## Search found 49 matches

Tue Feb 19, 2019 4:59 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4I.9
Replies: 2
Views: 170

### 4I.9

9.47 Initially a sample of ideal gas at 323 K occupies 1.67 L at 4.95 atm. The gas is allowed to expand to 7.33 L by two pathways: (a) isothermal, reversible expansion; (b) isothermal, irreversible free expansion. Calculate Stot, S, and Ssurr for each pathway I dont understand how to solve part B. a...
Tue Feb 19, 2019 3:10 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: irreversible v reversible
Replies: 4
Views: 367

### irreversible v reversible

Why does S total increase with irreversible but not reversible?
Sun Feb 17, 2019 5:39 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4F17
Replies: 1
Views: 261

### 4F17

How do you calculate the standard entropy of vaporization of water at 85C, given that its standard entropy of vaporization at 100C is 109.0 J/K/mol and the molar heat capacities at constant pressure of liquid water and water vapor are 75.3 J/K/mol and 33.6 J/K/mol? For this problem, I used change in...
Wed Feb 13, 2019 2:30 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4.11
Replies: 1
Views: 88

### 4.11

During the test of an internal combustion engine, 3.00L of nitrogen gas at 18.5 degrees C was compressed suddenly (and irreversibly) to .500L by driving in a piston. In the process the temperature of the gas increased to 28.1 degrees C. Assume ideal behavior and 1.00 mole of nitrogen gas. What is th...
Wed Feb 13, 2019 1:47 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4F.1
Replies: 2
Views: 331

### 4F.1

A human body generates heat at the rate of about 100. W (1 W 1 J .s-'). (a)At what rate does your body heat generate entropy in your surroundings, taken to be at 20.0 C? (b)How much entropy do you generate each day? (c)Would the entropy generated be greater or less if you were in a room kept at 30° ...
Wed Feb 13, 2019 12:05 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: calorimeters
Replies: 1
Views: 89

### calorimeters

which equation do u use for bomb calorimeters and which one do u use for normal calorimeters?
Wed Feb 13, 2019 12:00 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: units
Replies: 7
Views: 461

### units

what are the units for PV=nRT?
Tue Feb 12, 2019 5:06 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: units
Replies: 2
Views: 127

### units

is q always written as J and delta U and delta H always written as J/mol? (unless its specific aka over g)
Tue Feb 12, 2019 3:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: the relation b/t change in H and change in U
Replies: 1
Views: 105

### the relation b/t change in H and change in U

the textbook states that reaction enthalpy is less negative than the reaction internal energy for reactions that generate gases. Why is this?
Tue Feb 12, 2019 3:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy and internal energy
Replies: 1
Views: 95

### enthalpy and internal energy

what is the conceptual difference of enthalpy and internal energy?
Mon Feb 11, 2019 10:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 2 molar heat capacities of ideal gas
Replies: 1
Views: 114

### 2 molar heat capacities of ideal gas

Can someone explain to me why the heat capacities for gas at a constant pressure are higher than that at constant volume? Thank you!
Mon Feb 11, 2019 7:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy
Replies: 2
Views: 121

### enthalpy

Can someone just conceptually explain what enthalpy is? I still dont quite get it because according to the textbook, enthalpy is a state function that keeps track of losses of energy as expansion work during heat transfer at constant pressure. So I would think enthalpy as something to do with work. ...
Mon Feb 11, 2019 2:21 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: equipartition theorem
Replies: 1
Views: 259

### equipartition theorem

Do we need to know the equipartition theorem from the textbook in chapter 4B.3? if so, can someone explain this to me? I don't understand it. Thanks!
Mon Feb 11, 2019 1:24 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: state functions
Replies: 2
Views: 140

### state functions

can someone explain to me why heat is not a state function? I read the textbook but i still dont get it. Thanks!
Sun Feb 10, 2019 9:09 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bomb calorimeter
Replies: 1
Views: 113

### Bomb calorimeter

whats the difference between a bomb calorimeter and a normal one and how does this affect calculations?
Thu Jan 24, 2019 11:04 am
Forum: Amphoteric Compounds
Topic: amphoteric v amphiprotic
Replies: 5
Views: 524

### amphoteric v amphiprotic

whats the difference between the two?
Thu Jan 24, 2019 9:36 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.3
Replies: 1
Views: 314

### 6B.3

A careless laboratory technician wants to prepare 200.0 mL of a 0.025 HCl (aq) solution but uses a volumetric flask of volume 250.0 mL by mistake. (a) what would the pH of the desired solution have been? (b) What will be the actual pH of the solution as prepared?
Wed Jan 23, 2019 11:49 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: help on last module!
Replies: 2
Views: 129

