## Search found 54 matches

Sun Feb 23, 2020 11:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work
Replies: 14
Views: 279

### Re: Work

Work done on the system is positive. Work done by a system is negative.
Sun Feb 23, 2020 11:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Kelvin or Celsius?
Replies: 47
Views: 974

### Re: Kelvin or Celsius?

Should use Kelvin so the units match the constant.
Sun Feb 23, 2020 11:28 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: U vs H
Replies: 15
Views: 271

### Re: U vs H

Delta U is the change in internal energy while delta H is the change in enthalpy.
Sun Feb 23, 2020 11:21 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 13
Views: 248

### Re: Reversible vs Irreversible

For a system to be considered reversible, delta S must equal 0.
Sun Feb 23, 2020 11:19 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive vs. Extensive
Replies: 15
Views: 323

### Re: Intensive vs. Extensive

Extensive properties depend on mass and intensive properties do not.
Wed Feb 05, 2020 10:36 am
Forum: Phase Changes & Related Calculations
Topic: Heating Curve
Replies: 6
Views: 74

### Re: Heating Curve

flat areas of the graph are where phase changes are occurring. At these instances temperature is constant because all energy is being used to change phases.
Wed Feb 05, 2020 10:33 am
Forum: Ideal Gases
Topic: Temperature
Replies: 17
Views: 154

### Re: Temperature

If the question asks for the change in temperature you can use either. If not, you need to look at what units are used in the question or which units are used in the constants.
Wed Feb 05, 2020 10:29 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Shifts
Replies: 6
Views: 134

### Re: Shifts

It depends on the circumstance but in general, the reaction will shift in the direction that allows for it to reach equilibrium. For example, if Q (reaction quotient)<K(equilibrium constant) the reaction will shift to the right because the concentration of reactants is greater than the concentration...
Wed Feb 05, 2020 10:27 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reaction Direction
Replies: 14
Views: 255

### Re: Reaction Direction

I know that K represents the equilibrium constant, but what does Q represent in this situation? In this situation, Q would represent the state of the reaction at a point where equilibrium has not been reached yet. This is why they are asking about which direction the reaction will occur ("left...
Wed Feb 05, 2020 10:23 am
Forum: Ideal Gases
Topic: Ideal gas constant
Replies: 4
Views: 64

### Re: Ideal gas constant

You need to use the constant that has the same units as the values given in the question as you need units to cancel out.
Sun Feb 02, 2020 3:58 pm
Forum: Phase Changes & Related Calculations
Topic: Internal Energy, U
Replies: 6
Views: 72

### Re: Internal Energy, U

Only when change in pressure and change in volume are zero.
Sun Feb 02, 2020 3:57 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 17
Views: 141

### Re: Phase Changes

While a phase change is occurring the temperature is constant, but once the phase change is complete the temperature will continue to change.
Sun Feb 02, 2020 3:53 pm
Forum: Phase Changes & Related Calculations
Topic: Calorimeters
Replies: 8
Views: 57

### Calorimeters

Does the type of calorimeter affect the problem at all? Or do the equations work the same regardless of the type of calorimeter?
Sun Feb 02, 2020 3:51 pm
Forum: Phase Changes & Related Calculations
Topic: Open vs Isolated System
Replies: 15
Views: 641

### Re: Open vs Isolated System

Energy can be transferred in a closed system while in an isolated system energy can't be transferred.
Sun Feb 02, 2020 3:48 pm
Forum: Phase Changes & Related Calculations
Topic: Calorimeter
Replies: 8
Views: 100

### Re: Calorimeter

A bomb calorimeter is able to withstand more pressure and is more precise.
Sun Jan 26, 2020 11:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Gas Constant
Replies: 13
Views: 82

### Re: Gas Constant

The constants will be given on the formula sheet during the exams.
Sun Jan 26, 2020 11:26 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 251

### Re: ICE BOX

If any of the K values are smaller than 10^-3 then they are considered negligible.
Sun Jan 26, 2020 11:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp to Kc
Replies: 11
Views: 82

### Re: Kp to Kc

Liquid water is not included in equilibrium concentration calculations.
Sun Jan 26, 2020 11:23 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 43
Views: 517

