Search found 60 matches
- Thu Mar 14, 2019 9:19 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Calculating Entropy with Change in Temperature
- Replies: 1
- Views: 510
Calculating Entropy with Change in Temperature
Calculate the change in entropy when the pressure of 5.75g of helium gas is decreased from 320kPa to 40kPa while the temperature decreases from 423K to 273K. Assume idea behavior. I know that you should use two equations: deltaS=nRln(P1/P2) and deltaS=nCvln(T2/T1). Why would you use Cv and how would...
- Thu Mar 14, 2019 9:10 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate of Formation
- Replies: 1
- Views: 262
Rate of Formation
What is the difference between the rate law for formation of product and the experimental rate law? Would you solve for the rate law the same way for both?
- Thu Mar 14, 2019 9:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 24595
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
On Worksheet 9, how would you solve for #7?
- Mon Mar 11, 2019 12:01 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagram
- Replies: 3
- Views: 382
Cell Diagram
Do you include H+ in a cell diagram? Do you include all the products and reactants in a cell diagram except electrons?
- Sun Mar 10, 2019 11:59 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Potential
- Replies: 2
- Views: 309
Cell Potential
How would you find the largest cell potential if assembled in an electrochemical cell?
- Sun Mar 10, 2019 11:56 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous Reaction
- Replies: 5
- Views: 786
Spontaneous Reaction
Why would the precipitation of snowflakes inside a cloud at -10C and 0.839 atm be a spontaneous reaction?
- Fri Mar 01, 2019 12:54 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Significant Figures
- Replies: 2
- Views: 322
Significant Figures
When solving for deltaG, do you take into account the significant figures for temperature too?
- Fri Mar 01, 2019 12:52 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation State
- Replies: 4
- Views: 568
Oxidation State
Is there a way to quickly find which compound is reduced or oxidized in a reaction without having to calculate each oxidation state for each element?
- Fri Mar 01, 2019 12:48 pm
- Forum: Balancing Redox Reactions
- Topic: Test #2
- Replies: 10
- Views: 1142
Re: Test #2
If you see the standard reduction potential chart, the one with the higher (more positive) cell potential will be a stronger oxidizing agent while the one with the more negative cell potential will be a stronger reducing agent.
- Mon Feb 25, 2019 12:53 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Standard reaction Gibbs free energy
- Replies: 1
- Views: 288
Standard reaction Gibbs free energy
What is the different between standard reaction Gibbs free energy and and Gibbs free energy? How do we know when to use the standard cell potential for the equation for standard reaction Gibbs free energy?
- Mon Feb 25, 2019 12:46 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy and equilibrium concentration
- Replies: 2
- Views: 289
Gibbs Free Energy and equilibrium concentration
Reaction 1: Fructose-6-phosphate +ATP --> Fructose-1,6-biphosphate + ADP deltaG = -13.7 kJ/mol Reaction 2: Fructose-6-phosphate + HPO4 2- --> Fructose-1,6-biphosphate +H20 deltaG = 16.5 kJ/mol Question: If the concentration of ATP is adjusted to four times its equilibrium concentration, what is the ...
- Mon Feb 25, 2019 12:43 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy
- Replies: 1
- Views: 497
Gibbs Free Energy
Reaction 1: Fructose-6-phosphate +ATP --> Fructose-1,6-biphosphate + ADP deltaG = -13.7 kJ/mol Reaction 2: Fructose-6-phosphate + HPO4 2- --> Fructose-1,6-biphosphate +H20 deltaG = 16.5 kJ/mol To find the standard Gibb's free energy for ATP hydrolysis, my TA multiplied the Gibbs free energy of the f...
- Sun Feb 17, 2019 9:18 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy with Temperature and Volume
- Replies: 2
- Views: 1467
Entropy with Temperature and Volume
In a problem, if two initial and final values of temperature and volume are given in a problem in which two substances are mixed. Why would you need to solve for change in entropy using two equations (one with temperature and the other with volume) and add them together?
- Sun Feb 17, 2019 9:12 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous Reaction
- Replies: 1
- Views: 275
Spontaneous Reaction
When enthalpy change and entropy change are negative, why does the spontaneity depend on temperature?
