared electrons?
by Hadji Yono-Cruz 2L
Wed Nov 28, 2018 1:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Week 8 Worksheet (3A3I3K)
Replies: 5
Views: 391

Re: Week 8 Worksheet (3A3I3K)

Thanks Joyce!
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 3:24 pm
Forum: Coordinate Covalent Bonds
Topic: Difference between coordinate covalent and covalent bond
Replies: 3
Views: 42

Difference between coordinate covalent and covalent bond

What is the difference between a coordinate covalent bond and covalent bond? How can you identify if a molecule has a coordinate covalent bond or a covalent bond?
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 3:20 pm
Forum: Significant Figures
Topic: Calculating process
Replies: 5
Views: 174

Re: Calculating process

Round your answer at the end to avoid errors in your calculations beforehand.
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 3:13 pm
Forum: Empirical & Molecular Formulas
Topic: Limiting Reactants
Replies: 3
Views: 79

Re: Limiting Reactants

You can use either of the products to find the limiting reactant. Just make sure that you use the same product (does not matter which you choose) when comparing the reactants. However, on a test the next subquestion might ask about a specific product, so it may be more beneficial to choose that one ...
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 3:10 pm
Forum: Sigma & Pi Bonds
Topic: Why are sigma bonds stronger than pi bonds?
Replies: 10
Views: 86

Re: Why are sigma bonds stronger than pi bonds?

Sigma bonds head-on overlap puts the electron closer to the other atom's nucleus. The pi bonds overlap does not put the electron as close in comparison to the sigma bond, so the sigma bond is stronger.
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 2:00 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical & Molecular Formulas
Replies: 11
Views: 331

Re: Empirical & Molecular Formulas

Yes they can, if the combined mass of the empirical formula is the same as the molecular mass given then they are the same.
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 1:56 pm
Forum: Sigma & Pi Bonds
Topic: Which bond would break first.
Replies: 11
Views: 90

Re: Which bond would break first.

Pi bonds would break first because their electrons are more spread out than those of sigma bonds. The electrons in a sigma bond are directly between the two nuclei and are harder to break.
by Hadji Yono-Cruz 2L
Tue Nov 27, 2018 1:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond lengths
Replies: 1
Views: 12

Bond lengths

How can you tell what atom has a shorter or longer bond length when comparing atoms and ions? For example, rank the molecules from smallest to largest N-O bond length.

NO2-, NO3-, NO+, NO
by Hadji Yono-Cruz 2L
Mon Nov 05, 2018 4:49 pm
Forum: Trends in The Periodic Table
Topic: Periodic Trends in Relation
Replies: 3
Views: 79

Re: Periodic Trends in Relation

Can someone explain the reasons behind the trends we see in the periodic table? - Atomic radius - Ionization energy - Electronegativity How do they relate to shielding effect and number of electrons or protons? Atomic radius increases going down the periodic table because a valence electron is adde...
by Hadji Yono-Cruz 2L
Sat Nov 03, 2018 12:38 am
Forum: Trends in The Periodic Table
Topic: Ionization energy and electronegativity
Replies: 1
Views: 50

Ionization energy and electronegativity

Since both ionization energy and electronegativity are the energies to remove an electron, then what is the difference between them? Does ionization energy refer only to ionic bonds and electronegativity refers to covalent bonds?
by Hadji Yono-Cruz 2L
Sat Nov 03, 2018 12:35 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cu and Cr electron configuration exceptions
Replies: 1
Views: 50

Cu and Cr electron configuration exceptions

Why do Cu and Cr not follow the same trend of writing the electron configuration as other atoms?
by Hadji Yono-Cruz 2L
Fri Oct 26, 2018 8:39 pm
Forum: General Science Questions
Topic: Midterm studying
Replies: 10
Views: 225

Midterm studying

What are some methods for studying for the midterm that people have found helpful?
by Hadji Yono-Cruz 2L
Fri Oct 26, 2018 8:33 pm
Forum: Quantum Numbers and The H-Atom
Topic: Degeneracy
Replies: 4
Views: 102

