## Search found 21 matches

Mon Mar 07, 2016 5:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Winter 2012 Final Question 3
Replies: 1
Views: 372

### Re: Winter 2012 Final Question 3

a) You will be given a list of half-reactions. Look at pg. 123 of the course reader for all the half-reactions. There are two ways of solving for E. You can do cathode minus anode or flip the anode's sign and add it the cathode. You want E to be positive in order for the reaction to be spontaneous. ...
Mon Feb 29, 2016 7:20 pm
Forum: *Cycloalkenes
Topic: HW Question: 1.21
Replies: 2
Views: 385

### Re: HW Question: 1.21

I believe that in lecture we learned that there is not such thing as a sum rule. Rather, we just want the lowest numbering possible. Each tip of the pentagon represents a C. Double bonds get priority in naming versus the substituent so you want to start with the double bond. It does not matter which...
Tue Feb 23, 2016 11:42 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Section 4.3 HW number 4.30
Replies: 1
Views: 276

### Re: Section 4.3 HW number 4.30

For #30, you do not need to use an equation to solve it. On pg. 154, it states that "reactions with activation energies below 80 kj/mol can occur at room temperature, while those with larger activation energies require energy input to occur". The activation energy for #30 is 125 kj/mol, so...
Thu Feb 18, 2016 9:40 am
Forum: General Rate Laws
Topic: Deriving Rate Laws
Replies: 1
Views: 341

### Re: Deriving Rate Laws

The reaction that we derived the integrated rate law from during lecture was A \rightarrow P The reactant has a coefficient of 1. 1/a=1 in that case. Because it was 1, a constant; in a sense, it went away. If the coefficient for the reactant had not been 1, then it would 1/the coefficient of the rea...
Tue Feb 09, 2016 7:34 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Midterm Winter 2014 Q. 7 and 8
Replies: 2
Views: 525

### Re: Midterm Winter 2014 Q. 7 and 8

If the question says that it is a galvanic cell, you would look at cell potential because E has to be positive for a galvanic cell. So you would make the cathode the more positive one and the anode the negative one. If it does not say that it is a galvanic cell, you look at the balanced equation. In...
Wed Feb 03, 2016 9:15 pm
Forum: Balancing Redox Reactions
Topic: Cell Potential and Balancing Half Reactions
Replies: 1
Views: 223

### Re: Cell Potential and Balancing Half Reactions

This is because there are two ways of solving for cell potential. 1. The formula for cell potential is cathode minus anode. The anode value is the same as the cathode. For this problem that would be 0.80-(-0.23 V)= +1.03 V. 2. Another way of getting cell potential would be reversing the sign of the ...
Mon Jan 25, 2016 10:22 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Question #3 winter 2014 quiz practice
Replies: 3
Views: 574

### Re: Question #3 winter 2014 quiz practice

The first step would be to balance the reaction. After balancing the equation you would draw the Lewis structures of each reactant and product. Comparing these Lewis Structures, you can see which bonds have been broken and which bonds have been formed. Next, sum up all the bonds. Breaking a bond is ...
Tue Jan 19, 2016 9:21 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: HW 8.25
Replies: 4
Views: 702

### Re: HW 8.25

It actually does not matter whether Celsius or K is used because a change of 1 degree Celsius is the same as a change of 1 K. This is because K= C + 273. The numbers differ by 273, but if there is any change in C, the same change will occur in K.
Tue Jan 19, 2016 9:14 pm
Forum: Phase Changes & Related Calculations
Topic: Determining whether a reaction is exothermic or endothermic
Replies: 2
Views: 468

### Determining whether a reaction is exothermic or endothermic

8.113 gives the reaction C(s) + H2O (g) \rightarrow CO (g) + H2 (g) It then asks whether the reaction is exothermic or endothermic. Besides calculating the enthalpy change directly, how would you figure out whether the above reaction is exothermic or endothermic? Also, what are some general key thin...
Thu Jan 14, 2016 6:53 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimetry Calibrations
Replies: 2
Views: 632

### Re: Calorimetry Calibrations

This is because you are using heat capacity, which is the amount of heat needed to raise the temperature of an object (no mass specified) by one degree. Another way to find qcal would be qcal=mass x Cs x delta T. Mass is part of this equation because you are using specific heat which is the amount o...
Sat Jan 09, 2016 7:38 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: HW 8.25
Replies: 4
Views: 702