- Sun Feb 17, 2019 9:09 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Nonexpansion Work
- Replies: 2
- Views: 375
Nonexpansion Work
In the textbook, it states that Gibbs Free Energy tells us how much nonexpansion work we can get from the system. What does it mean by nonexpansion work?
- Sun Feb 10, 2019 5:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of Formation and Reaction
- Replies: 1
- Views: 320
Enthalpy of Formation and Reaction
When is the enthalpy of formation equal to the enthalpy of the reaction? Is it only when one mole of a product is produced?
- Sun Feb 10, 2019 5:07 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of Formation Reaction
- Replies: 1
- Views: 377
Enthalpy of Formation Reaction
In the equation: 2Al (s) + 6HCl (g) ---> 2AlCl3 (s) + 3H2 (g), the enthalpy of formation for AlCl3 is given as -704kJ/mol. The enthalpy of the reaction is given as well as -856 kJ/mol. To find the enthalpy of formation of gaseous hydrochloric acid, I know I would have to do the sum of the enthalpy o...
- Sun Feb 10, 2019 5:01 pm
- Forum: Phase Changes & Related Calculations
- Topic: Change In Internal Energy
- Replies: 1
- Views: 276
Change In Internal Energy
How do you know when the change in internal energy is equal to 0? Does it depend on if the system is open, closed, or isolated?
- Tue Jan 29, 2019 6:30 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Applied Exercises 8.111
- Replies: 1
- Views: 223
Applied Exercises 8.111
Crude petroleum is often contaminated by poisonous hydrogen sulfide gas. The Claus process for the extraction of sulfur from petroleum has two steps: 2 H2S(g) + 3 O2(g) ---> 2 SO2(g) + 2 H2O(l) 2 H2S(g) + SO2(g) ---> 3 S(s) + 2 H2O(l) How would you write a thermochemical equation for the overall rea...
- Tue Jan 29, 2019 6:26 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Applied Exercises 8.113
- Replies: 1
- Views: 283
Applied Exercises 8.113
Water gas is an inexpensive, low-grade fuel that can be made from coal. (a) Is the production of water gas exothermic or endothermic? How would you know? The reaction is C(s) + H2O(g) ---> CO(g) + H2(g) (b) How would you calculate the enthalpy change for the production of 200. L of hydrogen at 500. ...
- Tue Jan 29, 2019 6:23 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Applied Exercises 8.115
- Replies: 1
- Views: 253
Applied Exercises 8.115
An experimental automobile burns hydrogen for fuel. At the beginning of a test drive, the rigid 30.0-L tank was filled with hydrogen at 16.0 atm and 298 K. At the end of the drive, the temperature of the tank was still 298 K, but its pressure was 4.0 atm. (a) How many moles of H2 were burned during ...
- Sun Jan 20, 2019 10:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Applied Exercises 12.131
- Replies: 1
- Views: 295
Applied Exercises 12.131
In the tissues the equilibrium H3O+ (aq) + HbO2- (aq) Δ HHb(aq) + H2O(l) + O2(aq) releases oxygen. When muscles work hard, they produce lactic acid as a by-product. (a) What effect will the lactic acid have on the concentration of HbO2- ? (b) When the hemoglobin returns to the lungs, where oxygen co...
- Sun Jan 20, 2019 10:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Integrated Exercises 12.109
- Replies: 1
- Views: 192
Integrated Exercises 12.109
Hydronium and hydroxide ions appear to move through water much faster than other kinds of ions. What explanation can you make from this observation? What does this mean?
- Sun Jan 20, 2019 10:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Polyprotic Acids and Bases 12.81
- Replies: 1
- Views: 279
Polyprotic Acids and Bases 12.81
What is the pH of each of the following diprotic acid solutions at 25 C: (a) 0.010 M H2CO3(aq);
(b) 0.10 M (COOH)2(aq); (c) 0.20 M H2S(aq)?
(b) 0.10 M (COOH)2(aq); (c) 0.20 M H2S(aq)?
- Sun Jan 20, 2019 10:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Polyprotic Acids and Bases 12.79
- Replies: 2
- Views: 363
Polyprotic Acids and Bases 12.79
How would you calculate the pH of 0.15 M H2SO4(aq) at 25 C?