### help on last module!

The photosynthesis reaction, 6 CO2(g) + 6 H2O(l) ⇌ C6H12O6(aq) + 6 O2(g), is endothermic. What effect will the following changes have on the equilibrium composition. a) Water is added. b) The partial pressure of CO2 is decreased. A. a) Decrease [C6H12O6] and [O2], b) Decrease [O2] B. a) Decrease [C6...
Wed Jan 16, 2019 5:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: partial pressure v concentration
Replies: 4
Views: 130

### partial pressure v concentration

If we have a reaction that includes both gas and aqueous states, do we use partial pressure or concentration?
Fri Jan 11, 2019 12:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: liquids in equilibrium
Replies: 2
Views: 107

### liquids in equilibrium

I'm still confused on why liquids are not included in calculating K while aqueous solutions are. Can someone explain this to me? Thanks!
Sun Dec 09, 2018 10:12 am
Forum: Dipole Moments
Topic: Why is CH2Cl2 polar while CH4 is not?
Replies: 2
Views: 949

### Re: Why is CH2Cl2 polar while CH4 is not?

Its because Cl is more electroneg than C and in CH4, everything is shared pretty evenly
Sun Dec 09, 2018 10:11 am
Forum: Dipole Moments
Topic: Cis vs trans
Replies: 4
Views: 416

### Re: Cis vs trans

In that case, I would think that whether the molecule is cis or trans will be given
Sun Dec 09, 2018 10:09 am
Forum: Dipole Moments
Topic: Dipole Moment/Polarity
Replies: 2
Views: 320

### Re: Dipole Moment/Polarity

a dipole moment happens when there are different charges between atoms. This can happen if one is more electronegative or maybe has a lone pair while the other doesn't. You can look at the shape of the molecule and how the atoms arrange themselves around the central atom to see if the molecule would...
Sun Dec 09, 2018 10:06 am
Forum: Dipole Moments
Topic: Forces Present in molecules
Replies: 3
Views: 336

### Re: Forces Present in molecules

van der waals happens everywhere, dipole dipole would happen if there are multiple polar molecules, and dipole induced dipole can occur with one polar and one nonpolar
Sun Dec 09, 2018 10:04 am
Forum: Dipole Moments
Topic: Identifying Dipole-Dipole
Replies: 2
Views: 353

### Re: Identifying Dipole-Dipole

it would be in between two polar molecules
Sun Dec 09, 2018 10:03 am
Forum: Air Pollution & Acid Rain
Topic: Basic Rain
Replies: 5
Views: 418

### Re: Basic Rain

Its probably possible on a different planet but since our atmosphere has a lot of CO2, probably not on earth.
Sun Dec 09, 2018 10:01 am
Forum: Calculating the pH of Salt Solutions
Topic: pH formula?
Replies: 21
Views: 737

### Re: pH formula?

@305127455 wait shouldnt pOH be 14-(-log[H+]) ?
Sun Dec 09, 2018 9:57 am
Forum: Calculating the pH of Salt Solutions
Topic: konstant?
Replies: 5
Views: 267

### konstant?

What does the concentration constant symbolize?
Sat Dec 08, 2018 11:39 pm
Forum: Bronsted Acids & Bases
Topic: 7th edition fundamentals J.9
Replies: 1
Views: 87

### 7th edition fundamentals J.9

identify the salt that is produced from a neutralization reaction between ammonia and phosphoric acid.
Can someone explain how to do this? Thanks!
Sat Dec 08, 2018 11:05 pm
Forum: Bronsted Acids & Bases
Topic: 7th edition fundamentals J.9
Replies: 1
Views: 318

### 7th edition fundamentals J.9

Identify the salt that is produced from the acid base neutralization reaction between sodium hydroxide and propanoic acid CH3CH2COOH
Sat Dec 08, 2018 5:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 7th edition 9C.5
Replies: 1
Views: 110

### 7th edition 9C.5

is HN(CH2CH2NH2)2 polydentate and why? If so, what is the maximum amount of places this ligand can bind simultaneously to a metal ion?
Sat Dec 08, 2018 4:25 pm
Forum: Naming
Topic: metal ions
Replies: 1
Views: 87

### metal ions

which metal ions do we need to remember the special names of when naming coor. compounds? Thanks!
Sat Nov 10, 2018 5:03 pm
Forum: Dipole Moments
Topic: induced-dipole
Replies: 2
Views: 147

### Re: induced-dipole

there might a difference but if there is, it's very slight. In Mr. Lavelle's lecture, he said both have the strength of about -2 KJ/mol
Thu Nov 01, 2018 3:18 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Key Words
Replies: 4
Views: 192

### Re: Key Words

I think the words in bold from the textbook chapter might be good to know. Such as shielded, effective nuclear charge, penetrate, electron configuration, the pauli exclusion principle, paired, closed shell, core, valence electrons, parallel spins, the building-up principle, hund's rule, excited stat...
Thu Nov 01, 2018 3:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Losing Electrons
Replies: 2
Views: 126

### Re: Losing Electrons

4p because it has more energy than 3d as seen by their n.
Thu Nov 01, 2018 3:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: S and d orbitals order in configuration
Replies: 2
Views: 157

### Re: S and d orbitals order in configuration

yup! I think youre on the right track that whatever has the lower n comes first, hence d usually ends up before s when its written out because of the fact that d is usually n-1 if the energy lv of s is n.
Thu Nov 01, 2018 3:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.25
Replies: 1
Views: 96

### 1E.25

Give the notation for the valence-shell configuration (including the outermost d-electrons) of (a) the alkali metals; (b) Group 15 elements; (c) group 5 transition metals; (d) the "coinage" metals (Cu, Ag, Au).

