Search found 26 matches
- Mon Mar 13, 2017 6:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q=mc∆t vs q=c∆t? (chapter 8)
- Replies: 2
- Views: 35535
Re: q=mc∆t vs q=c∆t? (chapter 8)
The C given in the problem is in units of kJ/C. You want your q to be in units of Joules or kJ. If you used the q=mC(delta T) with your given C, your q would be in units of (grams)(kJ). In the problem, you were given the heat capacity, not the specific heat capacity. Therefore, you don't need mass t...
- Tue Mar 07, 2017 8:18 pm
- Forum: *Alkanes
- Topic: Electrophilic Addition versus Substitution
- Replies: 1
- Views: 487
Re: Electrophilic Addition versus Substitution
Addition: you start off with two molecules for reactants, you end up with one molecule in products.
Substitution: you start off with two molecules for reactants, you end up with two molecules in products.
Substitution: you start off with two molecules for reactants, you end up with two molecules in products.
- Tue Mar 07, 2017 8:09 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Relationship between activation energy and temperature
- Replies: 1
- Views: 2448
Re: Relationship between activation energy and temperature
Ea= deltaH + RT is just an approximation. To find the actual Ea, (deltaG of activation)= (deltaH of activation) -T(deltaS of activation). But, in practice the deltaG equation is difficult to use because it's difficult to know what the activated complex is. Therefore, in reality, one would use Ea= de...
- Tue Feb 28, 2017 4:43 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
- Mon Feb 20, 2017 11:54 pm
- Forum: General Rate Laws
- Topic: Quiz Prep Question
- Replies: 1
- Views: 491
Re: Quiz Prep Question
second order process means that rate=k[NO2]^2 must find [NO2]: 0.42 g NO2*(mol NO2/46 g)/0.15 L = 0.06087 mol NO2/L rate= k[NO2]^2 =(0.54 L/mol/s)* (0.06087 mol NO2/L)^2 = 0.0020 mol/l/s = initial rate For second part of the question, repeat above process with new initial amount of NO2 and then comp...
- Tue Feb 14, 2017 11:54 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: book question 9.13
- Replies: 1
- Views: 527
Re: book question 9.13
"In the process, the temperature of the gas increased to 28.1 degrees C." During the process, volume decreased from 3.00 L to 0.500 L. Volume did not remain constant, so you cannot use Cv. The solution works because entropy is a state function. You can calculate the change in entropy when ...
- Tue Feb 14, 2017 11:45 am
- Forum: Calculating Work of Expansion
- Topic: 9.47
- Replies: 2
- Views: 800
Re: 9.47
I don't think delta S is dependent on whether or not the process is reversible or irreversible. In both cases volume increased for the gas, which means disorder of the gas molecules increases (delta S increases).
- Mon Feb 06, 2017 10:13 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
- Thu Feb 02, 2017 8:42 pm
- Forum: Calculating Work of Expansion
- Topic: Amount of work done
- Replies: 2
- Views: 700
Re: Amount of work done
It's a maximum theoretical yield. In real life, things tend to go toward entropy. When doing experiments, there's always a small percentage of error.
- Mon Jan 23, 2017 10:34 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Hmwk Problem 8.91
- Replies: 1
- Views: 414
Re: Hmwk Problem 8.91
Well, the water took 0.5 hours and 3135 J. The problem is saying that the ice took 10 hours to melt. There are 20 half hours in the period of 10 hours. In 1 hour, there are 2 half hours. (10 hours)*(2 half hours/1 hour)= (10 hours/ 0.5 hours) = 20 half hours. Water took 3135 J in half an hour. Ice w...
- Mon Jan 16, 2017 11:43 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard State [ENDORSED]
- Replies: 1
- Views: 605
Re: Standard State [ENDORSED]
Standard state of a liquid is a liquid. Standard state of a solid is a solid. Standard state of an element is whatever state it is found in at 1 atm and at 25 degrees C. For example, the standard state of bromine is liquid because at 1 atm and 25 degrees C, bromine is found as a liquid.
