CHEMISTRY COMMUNITY

April P 1C

For acidic solutions, you balance O atoms by adding H2O and balance H atoms by adding H+. Since you added H2O atoms to the reactants side you had to add H+ to the other side to balance the H atoms you added

April P 1C

How come Q= 1/[K+]

April P 1C

I am also confused. Also, does anyone know if we will have to write the proposed structures for the exam?

April P 1C

The rate law of any reaction is always given by the slow step. Therefore, because the second step is fast, you can ignore the second step.The Rate law for the formation of NOBr will then be Rate=k[NO][Br2] since the slow step says NO +Br2 -> NOBr2

April P 1C

The solution from Chegg helped me FOR PART A) 15.67 The presence of a catalyst provides a reaction pathway in which the activation energy (Ea) of a certain reaction is reduced from 125kjmol^-1 to 75kjmol^-1 a) By what factor does the rate of the reaction increase at 298K, all other factors being equ...

April P 1C

When do I use kt=lnA./A
and when do I use kt=2.303logA./A

April P 1C

On chegg part of the solution is written :

[A] = [A]* - ([B]/2)
[A] = (0.153)- 2(0.034) = 0.085

Why is the first part written as ([B]/2) ?

April P 1C

The half-life of a substance is the time needed for its concentration to fall one-half its initial value. It doesn't depend on concentration.

April P 1C

Unique average rate depends on the coefficients used in the balanced equation.

For reaction aA =bB -> cC+ dD,
Unique average reaction rate= -(1/a) delta[A] / delta t = -(1/b) delta[B] / delta t = (1/c) delta[C] / delta t = (1/d) delta[D] / delta t

April P 1C

Here, this helped me out: "Zero-order kinetics is always an artifact of the conditions under which the reaction is carried out. For this reason, reactions that follow zero-order kinetics are often referred to as pseudo-zero-order reactions. Clearly, a zero-order process cannot continue after a ...

April P 1C

Write the half reactions and devise a galvanic cell
a) AgBr (s) -> Ag+ (aq) +Br- (aq), solubility equilibrium

Why is the half reaction for reduction : Ag+(aq) + e- -> Ag (s)
Why can't it be AgBr (s) -> Br- (aq) ?

April P 1C

d) Au^(+) (aq) -> Au(s) + Au^(3+) (aq) Why can't I use Au+ (aq) -> Au^(3+) (aq) for the oxidation half reaction? When I used that I was able to get the correct overall balanced redox reaction. And when I got the cell diagram, couldn't I have placed Pt(s) on the anode side? The solutions don't have t...

April P 1C

Someone correct me if I'm wrong but I think the reason why O2 and H+ are on the same side is because the reaction would not be oxidizing if it was either
H+ -> O2 or
O2 -> H+
The equation has to be H2O -> O2 + H+ because then the reaction will be oxidizing for H in H2O -> H+

April P 1C

14.11 Write the half reactions and the balanced equation for the cell reaction for each of the following galvanic cells: d) Pt(s) | O2 (g) | H+ (aq) || OH-(aq) | O2 (g) | Pt(s) I know that on the left of the || is anode and the right is cathode. Oxidation occurs at anode and reduction occurs at cath...

April P 1C

Br2(l)-> BrO3-(aq) + Br-(aq) I'm having a hard time finding numbers for H2O and OH- when balancing the Hydrogens. Does anyone have any tips/tricks?? I know that since it's basic, to balance the hydrogens I have to add H20 to the side that needs H, and then add OH- to the other side. So far I have ?O...

April P 1C

How do you determine if a reaction is acidic or basic? Can you tell just by looking at the reaction given?

April P 1C

Please write the full problem too

April P 1C

For part d, to determine the balanced equation, you multiply the oxidation half reaction by 3 and then add it with reduction half reaction. Oxidation: 3C2HxOH->3C2H4O + 6H +6e- Reduction: Cr2O7^(2-) +14H +6e- -> 2Cr^(3+) +7H2O The electrons cancel out. Balanced Redox Reaction: 3C2H5OH + Cr2O7^(2-) +...

April P 1C

Why do we use H+ to balance the hydrogens in a redox rxn instead of H2?

April P 1C

In class, Lavelle said that he won't ask us to derive anything for the exam, but it will still be helpful to know how.

