Search found 79 matches

by stephaniekim2K
Sun Feb 09, 2020 7:48 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Expansion work/ Compression
Replies: 7
Views: 30

Re: Expansion work/ Compression

During expansion, work is being done so you need a negative sign while compression you need a positive sign.
by stephaniekim2K
Sun Feb 09, 2020 7:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Negative Heat Capacity
Replies: 4
Views: 19

Re: Negative Heat Capacity

No, because you can't have a negative value for the amount of energy required to raise the temperature.
by stephaniekim2K
Sun Feb 09, 2020 7:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 5
Views: 20

Re: Calorimeter

A calorimeter measure the heat change when a reaction occurs. A bomb calorimeter, though, has constant volume.
by stephaniekim2K
Sun Feb 09, 2020 7:31 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeters
Replies: 17
Views: 48

Re: Calorimeters

A bomb calorimeter is constant volume.
by stephaniekim2K
Sun Feb 09, 2020 7:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter and Bomb Calorimeter
Replies: 4
Views: 18

Re: Calorimeter and Bomb Calorimeter

A calorimeter measures the change in temperature, but a bomb calorimeter has constant volume.
by stephaniekim2K
Sun Feb 09, 2020 7:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Closed Systems
Replies: 13
Views: 35

Re: Closed Systems

Energy cannot leave in a closed system, so only temperature or pressure can change.
by stephaniekim2K
Sun Feb 09, 2020 7:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp/Cv
Replies: 7
Views: 27

Re: Cp/Cv

Unless stated, just assume that it is at constant pressure.
by stephaniekim2K
Sun Feb 02, 2020 10:03 am
Forum: Phase Changes & Related Calculations
Topic: Enthalpy vs Change in Internal Energy
Replies: 4
Views: 12

Re: Enthalpy vs Change in Internal Energy

Enthalpy is the heat absorbed/released while internal energy is just the total amount of energy.
by stephaniekim2K
Sun Feb 02, 2020 10:02 am
Forum: Phase Changes & Related Calculations
Topic: Calorimeter
Replies: 8
Views: 26

Re: Calorimeter

A bomb calorimeter is more resistant to pressure.
by stephaniekim2K
Sat Feb 01, 2020 10:29 pm
Forum: Phase Changes & Related Calculations
Topic: DELTA H Vs Q
Replies: 7
Views: 29

Re: DELTA H Vs Q

Delta H is based on the amount of substance used while Q is the amount of energy released in total.
by stephaniekim2K
Sat Feb 01, 2020 10:28 pm
Forum: Phase Changes & Related Calculations
Topic: Open vs Isolated System
Replies: 15
Views: 51

Re: Open vs Isolated System

In a closed system, energy cannot be transferred to the outside.
by stephaniekim2K
Sat Feb 01, 2020 10:27 pm
Forum: Phase Changes & Related Calculations
Topic: Why does steam cause burns?
Replies: 29
Views: 108

Re: Why does steam cause burns?

Steam has more energy than liquid because more energy is required to transform a liquid into steam. For this reason, as steam touches the skin, much more energy is transferred, causing burns.
by stephaniekim2K
Sun Jan 26, 2020 10:12 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and Kb
Replies: 10
Views: 27

Re: Ka and Kb

Yes, although I believe strong acids and bases have K values, they are so excessively big.
by stephaniekim2K
Sun Jan 26, 2020 10:11 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endothermic
Replies: 8
Views: 22

Re: endothermic

If a reaction is endothermic, heat is required so adding heat to is would favor the reactants.
by stephaniekim2K
Sun Jan 26, 2020 10:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: exothermic reactions
Replies: 19
Views: 70

Re: exothermic reactions

In an exothermic reaction, heat is produced, so there is heat in the products. Adding heat to the reaction would favor the reactants.
by stephaniekim2K
Sun Jan 26, 2020 10:07 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Gas Constant
Replies: 13
Views: 29

Re: Gas Constant

There's a few different gas constants for different units but they are the same constant, just with different units. They are all on the formula sheet.
by stephaniekim2K
Sun Jan 26, 2020 10:04 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Clarification on example
Replies: 2
Views: 14

Re: Clarification on example

pH is equal to the -log[H3o+] so the lower the concentration of [H3O], the smaller the pH, meaning it is a strong acid. Since the pH of H2O is 7, neutral, [H3O]=107.
by stephaniekim2K
Sun Jan 26, 2020 9:59 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