- Sat Jan 14, 2017 2:07 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Titrations & Enthalpy Change
- Replies: 1
- Views: 592
Re: Titrations & Enthalpy Change
When doing titrations, H+ and OH- ions would combine to form H2O. The bond formation of H2O gives off heat, heat under a constant pressure (enthalpy).
- Tue Nov 29, 2016 10:09 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Calculating pH - Group 1 and Group 7
- Replies: 1
- Views: 564
Re: Calculating pH - Group 1 and Group 7
Na+ and Cl- are not strong enough to change H2O on a molecular level. Meaning that OH- or H3O+ are not produced when NaCl is added. Therefore the pH does not change.
- Mon Nov 21, 2016 1:42 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
- Mon Nov 21, 2016 1:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.79
- Replies: 2
- Views: 565
Re: 11.79
I don't think so. To solve that problem, you would need a graphing calculator and we are only allowed scientific calculators.
- Mon Nov 14, 2016 1:33 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
- Wed Nov 09, 2016 6:55 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
- Mon Oct 31, 2016 2:34 pm
- Forum: DeBroglie Equation
- Topic: 2006 MT #3
- Replies: 1
- Views: 598
Re: 2006 MT #3
h/p and hp^-1 are the same thing. p^-1 puts p in the denominator.
- Mon Oct 31, 2016 2:32 pm
- Forum: Resonance Structures
- Topic: Stable Lewis Structures
- Replies: 3
- Views: 915
Re: Stable Lewis Structures
It would be best to draw the most stable structure (based on formal charge).
- Mon Oct 31, 2016 2:29 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
Re: Post All Chemistry Jokes Here
If you're not part of the solution, then you're part of the precipitate.
- Mon Oct 31, 2016 2:19 pm
- Forum: Hybridization
- Topic: Hybridization for the midterm
- Replies: 2
- Views: 684
Re: Hybridization for the midterm
based on number of regions of electron density
- Mon Oct 24, 2016 2:31 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3862796
Re: Post All Chemistry Jokes Here
Are you made of Fluorine, Iodine, and Neon? 'Cause you are F-I-Ne
- Wed Oct 19, 2016 2:10 pm
- Forum: Ionic & Covalent Bonds
- Topic: Difference in Electronegativity [ENDORSED]
- Replies: 3
- Views: 1067
Re: Difference in Electronegativity [ENDORSED]
Before between 2 and 1.5, one has to look specifically at the heteronuclear atoms. Case by case basis.
- Mon Oct 10, 2016 5:06 pm
- Forum: Properties of Light
- Topic: Rydberg Equation
- Replies: 5
- Views: 1318
Re: Rydberg Equation
You can use either one. I personally use the E=-hR/n^2 because I understand what I am looking for. That equation would tell me the energy of the specific energy level and I can follow that. I don't like using the Rydberg equation because I don't understand how I can get from energy levels to wavelen...
- Wed Oct 05, 2016 4:43 pm
- Forum: Einstein Equation
- Topic: 1.65 : Will visible light be able to break C-C bond? [ENDORSED]
- Replies: 1
- Views: 6728
Re: 1.65 : Will visible light be able to break C-C bond? [ENDORSED]
Converting kJ/mol to joules: 348 kJ/mol * (1000 J/ 1 kJ) * (1 mol of C-C bonds/6.022x10^23 C-C bonds) = 5.78x10^-19 J Plug 5.78x10^-19 J for E in the equation E=hc/(lamda). Solve for lamda. You would get 3.44x10^-7 m or 344 nm. Visible light wavelength is within the range of 700nm and 400 nm. Theref...
- Wed Sep 28, 2016 12:23 am
- Forum: Student Social/Study Group
- Topic: Chemistry Jokes
- Replies: 31
- Views: 9018