Search found 18 matches

by JohnArthurReyes_1B
Thu Mar 10, 2016 9:07 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 2015 5A Nernst Equation understanding
Replies: 1
Views: 329

2015 5A Nernst Equation understanding

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in This problem why is E cell=0.00V?
Additionally, what part of the question lets us know that n=1? It doesn't explicitly say 1 mol of an element is being used. For future problems, if n isn't stated directly, what gives it away.
by JohnArthurReyes_1B
Wed Mar 09, 2016 3:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Winter 2014 #3 highest possible charged chemicals?
Replies: 1
Views: 315

Winter 2014 #3 highest possible charged chemicals?

IN this problem we are told to circle the chemicals with the highest possible charges and solve for a galvanic cell. How do you which elements have the highest charges? The elements given are Zn(s), Cu(s), Fe(s), Zn(NO3)2(aq), Fe(NO3)2, Pt(s), Cu(NO3)2(aq), and Fe(NO3)3 (aq) -solution says all of th...
by JohnArthurReyes_1B
Tue Mar 08, 2016 10:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Final exam 2015 #1c Enthalpy with heat and mass
Replies: 3
Views: 478

Final exam 2015 #1c Enthalpy with heat and mass

In this problem we are told that Frodo's ring takes 390 KJ of heat to fully melt the ring. We have to find the enthalpy of fusion of the ring. I don't understand conceptually why we divide heat by mass to get enthalpy.
by JohnArthurReyes_1B
Tue Mar 08, 2016 7:00 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Chemistry Practice final 1B 2013 Entropy
Replies: 1
Views: 458

Chemistry Practice final 1B 2013 Entropy

In this problem we are given a balloon filled with .13 moles of helium into the air. as the balloon rises, the temperature of the helium decreases and the balloon expands due to the decrease in external temperature and pressure at higher altitudes. If the helium in the balloon started at 3.0 L and 2...
by JohnArthurReyes_1B
Mon Feb 22, 2016 5:30 pm
Forum: *Cycloalkanes
Topic: Quiz 3 prep #1 Cyclo problem
Replies: 2
Views: 472

Quiz 3 prep #1 Cyclo problem

In this problem we are given a compound with a solution of 1-chloro-3-methylcyclopentane. Why wouldn't the answer be 3-chloro-1-methylcyclopentane? Is there a special rule for cycloalkane structures when designating numbers?
by JohnArthurReyes_1B
Sat Feb 13, 2016 11:42 am
Forum: General Rate Laws
Topic: Quiz prep winter 2013 #1
Replies: 1
Views: 362

Quiz prep winter 2013 #1

Given: 2MBr2 + O2 -> 2MO + 2Br2/ Mbrs goes from 10 mmol/l to 6.0 mmol/l in 200 seconds. What is reacion rate over time period? I understand reaction rate is equal to change of concentration divided by time but the solution multiplies change in concentration over time by -1/2 why is that?
by JohnArthurReyes_1B
Sat Feb 06, 2016 5:49 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal concept
Replies: 2
Views: 522

Isothermal concept

Why can isothermal conditions be reversible and irreversible? What condition distinguishes the two other than the different formulas for work.
by JohnArthurReyes_1B
Wed Dec 02, 2015 8:39 pm
Forum: Polyprotic Acids & Bases
Topic: Concept Question Q7B 2009 Final
Replies: 2
Views: 721

Concept Question Q7B 2009 Final

How is autoprotolysis related to the concept that [H3O+]+[OH-]=14? The problem asks for the concentration of acetic acid when the autoprotolysis of water needs to be taken to account. All we're given is KA=10^-7 M
by JohnArthurReyes_1B
Mon Nov 30, 2015 6:18 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Value of Kw question
Replies: 6
Views: 11489

Value of Kw question

The value of Kw for water at body temperature (37°C) is 2.1 X 10^-14. (a)What is the molarity of H3O+ ions and the pH of neutral water at 37°C? (b) What is the molarity of OH- in neutral water at 37"C? For part a, I understand that Kw=[H3O] [OH-] and were given Kw so 2.1 x 10^-14=[H30] [OH-]. I...
by JohnArthurReyes_1B
Mon Nov 30, 2015 6:08 pm
Forum: Lewis Acids & Bases
Topic: Lewis acid/base conceptual question?
Replies: 1
Views: 613

Lewis acid/base conceptual question?