### Re: HW 8.25

Heat capacity is linked to internal energy because heat capacity is equal to heat supplied/temperature change, which in equation form is C= q/delta T Change in internal energy (delta U) is equal to q (heat) + w (work) Because the problem specifies that it is a constant-volume calorimeter, w= 0 in th...
Mon Nov 30, 2015 5:13 pm
Forum: Calculating the pH of Salt Solutions
Topic: Relation between pH and pKa and pKb
Replies: 1
Views: 6098

### Re: Relation between pH and pKa and pKb

The larger the Ka the stronger the acid. Because pKa= - log Ka, the larger the Ka, the lower the pKa, the stronger the acid. ex: If Ka = 10^-7, then pKa= 7 Ka= 10^-4, then pKa=4 Acids have a low pH. A low pKa is associated with a low pH. A low pKb means a strong base. Thus, a high pKb means it would...
Tue Nov 24, 2015 2:10 pm
Forum: Calculating the pH of Salt Solutions
Topic: HW 12.65e
Replies: 1
Views: 336

### HW 12.65e

The solution manual lists the equilibrium equation for AlCl3 (a conjugate acid) to be
Al(H2O)6 (aq) + H2O (l) H3O+ (aq) + Al(H2O)5OH (aq)

Can someone please explain why the equilibrium equation for AlCl3 includes water bounded to Al? Because for 12.65c, it is just F-?
Sun Nov 15, 2015 9:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination compounds with a molecule outside the brackets
Replies: 2
Views: 509

### Re: Coordination compounds with a molecule outside the brack

Cl2 acts as a counter ion for the complex. In other words, Cl2 neutralizes the coordination compound. Because you know that Cl has a 1- charge and there are 2 of them, you know that the coordination compound has a 2+ charge. From there you can determine the oxidation state of the metal because NH3 i...
Mon Nov 09, 2015 10:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding the value of equilibrium constant
Replies: 1
Views: 292

### Re: Finding the value of equilibrium constant

The key to doing 11.37 is comparing the equations to the original equation given. For example, to find K for 11.37a, K= [N2][H2]^3/ [NH3]^2 based on the problem given. Comparing this to the original K of [NH3]^2/[N2][H2]^3, you will notice that the two are inverses of each other. Therefore K is equa...
Fri Nov 06, 2015 2:32 pm
Forum: Naming
Topic: Naming Metals
Replies: 1
Views: 287

### Re: Naming Metals

This is because the -ate is added to the end of the metal when there is a net negative charge. K is a counter ion for the complex so it neutralizes the whole coordination compound. K has a 1+ charge so you with 3 of them, it has a 3+ charge. Because it is a counter ion, you know the coordination com...
Tue Oct 27, 2015 9:18 pm
Forum: Lewis Structures
Replies: 1
Views: 286

This is because C is less electronegative than O. Thus, O would attract the electrons more and fulfill its octet first.
Mon Oct 19, 2015 4:17 pm
Forum: Lewis Structures
Topic: Lewis structure of hydrogen sulfite
Replies: 1
Views: 534

### Lewis structure of hydrogen sulfite

This problem asks for the lewis structure of Hydrogen Sulfite. Hydrogen Sulfite is HSO3- I used S as my central atom because it has the lowest ionization energy and connected each O and H with a single bond to S. (4 elements attached to S) The solution manual attaches the H with a single bond to O i...
Mon Oct 12, 2015 10:25 pm
Forum: Trends in The Periodic Table
Topic: Electron Configuration problem 2.19
Replies: 2
Views: 2139

### Re: Electron Configuration problem 2.19

This is because l is dependent on n.

l= 0 n-1

n=7 which means that l can be 0,1,2,3,4,5,6

In this problem, n is 7, so the max value of l is 6.

There are 7 possible l values with 6 being the max.
Tue Oct 06, 2015 1:18 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question about Textbook Problem Chapter 1 (1.45)
Replies: 1
Views: 423

### Re: Question about Textbook Problem Chapter 1 (1.45)

You are correct; the uncertainty in velocity is 10. With a velocity of 5.00 +/- 5.0 m/s that would mean that the velocity lies in between 0 m/s and 10.0 m/s. The difference between these values is 10.0, which means the uncertainty in velocity is 10. According to Dr. Lavelle, the Solutions Manual con...
Mon Sep 28, 2015 9:43 pm
Forum: Properties of Light
Topic: Rydberg Formula
Replies: 7
Views: 2195

### Rydberg Formula

For Hw 1.13 (6th edition)/Hw 1.7 (5th edition), it the Rydberg formula is to be used for the transition from n= 4 to n =2. v (frequency)= R(\frac{1}{(n1)^2)}-\frac{1}{(n2)^2}) I used 4 as n1 and 2 as n2 because it was listed in that order. I checked the Solutions ...