### Re: Kc vs Kp

Kp is for gases and uses partial pressure. Kc uses concentrations.
Sun Jan 26, 2020 11:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE
Replies: 20
Views: 173

### Re: ICE

ICE is used when trying to the find the equilibrium concentrations.
Sun Jan 19, 2020 10:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE Tables
Replies: 13
Views: 96

### Re: ICE Tables

H20 is not included when it is in liquid form.
Sun Jan 19, 2020 10:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for Gases
Replies: 12
Views: 96

### Re: K for Gases

You would use Kp because you would use pressure to find the equilibrium constant of gases.
Sun Jan 19, 2020 10:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs Q
Replies: 14
Views: 85

### Re: K vs Q

K is a constant and is used when a reaction is in equilibrium. Q can be found at any point during a reaction and can be compared to K in order to find the direction of the reaction.
Sun Jan 19, 2020 10:14 pm
Forum: Ideal Gases
Topic: ICE Tables
Replies: 8
Views: 102

### Re: ICE Tables

It depends on whether the reaction is going forward or reverse. This is found by comparing the reaction quotient (Q) and the chemical equilibrium (K).
Sun Jan 19, 2020 10:11 pm
Forum: Ideal Gases
Topic: homework #3
Replies: 16
Views: 213

### Re: homework #3

Anything learned during the week should be the focus of the homework. Homework 3 should probably be on acid and base equilibria.
Sat Jan 11, 2020 3:14 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: HW 5J.5
Replies: 8
Views: 58

### Re: HW 5J.5

You would only use reactants and products that are in gas or aqueous phases when calculating the equilibrium constant.
Sat Jan 11, 2020 3:10 pm
Forum: Ideal Gases
Topic: R in PV=nRT
Replies: 34
Views: 683

### Re: R in PV=nRT

R is the gas constant with a value of 8.314 (J)/((Mol)(K))
Sat Jan 11, 2020 3:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q
Replies: 10
Views: 90

### Re: Q

Q, the reactant quotient, is calculated the same way as K, but Q is not in equilibrium.
Sat Jan 11, 2020 3:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 3
Views: 39

### Re: 5I.13

Since the equation involves gases you would need to use Kp and partial pressures.
Wed Jan 08, 2020 10:20 pm
Forum: Ideal Gases
Topic: Understanding Q
Replies: 13
Views: 109

### Re: Understanding Q

When solving for Q you would leave out solids and liquids.
Sat Dec 07, 2019 7:16 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH Calculation
Replies: 3
Views: 56

### Re: pH Calculation

Since HCL is a strong acid, pH can be found by taking -log[HCL].
Sat Dec 07, 2019 7:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Disobeying the octect rule
Replies: 4
Views: 148

### Re: Disobeying the octect rule

elements with room in their d-orbitals usually can disobey the octet rule.
Sat Dec 07, 2019 7:04 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: when to use what equation
Replies: 5
Views: 63

### Re: when to use what equation

Also, 10^-ph gives you the H+ concentration.
Sat Dec 07, 2019 3:00 pm
Forum: Ionic & Covalent Bonds
Topic: hydrogen
Replies: 5
Views: 138

### Re: hydrogen

The Hydrogen must be bound to an F, O, or N.
Sat Dec 07, 2019 2:58 pm
Forum: Significant Figures
Topic: pH sig figs
Replies: 9
Views: 223

### Re: pH sig figs

I think you would use the same rules so your answer should match the lowest number of significant figures that were given in the question.
Sat Dec 07, 2019 2:22 pm
Forum: Conjugate Acids & Bases
Topic: studying
Replies: 5
Views: 171

### Re: studying

Should probably prioritize strong acids and bases but also work on the problems posted in the syllabus.
Sat Dec 07, 2019 2:21 pm
Forum: Bronsted Acids & Bases
Topic: Main Difference
Replies: 4
Views: 137

### Re: Main Difference

Bronsted acids and bases accept or donate protons while Lewis acids and bases accept or donate electron pairs.
Sat Dec 07, 2019 2:18 pm
Forum: Lewis Acids & Bases
Topic: Lewis acid
Replies: 3
Views: 113

### Re: Lewis acid

Since NH4 has a full octet and doesn't want to accept any more electrons, it isn't considered a Lewis acid.
Sat Dec 07, 2019 2:15 pm
Forum: Lewis Acids & Bases
Topic: Water
Replies: 8
Views: 180

### Re: Water

Water can act as either an acid or a base.
Sat Dec 07, 2019 2:14 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: 6B.5
Replies: 2
Views: 119

### Re: 6B.5

Osvaldo Sanchez Fernandez -4F wrote:You can start to approach this by simply knowing that the addition of pOH and pH Is equal to 14 so (pOH+pH=14). So if you find the pH of the molecule using the molarity you found in each problem you can just subtract it to 14 and get pOH or vice versa.