Thanks!
Mon Oct 29, 2018 10:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.13
Replies: 3
Views: 157

### 1E.13

I'm a bit confused on how to write the e- configuration of silver. I would think it's [Kr] 4d^9 5s^2 but according to the back of the 7th edition textbook, the answer is [Kr] 4d^10 5s^1. I'm noticing that this is kind of like the exceptions of copper and chromium mentioned in class, is this an excep...
Sun Oct 21, 2018 12:48 am
Forum: DeBroglie Equation
Topic: de broglie post module q 35 [ENDORSED]
Replies: 2
Views: 105

### de broglie post module q 35[ENDORSED]

Calculate the wavelength of a 275 kg single-seat electric car traveling at a speed of 125 km.hr-1. Do electric cars have wavelike properties?
Sun Oct 21, 2018 12:47 am
Forum: DeBroglie Equation
Topic: de broglie post module q 34 [ENDORSED]
Replies: 1
Views: 84

### de broglie post module q 34[ENDORSED]

If an electron (mass 9.11 x 10-31 kg) has an associated wavelength of 7.28 x 10-9 m, what is its speed? Is your answer reasonable, why?
Fri Oct 19, 2018 3:10 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: H-Atom and multi-electron atoms
Replies: 3
Views: 123

### Re: H-Atom and multi-electron atoms

yup. Each atom has it's own unique emission line spectrum and the equation was made specifically for hydrogen through finding the its line first and then coming up with an equation that made sense based on experimental data. Not to mention that multiple electrons complicates things a lot because ele...
Fri Oct 19, 2018 3:04 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation
Replies: 4
Views: 218

### Re: Rydberg equation

It applies specifically to hydrogen atoms only and tells us how much energy is needed to bring an electron from the energy state n to the next lower energy state.
Fri Oct 19, 2018 3:01 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lyman vs Balmer
Replies: 6
Views: 325

### Re: Lyman vs Balmer

All that they are referring to is a series of wavelengths discovered that are able to be absorbed (and emitted) by a hydrogen atom. Lyman discovered a series of wavelengths that can be absorbed by a hydrogen atom in the UV light range, hence these series of wavelengths are called the Lyman series wh...
Fri Oct 19, 2018 2:57 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer and Lyman Series
Replies: 2
Views: 96

### Re: Balmer and Lyman Series

All that they are referring to is a series of wavelengths discovered that are able to be absorbed (and emitted) by a hydrogen atom. Lyman discovered a series of wavelengths that can be absorbed by a hydrogen atom in the UV light range, hence these series of wavelengths are called the Lyman series wh...
Fri Oct 19, 2018 2:53 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Module #41
Replies: 3
Views: 128

### Re: Atomic Spectra Module #41

#41 states For the hydrogen atom which statement is true? A. The transition from n = 5 to n = 3 involves greater energy than one from n = 4 to n = 2. This is false because, as elections reach higher and higher energy states, the energy gap between each state gets smaller and smaller. Therefore, even...
Fri Oct 19, 2018 2:44 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr condition explaining lines
Replies: 2
Views: 141

### Re: Bohr condition explaining lines

The bohr frequency condition states that the energy of the photon must match the energy needed to bring an electron to a higher energy state exactly in order to be absorbed, so the wavelengths shown on the spectrums just show which ones fit this condition because certain wavelengths correspond to sp...
Fri Oct 19, 2018 2:40 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Emission Spectrum and Atomic Spectrum
Replies: 2
Views: 114

### Re: Emission Spectrum and Atomic Spectrum

not sure if this is completely correct, but i think that this is because light being emitted and light being reflected are two different things. The light that is reflected is simply never absorbed and just bounces back because it doesn't match the energy required to bring the electron to a higher l...
Fri Oct 19, 2018 2:34 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Absorption Spectroscopy versus Atomic Emission Spectroscopy
Replies: 3
Views: 142

### Re: Atomic Absorption Spectroscopy versus Atomic Emission Spectroscopy

Since the experiment is detecting absorbed light not emitted light, its just called absorption line spectrum. It shows what wavelengths are absorbed not which ones are emitted.
Fri Oct 19, 2018 2:29 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation
Replies: 2
Views: 132

### Re: Rydberg equation

It's because the E in the Rydberg equation is measuring the amount of energy released when the electron jumps down to a lower energy level. The electron is losing energy, hence the negative value.