- Sun Jan 20, 2019 10:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: The pH of Solutions of Weak Acids and Bases 12.73
- Replies: 1
- Views: 491
The pH of Solutions of Weak Acids and Bases 12.73
If a 15.5-g sample of CH3NH3Cl is dissolved in water to make 450. mL of solution, how would you find the pH of the solution?
- Sun Jan 20, 2019 10:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong vs Weak Acids and Bases
- Replies: 2
- Views: 224
Strong vs Weak Acids and Bases
How can you tell if an acid or base is strong or weak?
- Thu Jan 10, 2019 1:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: The Response of Equilibria to Changes in Conditions 11.79
- Replies: 1
- Views: 95
The Response of Equilibria to Changes in Conditions 11.79
A reactor for the production of ammonia by the Haber process is found to be at equilibrium with PN2 = 3.11 bar, PH2 = 1.64 bar, and PNH3 = 23.72 bar. If the partial pressure of N2 is increased by 1.57 bar, how would you find the partial pressure of each gas once equilibrium is re-established?
- Thu Jan 10, 2019 1:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: The Response of Equilibria to Changes in Conditions 11.81
- Replies: 1
- Views: 140
The Response of Equilibria to Changes in Conditions 11.81
If N2(g) + 3 H2(g) --> 2 NH3(g), K = 1.7 x 10^-3 at 600. K and 7.8 x 10^-5 at 700. K, and a gaseous mixture consisting of 2.23 mmol N2 and 6.69 mmol H2 in a 500.-mL container was heated to 600. K and allowed to reach equilibrium. Will more ammonia be formed if that equilibrium mixture is then heated...
- Thu Jan 10, 2019 1:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Integrated Exercises 11.91
- Replies: 1
- Views: 137
Integrated Exercises 11.91
At 500C, Kc = 0.061 for N2(g) + 3 H2(g) --> 2 NH3(g). If analysis shows that the composition of the reaction mixture at 500C is 3.00 mol*L^-1 N2, 2.00 mol*L^-1 H2, and 0.500 mol*L^-1 NH3, is the reaction at equilibrium? If not, in which direction does the reaction tend to proceed to reach equilibrium?
- Wed Dec 05, 2018 12:59 am
- Forum: Lewis Acids & Bases
- Topic: Identifying the acid and base
- Replies: 3
- Views: 470
Identifying the acid and base
What is the acid and base in these reactions?
a. CH3NH2 (aq) + H30+ (aq) ---> CH3NH3+ (aq) + H20 (l)
b. CH3NH2 (aq) + CH3COOH (aq) ---> CH3NH3+ (aq) + CH3CO2- (aq)
c. 2 HI (aq) + Ca0 (s) ---> CaI2 (aq) + H20 (l)
a. CH3NH2 (aq) + H30+ (aq) ---> CH3NH3+ (aq) + H20 (l)
b. CH3NH2 (aq) + CH3COOH (aq) ---> CH3NH3+ (aq) + CH3CO2- (aq)
c. 2 HI (aq) + Ca0 (s) ---> CaI2 (aq) + H20 (l)
- Wed Dec 05, 2018 12:54 am
- Forum: Identifying Acidic & Basic Salts
- Topic: Proton Transfer Reaction
- Replies: 1
- Views: 230
Proton Transfer Reaction
How would you write a chemical reaction showing the proton transfer reaction of a cation or anion with water?
- Wed Dec 05, 2018 12:53 am
- Forum: Lewis Acids & Bases
- Topic: J.19
- Replies: 1
- Views: 216
J.19
How would you write the balanced chemical equations for the reaction of 1 mol of formula units of each acidic oxide with 1 mol of water molecules to form an oxoacid and name the acid formed: (a) CO2; (b) SO3?
- Sat Dec 01, 2018 4:19 pm
- Forum: Lewis Acids & Bases
- Topic: Weak Acids and Bases 12.51
- Replies: 2
- Views: 673
Weak Acids and Bases 12.51
Which acid in each of the following pairs is stronger and explain why: (a) HF or HCl; (b) HClO or HClO2; (c) HBrO2 or HClO2; (d) HClO4 or H3PO4; (e) HNO3 or HNO2; (f) H2CO3 or H2GeO3.