If the acid or base isn't dissociated completely, it is weak. Otherwise, a very low or a very high pH (or a very high or a very low pOH) means it is a strong acid or base.
by stephaniekim2K
Sun Jan 26, 2020 9:52 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: removing H2 from N2 + 3H2 -> 2NH3
Replies: 7
Views: 26

Re: removing H2 from N2 + 3H2 -> 2NH3

Removing H2 would make the reaction shift toward the reactants because of Le Chatlier's, so more N2 would be produced.
by stephaniekim2K
Sun Jan 26, 2020 9:51 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Finding Ka from pH
Replies: 5
Views: 23

Re: Finding Ka from pH

[H30+]=-logpH and [OH-]=-logpOH.
by stephaniekim2K
Tue Jan 21, 2020 1:35 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Kc vs K
Replies: 7
Views: 18

Re: Kc vs K

Kc is the equilibrium constant that's calculated by the concentrations but it is calculated the same way as just "K."
by stephaniekim2K
Tue Jan 21, 2020 1:22 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X was ignored
Replies: 27
Views: 81

Re: X was ignored

Since Ka is smaller than 103 you can ignore the x in the denominator. Since K is so small, x is negligible in this case and can be ignored for the sake of convenience of calculating.
by stephaniekim2K
Tue Jan 21, 2020 1:18 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pKa and pKb
Replies: 17
Views: 52

Re: pKa and pKb

p just means its the log of something. so pKa is log(Ka) and pKb is log(Kb).
by stephaniekim2K
Tue Jan 21, 2020 1:10 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: temperature
Replies: 10
Views: 35

Re: temperature

Temperature affects the equilibrium constant so if the reaction is exothermic (heat in the products) added heat will shift the reaction left and removing heat will shift the reaction right. On the other hand, if the reaction is endothermic (heat in reactants) added heat will shift the reaction right...
by stephaniekim2K
Tue Jan 21, 2020 1:08 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sig Figs for pH/pOH
Replies: 7
Views: 32

Re: Sig Figs for pH/pOH

The number of sig figs to the answer of a log is the amount of sig figs after the decimal of the number you took the log of.
by stephaniekim2K
Tue Jan 21, 2020 1:07 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H20 in the ICE table
Replies: 26
Views: 91

Re: H20 in the ICE table

You include any gases, but since solids and liquids have negligible change they are not included in ice box or the equilibrium constant.
by stephaniekim2K
Tue Jan 21, 2020 12:59 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Directionality of Acid/Base Equations
Replies: 4
Views: 17

Re: Directionality of Acid/Base Equations

Weak acids and bases are reversible because they don't dissociate completely, but strong acids and bases on the other hand dissociate completely so they are not reversible.
by stephaniekim2K
Tue Jan 21, 2020 12:58 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: lewis structure
Replies: 11
Views: 32

Re: lewis structure

No he only draws the structures for clarity but they are only for 14a not 14b.
by stephaniekim2K
Sun Jan 12, 2020 11:17 pm
Forum: Ideal Gases
Topic: Kc and Kp
Replies: 8
Views: 19

Re: Kc and Kp

Kc is solved using concentration while Kp is solved using partial pressures.
by stephaniekim2K
Sun Jan 12, 2020 11:16 pm
Forum: Ideal Gases
Topic: Understanding Q
Replies: 19
Views: 70

Re: Understanding Q

Q is solved the same way as K, Q is just not at equilibrium.
by stephaniekim2K
Sun Jan 12, 2020 11:15 pm
Forum: Ideal Gases
Topic: PV = nRT
Replies: 16
Views: 55

Re: PV = nRT

P=pressure
V=volume
N=moles
R= ideal gas constant
T=temperature
by stephaniekim2K
Sun Jan 12, 2020 11:14 pm
Forum: Ideal Gases
Topic: Q vs. K
Replies: 10
Views: 25

Re: Q vs. K

K is the constant at equilibrium while Q is the constant at any point in the reaction.
by stephaniekim2K
Sun Jan 12, 2020 11:13 pm
Forum: Ideal Gases
Topic: Vapor Pressure
Replies: 4
Views: 19

Re: Vapor Pressure

When the gas and liquid states are at equilibrium, the pressure of the gas is known as the vapor pressure.
by stephaniekim2K
Tue Jan 07, 2020 11:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.3
Replies: 8
Views: 58