Re: Degeneracy

I do not understand the importance of degeneracy.
by Hadji Yono-Cruz 2L
Thu Oct 25, 2018 8:08 pm
Forum: DeBroglie Equation
Topic: Given the energy, calculate the wavelength of y-rays
Replies: 5
Views: 894

Re: Given the energy, calculate the wavelength of y-rays

Ahhh thank you for the explanation.
by Hadji Yono-Cruz 2L
Tue Oct 16, 2018 3:02 pm
Forum: Molarity, Solutions, Dilutions
Topic: G7
Replies: 2
Views: 768

Re: G7

Ok so to start off we have to find out how much grams of KNO3 are in the sample of 510 g The first step is to to get 5.45 from a percentage to a decimal so we divide it by 100 and it becomes .0545. Then we multiply .0545 by the 510 g to get how much grams of KNO3 were in this aqueous solution which...
by Hadji Yono-Cruz 2L
Thu Oct 11, 2018 2:58 pm
Forum: Properties of Light
Topic: HW 1.7 6th Edition Part B
Replies: 2
Views: 52

HW 1.7 6th Edition Part B

1.7 (a) The frequency of violet light is 7.1 " 1014 Hz. What is the wavelength (in nanometers) of violet light? (b) When an electron beam strikes a block of copper, x-rays with a frequency of 2.0 " 1018 Hz are emitted. What is the wavelength (in picometers) of these x-rays. The answer for ...
by Hadji Yono-Cruz 2L
Thu Oct 11, 2018 2:01 pm
Forum: Properties of Light
Topic: Chapter 1 Homework Question [ENDORSED]
Replies: 6
Views: 1544

Re: Chapter 1 Homework Question [ENDORSED]

Electromagnetic radiation is another word for energy propagated through free space or through a material medium in the form of electromagnetic waves. Therefore, we can think of this as light since it is a type of electromagnetic wave. Looking at the equation for energy per photon of light, E = h\nu...
by Hadji Yono-Cruz 2L
Thu Oct 11, 2018 10:35 am
Forum: Student Social/Study Group
Topic: Studying techniques
Replies: 12
Views: 161

Studying techniques

What are some effective ways to study for chemistry?
by Hadji Yono-Cruz 2L
Sat Oct 06, 2018 6:41 pm
Forum: Administrative Questions and Class Announcements
Topic: 3I 3K Discussion Notes
Replies: 1
Views: 148

Re: 3I 3K Discussion Notes

These are very helpful! Thank you!
by Hadji Yono-Cruz 2L
Thu Oct 04, 2018 11:18 am
Forum: Empirical & Molecular Formulas
Topic: L35
Replies: 3
Views: 918

Re: L35

First, you must convert the 2.50 t of NaBr to grams using the conversion factor 1.0 x 10^6 grams = 1 ton. Then you find the molar mass of NaBr (102.89g) and divide the grams of NaBr by NaBr's molar mass. Next, find the mole ratio between Fe and NaBr which is 3 mol Fe: 8 mol NaBr (don't forget to ma...
by Hadji Yono-Cruz 2L
Sun Sep 30, 2018 11:17 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7023
Views: 771891

Re: Post All Chemistry Jokes Here

I asked the guy sitting next to me if he had any Sodium Hypobromite
He said NaBrO
by Hadji Yono-Cruz 2L
Sun Sep 30, 2018 11:14 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 33105

Re: Rusty on High School Chem [ENDORSED]

Adding on from other people's suggestions, look up Tyler Dewitt on Youtube. He is really good at teaching chemistry and helped me get through my AP chemistry class in high school.
by Hadji Yono-Cruz 2L
Sat Sep 29, 2018 12:18 pm
Forum: Significant Figures
Topic: Significant Figures
Replies: 10
Views: 148

Significant Figures

When using significant figures, do you use significant figures throughout your whole calculation (for example if the given significant figures is 2, but I am using molar mass and the molar mass contains 4 significant figures then do I change the molar mass to 2 significant figures or leave as is) or...

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