- Sat Dec 01, 2018 4:18 pm
- Forum: Lewis Acids & Bases
- Topic: Weak Acids and Bases 12.53
- Replies: 1
- Views: 296
Weak Acids and Bases 12.53
Why do these acids have different strengths? (a) acetic acid and trichloroacetic acid; (b) acetic acid and formic acid.
- Sat Dec 01, 2018 4:16 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: The pH of Solutions of Weak Acids and Bases 12.65
- Replies: 5
- Views: 642
The pH of Solutions of Weak Acids and Bases 12.65
How would you determine whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7. If pH<7 or pH>7, write a chemical equation to justify your answer. (a) NH4Br; (b) Na2CO3; (c) KF; (d) KBr; (e) AlCl3; (f) Cu(NO3)2.
- Sat Nov 24, 2018 7:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape 4.45
- Replies: 3
- Views: 1191
Molecular Shape 4.45
How would you describe the structure of the formaldehyde molecule, CH2O, in terms of hybrid orbitals, bond angles, and pi- and sigma-bonds. The C atom is the central atom to which the other three atoms are attached.
- Sat Nov 24, 2018 7:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HCH bond angles 4.73
- Replies: 2
- Views: 3114
HCH bond angles 4.73
For each of the following species: CH3 ; CH4; CH3 ; CH2; CH22 ; CH22, identify each as a radical or not. How would you rank them in order of increasing HCH bond angles?
- Sat Nov 24, 2018 7:20 pm
- Forum: Hybridization
- Topic: Hybridization 4.75
- Replies: 2
- Views: 1295
Hybridization 4.75
If an organic compound distilled from wood was found to have a molar mass of 32.04 g·mol^-1 and the following composition by mass: 37.5% C, 12.6% H, and 49.9% O. What are the bond angles about the carbon and oxygen atoms? What is the hybridization of the carbon and oxygen atoms? Is the molecule pola...
- Wed Nov 14, 2018 11:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape 4.91
- Replies: 1
- Views: 267
Molecular Shape 4.91
Why would the molecule Benzyne, C6H4 be highly reactive?
- Wed Nov 14, 2018 11:35 pm
- Forum: Hybridization
- Topic: Hybridization 4.95
- Replies: 1
- Views: 245
Hybridization 4.95
How would you identify the composition of the bonds in the bonding in CH2=CHCHO and the hybridization of each lone pair?
- Wed Nov 14, 2018 11:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Structure 4.111
- Replies: 2
- Views: 339
Molecular Structure 4.111
How would you describe the structure of the CH3CN molecule in terms of hybrid orbitals, bond angles, and sigma and pi bonds when the N atom is a terminal atom?
- Wed Nov 07, 2018 10:06 pm
- Forum: Lewis Structures
- Topic: Electron Pairs 3.61
- Replies: 2
- Views: 275
Electron Pairs 3.61
How many numbers of electron pairs (both bonding and lone pairs) are there on the iodine atom in (a) ICl2 ; (b) ICl4 ;(c) ICl3; (d) ICl5?
- Wed Nov 07, 2018 10:05 pm
- Forum: Lewis Structures
- Topic: Radicals 3.55
- Replies: 3
- Views: 368
Radicals 3.55
Which of the following species are radicals? (a) NO2 ;(b) CH ; (c) OH; (d) CH O. and why?
- Wed Nov 07, 2018 10:03 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration 3.27
- Replies: 1
- Views: 258
Electron Configuration 3.27
On the basis of the expected charges of the monatomic ions, what is the chemical formula of each of the following compounds: (a) thallium(III) chloride; (b) aluminum sulfide; (c) manganese(IV) oxide?
- Tue Oct 30, 2018 10:36 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chemical Bonds 3.21
- Replies: 1
- Views: 152
Chemical Bonds 3.21
What is the ground-state electron configuration and number of unpaired electrons expected for each of the following ions: (a) Ca2 ; (b) In ; (c) Te2 ; (d) Ag?