Re: 5G.3

Partial pressure is used in this case because they are gases.
by stephaniekim2K
Tue Jan 07, 2020 11:15 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Heterogenous vs. Homogenous equations
Replies: 6
Views: 33

Re: Heterogenous vs. Homogenous equations

Homogeneous equations are all in the same state of matter, while heterogeneous are in mixed states of matter.
by stephaniekim2K
Tue Jan 07, 2020 11:14 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Very Large K
Replies: 12
Views: 67

Re: Very Large K

Seeing as the formula for K is K = [P]/[R], the larger the concentration of products and the smaller the concentration of reactants there are, the larger K will be.
by stephaniekim2K
Mon Jan 06, 2020 5:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kc
Replies: 4
Views: 44

Re: Calculating Kc

Solids and liquids have constant concentrations so they don't change, so there is no need to calculate them.
by stephaniekim2K
Mon Jan 06, 2020 5:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant
Replies: 3
Views: 28

Re: Equilibrium Constant

According to the constant formula (K = [P]/[R]) the value of K will be higher, meaning there is more product than reactant left at the end. This being said, a more stable molecule results in more product and less reverse reaction happening.
by stephaniekim2K
Sun Dec 01, 2019 11:25 pm
Forum: Naming
Topic: Chelating
Replies: 6
Views: 45

Re: Chelating

A ligand is a chelate when it bonds in more than one area.
by stephaniekim2K
Sun Dec 01, 2019 11:24 pm
Forum: Naming
Topic: -bis, -tris, etc
Replies: 5
Views: 47

Re: -bis, -tris, etc

You use these suffixes when there is already a suffix in the name.
by stephaniekim2K
Sun Dec 01, 2019 11:24 pm
Forum: Naming
Topic: How to Know the Charge of Ions
Replies: 7
Views: 46

Re: How to Know the Charge of Ions

You will have to memorize the polyatomic ions, but I'm pretty sure he won't give anything that's too difficult.
by stephaniekim2K
Sun Dec 01, 2019 11:23 pm
Forum: Naming
Topic: When to change to -ate?
Replies: 3
Views: 19

Re: When to change to -ate?

If the charge is negative you add -ate.
by stephaniekim2K
Sun Dec 01, 2019 11:21 pm
Forum: Naming
Topic: Brackets in Chem. Formula
Replies: 5
Views: 32

Re: Brackets in Chem. Formula

The transition metal and its ligands go inside the bracket. Everything else is outside.
by stephaniekim2K
Sun Nov 24, 2019 11:11 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 18
Views: 110

Re: Resonance Structures

They are structure with the same formal charges.
by stephaniekim2K
Sun Nov 24, 2019 11:09 pm
Forum: Resonance Structures
Topic: Bond length
Replies: 5
Views: 48

Re: Bond length

Yes they are all the same.
by stephaniekim2K
Sun Nov 24, 2019 11:09 pm
Forum: Resonance Structures
Topic: Resonance and Naming
Replies: 11
Views: 56

Re: Resonance and Naming

No, because it is the same structure it has the same name.
by stephaniekim2K
Sun Nov 24, 2019 11:08 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 15
Views: 93

Re: Resonance structures

Resonance structures are different ways a lewis structure can be drawn, but they have the same formal charge.
by stephaniekim2K
Sun Nov 24, 2019 11:05 pm
Forum: Resonance Structures
Topic: Lone Pairs
Replies: 3
Views: 31

Re: Lone Pairs

Lone pairs position themselves in a way where there is minimal repulsion.
by stephaniekim2K
Sat Nov 16, 2019 10:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs. Nonpolar
Replies: 12
Views: 80

Re: Polar vs. Nonpolar

You need to draw the lewis structure and it helps to draw arrows to the negative charged atom from the positively charged ion. If there are two different poles, then the molecule is polar, if both cancel out, it is nonpolar.
by stephaniekim2K
Sat Nov 16, 2019 10:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E 11 b)
Replies: 4
Views: 20

Re: 2E 11 b)

Chlorine cannot have more than a single bond so we know that there are 3 single bonds on iodine, meaning there will be two left over lone pairs on iodine.
by stephaniekim2K
Sat Nov 16, 2019 9:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar or non polar?
Replies: 7
Views: 41

Re: polar or non polar?