How do you solve for (c)?
Sat Dec 07, 2019 12:54 pm
Forum: Properties of Electrons
Topic: Mass of an electron
Replies: 9
Views: 338

### Re: Mass of an electron

The mass of an electron was provided on the formula sheet given out during midterm 1.
Sat Dec 07, 2019 12:54 pm
Forum: Properties of Light
Topic: 1b.
Replies: 1
Views: 110

### Re: 1b.

energy from the lamp = 32 J/s * 2s = 64J. Also 420nm should be converted to m (420 x 10^-9). Use the equation: E=hc/wavelength which gives you 4.73 x 10^-19 J per photon. Then 64/4.73 x 10^-19 gives you 1.4 x 10^20 J.
Sat Dec 07, 2019 12:47 pm
Forum: Significant Figures
Topic: Sig Figs on Tests
Replies: 24
Views: 1113

### Re: Sig Figs on Tests

Usually your answer should match the lowest amount of significant figures given in the question.
Sat Dec 07, 2019 12:45 pm
Forum: Significant Figures
Topic: Sig Figs on Midterm Q4 Part 2
Replies: 3
Views: 150

### Re: Sig Figs on Midterm Q4 Part 2

You would use the lowest amount of sig figs present in the problem which is 3 because of the 100 kJ
Sun Nov 24, 2019 11:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE Format
Replies: 34
Views: 280

### Re: AXE Format

The 1 is unnecessary.
Sun Nov 24, 2019 11:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 7
Views: 107

### Bond Angles

Why can bond angles be slightly smaller than a given value? For example, why are some bond angles "slightly smaller" than 109.5?
Sun Nov 24, 2019 11:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs on Cenrtral Atom
Replies: 11
Views: 129

### Re: Lone Pairs on Cenrtral Atom

Lone pairs repel other bonds and therefore cause the bond angles to decrease.
Sun Nov 24, 2019 11:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shape
Replies: 21
Views: 384

### Re: T-shape

AX3E2 would be a T-shape with bond angles of 90 and 180.
Sun Nov 24, 2019 11:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Final
Replies: 10
Views: 110

### Re: Final

Yes, the final is cumulative.
Sun Nov 17, 2019 8:56 pm
Forum: Ionic & Covalent Bonds
Topic: Character of Bonds
Replies: 7
Views: 93

### Re: Character of Bonds

Maddie wrote:Will he give us the actual electronegativity values on the tests though?

Using trends, you need to know the electronegativity of atoms relative to other atoms.
Sun Nov 17, 2019 8:50 pm
Forum: Ionic & Covalent Bonds
Topic: Homework for Week 7
Replies: 2
Views: 50

### Re: Homework for Week 7

I believe chemical bonds are part of the second test so yes, you can turn in work on chemical bonds.
Sun Nov 17, 2019 7:32 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonds
Replies: 6
Views: 74

### Re: Hydrogen Bonds

Hydrogen bonding occurs when a hydrogen atom is covalently bound to an oxygen, fluorine, or nitrogen atom.
Sun Nov 17, 2019 7:29 pm
Forum: Ionic & Covalent Bonds
Topic: London Dispersion
Replies: 13
Views: 147

### Re: London Dispersion

Anokhi Patel 4G wrote:what exactly is london dispersion?

LDF is the weakest of the intermolecular forces. LDF occurs when electrons in two adjacent atoms form temporary dipoles.
Sun Nov 17, 2019 7:19 pm
Forum: Ionic & Covalent Bonds
Topic: Dipole-Dipole Interactions
Replies: 3
Views: 41

### Dipole-Dipole Interactions

What type of molecules contain dipole-dipole interactions?