- Tue Oct 30, 2018 10:36 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chemical Bonds 3.13
- Replies: 1
- Views: 234
Chemical Bonds 3.13
For each of the following ground-state atoms, what is the type of orbital from which an electron will need to be removed to form the +1 ions: (a) Zn; (b) Cl; (c) Al; (d) Cu?
- Tue Oct 30, 2018 10:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electron Configuration
- Replies: 1
- Views: 133
Electron Configuration
What is the ground-state electron configuration expected for: (a) Cu ; (b) Bi3 ; (c) Ga3 ; (d) Tl3?
- Wed Oct 24, 2018 6:27 pm
- Forum: Trends in The Periodic Table
- Topic: Periodic Table 2.85
- Replies: 1
- Views: 152
Periodic Table 2.85
In the heavier transition-metal elements, especially the lanthanoids and actinoids, there are numerous exceptions to the regular order of orbital occupation predicted by the building- up principle. Why would more exceptions would be noted for these elements?
- Wed Oct 24, 2018 6:25 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy 2.81
- Replies: 1
- Views: 199
Ionization Energy 2.81
Ionization energies usually increase on going from left to right across the periodic table. The ionization energy for oxygen, however, is lower than that of either nitrogen or fluorine. How do you explain this anomaly?
- Wed Oct 24, 2018 6:21 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Properties 2.71
- Replies: 1
- Views: 163
Atomic Properties 2.71
What is a diagonal relationship? How does it arise? What are two examples that illustrate this concept?
- Wed Oct 17, 2018 2:52 pm
- Forum: Properties of Light
- Topic: Electromagnetic Radiation
- Replies: 3
- Views: 253
Electromagnetic Radiation
Why does the extent of change in the electrical field at a given point decrease when the frequency of the electromagnetic radiation decreases?
- Wed Oct 17, 2018 2:47 pm
- Forum: Properties of Light
- Topic: Intensity of Light
- Replies: 2
- Views: 241
Intensity of Light
What does it mean when light has high intensity? How is high intensity light different?
- Wed Oct 17, 2018 2:45 pm
- Forum: Properties of Light
- Topic: Intensity vs. Amplitude
- Replies: 5
- Views: 381
Intensity vs. Amplitude
Is the intensity of photons related to the amplitude of a wave?
- Fri Oct 12, 2018 3:05 pm
- Forum: Properties of Electrons
- Topic: Quantum Theory 1.27
- Replies: 1
- Views: 240
Quantum Theory 1.27
A lamp rated at 32 W emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time interval?
- Fri Oct 12, 2018 3:03 pm
- Forum: Properties of Electrons
- Topic: Quantum Theory 1.25
- Replies: 1
- Views: 250
Quantum Theory 1.25
Sodium vapor lamps, used for public lighting, emit yellow light of wavelength 589 nm. How much energy is emitted by an excited sodium atom when it generates a photon?
- Fri Oct 12, 2018 2:50 pm
- Forum: DeBroglie Equation
- Topic: De Brogile wavelengths
- Replies: 1
- Views: 101
De Brogile wavelengths
How can we classify if a particle has any measurable wavelike properties? Why aren't we able to measure wavelike properties of a moving particle if it is too small?
- Sat Oct 06, 2018 6:15 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants M9 [ENDORSED]
- Replies: 2
- Views: 372
Limiting Reactants M9 [ENDORSED]
Copper (II) nitrate reacts with sodium hydroxide to produce a precipitate of light blue copper (II) hydroxide. (a) How would know how to find the chemical equation for this reaction?
- Sat Oct 06, 2018 6:13 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants M11
- Replies: 2
- Views: 904
Limiting Reactants M11
A reaction vessel contains 5.77g of white phosphorus and 5.77g of oxygen. The first reaction to take place is the formation of phosphorus (III) oxide, P406:P4(s) + 302 (g) ---> P4O10 (s). (a) What is the limiting reactant for the formation of P4O10? (b) What mass of P4O10 is produced? (c) How many g...
- Sat Oct 06, 2018 5:06 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants M19
- Replies: 4
- Views: 460
Limiting Reactants M19
A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g mol 1. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. How would you find the empirical and molecular formulas of caffeine, and write the equation for its...