You need both to figure out if it is polar/nonpolar. Electronegativity will tell where the pull of electrons is, but the Lewis structure shows the positioning of the atoms and whether they will cancel or not.
by stephaniekim2K
Sun Nov 10, 2019 9:03 pm
Forum: Electronegativity
Topic: Karen's worksheet #12
Replies: 3
Views: 58

Re: Karen's worksheet #12

There is a greater difference in electronegativity.
by stephaniekim2K
Sun Nov 10, 2019 8:58 pm
Forum: Electronegativity
Topic: ionic character
Replies: 9
Views: 64

Re: ionic character

Ionic character, I believe, is a covalently bond that has such strong ionic character (electronegativity) that a covalently bonded substance is almost ionic.
by stephaniekim2K
Sun Nov 10, 2019 8:57 pm
Forum: Electronegativity
Topic: Ionic or covalent?
Replies: 17
Views: 110

Re: Ionic or covalent?

An ionic bond is typically comprised of a non metal and a metal while a covalent bond is usually two non metals.
by stephaniekim2K
Sun Nov 10, 2019 8:56 pm
Forum: Electronegativity
Topic: memorizing tables
Replies: 9
Views: 41

Re: memorizing tables

Just know the general trend on the periodic table.
by stephaniekim2K
Sun Nov 10, 2019 8:56 pm
Forum: Electronegativity
Topic: Ionization Energy vs. Electronegativity
Replies: 9
Views: 53

Re: Ionization Energy vs. Electronegativity

Both ionization energy and electronegativity increase toward the upper right hand side of the periodic table.
by stephaniekim2K
Sun Nov 10, 2019 8:54 pm
Forum: Electronegativity
Topic: Electron Affinity and Electronegativity
Replies: 7
Views: 26

Re: Electron Affinity and Electronegativity

Electron affinity is the energy released when an electron in added to to an atom, while electronegativity is how much an atom pulls electrons.
by stephaniekim2K
Sun Nov 10, 2019 8:49 pm
Forum: Octet Exceptions
Topic: Incomplete octets
Replies: 3
Views: 38

Re: Incomplete octets

Hydrogen, helium, and boron are all exceptions to the rule.
by stephaniekim2K
Wed Oct 30, 2019 9:04 pm
Forum: Lewis Structures
Topic: Lone Pairs
Replies: 10
Views: 54

Re: Lone Pairs

Lone pair electrons are electrons that are not bonded to other elements. In other words, they are not shared with any other elements.
by stephaniekim2K
Wed Oct 30, 2019 9:03 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet Rule
Replies: 3
Views: 25

Re: Exceptions to the Octet Rule

Elements P, Cl, and S do not adhere to the octet rule because of the d orbital.
by stephaniekim2K
Wed Oct 30, 2019 9:01 pm
Forum: Lewis Structures
Topic: Creating Lewis Structures
Replies: 7
Views: 54

Re: Creating Lewis Structures

Typically, the element with the lowest ionization energy will go in the center.
by stephaniekim2K
Wed Oct 30, 2019 8:59 pm
Forum: Lewis Structures
Topic: Valence electrons
Replies: 5
Views: 47

Re: Valence electrons

Sulfur, Phosphorous, and Chlorine all deviate from the octet rule because they have the extra d orbitals.
by stephaniekim2K
Wed Oct 30, 2019 8:58 pm
Forum: Lewis Structures
Topic: Drawing lewis structures
Replies: 8
Views: 53

Re: Drawing lewis structures

If the question asks for Lewis structures, I assume it is just the 2D model without angles. I'm sure if we learn about bond angles there will be a separate question.
by stephaniekim2K
Sun Oct 20, 2019 11:48 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 13
Views: 79

Re: Speed of light

Typically, if not mentioned, you use the speed of light in a vacuum.
by stephaniekim2K
Sun Oct 20, 2019 11:39 pm
Forum: Properties of Light
Topic: Combining Different Equations
Replies: 8
Views: 61

Re: Combining Different Equations

Sometimes you are given some info but not others, so in order to solve with the info given you can rearrange them to fit the info you have.
by stephaniekim2K
Sun Oct 20, 2019 11:36 pm
Forum: Properties of Light
Topic: Constant for Speed of Light
Replies: 14
Views: 86

Re: Constant for Speed of Light

For tests at least, I used the constant given on the front sheet and I got full points for the problem.
by stephaniekim2K
Sun Oct 20, 2019 11:35 pm
Forum: Properties of Light
Topic: Unit Conversions
Replies: 6
Views: 61