Why is Ag+ considered a Lewis acid if it electron configuration has 1 lone electron and 3 lone pairs? Wouldn't it's electron be donated to a compound since the lone electron makes it highly reactive? Also, just to confirm, H- and F- are Lewis bases because F- is a full octet and can donate and H- is...
by JohnArthurReyes_1B
Thu Nov 05, 2015 9:45 am
Forum: Naming
Topic: 17.31 (A) giving formula based on name
Replies: 1
Views: 966

17.31 (A) giving formula based on name

Question 17.31 asks to give the formula given the coordination name potassium hexacyanidochromate(III) I understand that hexa means there are 6 cyanide atoms,the III means that chromium has a charge of 3+, and the chromate signifies that the net charge of the compound is negative. This understanding...
by JohnArthurReyes_1B
Fri Oct 30, 2015 9:25 am
Forum: Lewis Structures
Topic: Fall 2011 Midterm Q8A Structure of (CH3)^2 SO
Replies: 1
Views: 440

Fall 2011 Midterm Q8A Structure of (CH3)^2 SO

For the given structure how do you determine the lewis structure as well as how many valence electrons the compound has. The answer it shows has an H3C,O, and CH3 connected to a central S. The diagram shows only 14 valence electrons. A single bond connecting Ch3 and H3C to S, a double bond connectin...
by JohnArthurReyes_1B
Fri Oct 30, 2015 9:16 am
Forum: Ionic & Covalent Bonds
Topic: Fall Midterm 2011 Q6B Which is more ionic?
Replies: 1
Views: 368

Fall Midterm 2011 Q6B Which is more ionic?

In question 6b of the 2011 midterm the question gives 4 sets of compounds and asks which is more ionic. I understand that the farther apart two elements composing a compound equates to a more ionic identity while the closer two elements are the more covalent they are. Part C of this question gives L...
by JohnArthurReyes_1B
Fri Oct 30, 2015 9:11 am
Forum: Properties of Light
Topic: Midterm 2010 #5 Strength of visible light
Replies: 1
Views: 465

Midterm 2010 #5 Strength of visible light

In 2010 the question asks if the energy to break a C-C bond is 348 kJ/mol, will visible light be able to break it. It then asks what color if yes or what type of radiation if no. The given value ends up converting to 344 nm. Why can visible light break this bond since the range of visible light is 4...
by JohnArthurReyes_1B
Sun Oct 25, 2015 7:37 pm
Forum: Hybridization
Topic: Fall 2012 #3
Replies: 1
Views: 308

Fall 2012 #3

When depicting the electron configuration is it ok to write (Pi2p)^4 instead of (Pi2px)^2, (Pi2py)^2. Also, I understand that if the atomic number of the elements in your compound are greater than 8 sigma comes first and if its lower pi comes first, but what comes first when your given a compound th...
by JohnArthurReyes_1B
Sat Oct 10, 2015 10:40 pm
Forum: Empirical & Molecular Formulas
Topic: Types of chemical reactions
Replies: 1
Views: 437

Types of chemical reactions

This problem asks for the amount of pure Si produced when 63.7 g of Mg and 36.7 g of SiCl4 react. I understand that this is a substitution reaction where chemical equation turns out to be 2Mg + SiCl4 -> Si + 2MgCl2 based on the charge of Mg and Cl. What other type of reactions should I learn that co...
by JohnArthurReyes_1B
Fri Oct 02, 2015 2:20 pm
Forum: DeBroglie Equation
Topic: 1.39
Replies: 1
Views: 414

1.39

This problem required the mass of a neutron(1.673 * 10^-27) . This value wasn't explicitly given in the question. For future tests/quizzes would it be wise to memorize the mass of neutrons, electrons, and protons or are they given to us on a formula sheet?

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