Re: Unit Conversions

I find it easier to convert when you first convert to meters, then to the needed measurement from there.
by stephaniekim2K
Sun Oct 20, 2019 11:33 pm
Forum: Properties of Light
Topic: What are the units of hertz
Replies: 41
Views: 239

Re: What are the units of hertz

The unit is 1/s which is essentially s^-1
by stephaniekim2K
Sun Oct 20, 2019 11:32 pm
Forum: Properties of Electrons
Topic: Angstrom Conversion
Replies: 12
Views: 103

Re: Angstrom Conversion

1 Angstrom is equal to 10^-10 meters
by stephaniekim2K
Fri Oct 11, 2019 4:04 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 41
Views: 944

Re: Speed of Light

3.00 x 10^8 is the speed of light inside a vacuum.
by stephaniekim2K
Fri Oct 11, 2019 4:03 pm
Forum: Properties of Light
Topic: Frequency and Hertz
Replies: 5
Views: 53

Re: Frequency and Hertz

The unit is simply second^-1 or 1/s.
by stephaniekim2K
Fri Oct 11, 2019 3:58 pm
Forum: Properties of Light
Topic: Relationship between lambda and nu
Replies: 5
Views: 67

Re: Relationship between lambda and nu

Based on the equation for the speed of light, c = λ ν, c is a constant, so λ and ν are inversely proportional because they are being multiplied. As one goes up, the other value must go down, and vice versa. For example, if λ, the wavelength goes up in value, the frequency, ν, must respond accordingl...
by stephaniekim2K
Fri Oct 11, 2019 3:55 pm
Forum: Properties of Light
Topic: Clarification on Frequency
Replies: 8
Views: 87

Re: Clarification on Frequency

Since C=λν, frequency and wavelength are inversely proportional, meaning that as one increases, the other decreases since the speed of light, c, is constant. By decreasing the wavelength, you can increase the frequency.
by stephaniekim2K
Fri Oct 11, 2019 3:53 pm
Forum: Properties of Light
Topic: Converting units
Replies: 8
Views: 40

Re: Converting units

400nm (1m / 10^9nm) (1 A / 10^-10m) = 4000 A
by stephaniekim2K
Sat Oct 05, 2019 7:51 pm
Forum: Significant Figures
Topic: Sig Figs in Mulitstep Problems
Replies: 10
Views: 77

Re: Sig Figs in Mulitstep Problems

Personally, I have a calculator that keeps track of all the problems I did previously (TI-84), so what I do is when I am doing work on paper, I will write the answer (throughout the problem not the final answer) with the amount of sig figs that are called for, but when I am calculating the next port...
by stephaniekim2K
Sat Oct 05, 2019 7:42 pm
Forum: Balancing Chemical Reactions
Topic: Strategies for Balancing Chemical Equations
Replies: 12
Views: 89

Re: Strategies for Balancing Chemical Equations

It might also help to examine the full equation and start with the elemnts or molecules taht appear the least amount of times on each side and work your way up. I agree that this is one of the easiest ways for me to balance equations. Professor Lavelle did also mention this method as his way of bal...
by stephaniekim2K
Sat Oct 05, 2019 7:40 pm
Forum: Balancing Chemical Reactions
Topic: When are atoms lost or created?
Replies: 14
Views: 213

Re: When are atoms lost or created?

Atoms cannot be created or destroyed according to the Law of Conservation in chemical reactions, but Professor Lavelle did mention that in the future we will learn about a different type of reaction where atoms can be created of destroyed.
by stephaniekim2K
Sat Oct 05, 2019 7:36 pm
Forum: Limiting Reactant Calculations
Topic: Order of atoms in molecules
Replies: 6
Views: 60

Re: Order of atoms in molecules

Like most people said already, the order is not very important, but there is a method called the Hill System that states that Carbon atoms are listed first, then Hydrogen, and the rest of the atoms alphabetically.
by stephaniekim2K
Sat Oct 05, 2019 7:30 pm
Forum: Limiting Reactant Calculations
Topic: Percent or theoretical yield
Replies: 14
Views: 150

Re: Percent or theoretical yield

Theoretical yield is the calculated amount of yield you get when you plug in values into an equation. Percent yield, however, is the percentage of how much actual yield is produced out of the theoretical yield. Factors that inhibit reactions from producing 100% yield occur because of loss of product...

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