April P 1C

Also from chegg, it states that entropy change depends on space for disorder, so since there is more space in the exterior there will be more disorder

April P 1C

9.105 states " The dissolution of carbon dioxide in red blood cells is catalyzed by the enzyme carbonic anhydrase: CO2(g) + H2O(l) -> H2CO3(aq) . Predict the sign of the entropy of reaction from a visual inspection of the equation and explain your reasoning." On Chegg, it says that one mol...

April P 1C

Hi, unfortunately I wasn't able to make Monday's lecture. Can someone tell me what topics were discussed on Monday so I can look up some videos to review it? Or if you could email me your notes that would be helpful too.
aprilfaeee@gmail.com

April P 1C

I got -2.7kj/mol also. I think the solutions just had an error.

April P 1C

For 11.77 Predict whether each of the following equilibria will shift toward products or reactants with a temperature increase. a) N2O4 (g) (equilibrium arrows) 2NO2(g) , deltaH =+57 kj How am I supposed to predict this? From my notes I know that there will be a shift towards reactants if delta G is...

April P 1C

Also, for homework/tests, if I forget to write naught in the equations/answers then will I miss points?

April P 1C

Can someone explain the difference between deltaG and deltaG* naught

April P 1C

11.15 (a) Calculate the reaction Gibbs free energy of I2(g) -> 2 I(g) at 1200. K (K=6.8) when the partial pressures of I2 and I are 0.13 bar and 0.98 bar, respectively.

I used deltaG* =-RTlnK
and then used
deltaG=deltaG*+RTlnQ

I'm not getting the correct answer though. How do I calculate Q?

April P 1C

"Oxygen disulfide is a colorless, very poisonous gas that reacts rapidly with water vapor to produce O2, HF, and heat: OF2(g) + H2O(g) -> O2(g) +2HF(g) deltaH=-318kJ" This is what I did to solve the problem: PV=nRT -> PdeltaV=deltanRT deltaU=q+w w=-PdeltaV=-deltanRT q=deltaH=-318J (given) ...

April P 1C

How did you get T=298?

April P 1C

For 8.31 "Calculate the heat released by 5.025 g of Kr(g) at 0.400atm as it cools from 97.6C to 25.0C at
(a) constant pressure and
(b) constant volume.
Assume that krypton behaves as an ideal gas. "

q=nCpdeltaT
Is there a table I need in the textbook that I should use to look up Cp?

April P 1C

If heat is transferring from a metal to water, is the metal itself the system? Or do both the metal and water form the system?

April P 1C

On Wednesday 01/17,

"In a constant P calorimeter at 25C mix 50.0ml each of 1.0 M HCl and 1.0M NaOH. After mixing T=31.9C

How much heat is released?"

Why did Professor Lavelle say we needed to know the density of water?

April P 1C

"Before the introduction of chlorofluorocarbons, sulfur dioxide (enthalpy of vaporization, 6.00 kcal/mol) was used in household refrigerators. What mass of SO2 must be evaporated to remove as much heat as evaporation of 1.00 kg of CCl2F2 (enthalpy of vaporization is 17.4 kj/mol)? The vaporizati...

April P 1C

Isolated systems have no contact with its surroundings. This means they cannot exchange matter or energy with the surroundings. From the textbook, "A system with adiabatic walls is not necessarily an isolated system: energy may be transferred to or from a system in an adiabatic container as wor...

April P 1C

"Indicate whether each of the following statements about an adiabatic process in a closed system is always true, always false or true in certain conditions (specify the conditions):" a) delta U = 0 (true only if no work) d) deltaU = q (true if w=0) I got a little bit confused since the tex...

April P 1C

Oh so I realized that it's q(water)= NEGATIVE q(copper)

April P 1C

" A piece of copper of mass 20.0 g at 100.0 degrees C is placed in a vessel of negligible heat capacity but containing 50.7 g of water at 22.0 degrees C. Calculate the final temperature of the water. Assume that no energy is lost to the surroundings. " I solved this by using q=mCsdeltaT an...

CHEMISTRY COMMUNITY

Search found 38 matches

Re: Balancing for Acidic Conditions

Re: 14.101

Re: 15.85

Re: 15.51? Molecularity?

Re: 15.67?

First Order Integrated Rate Law

Re: 15.23?

Re: Half-life of first order reactions [ENDORSED]

Re: What role do coefficients play?

Re: Real Life Example

14.15

14.13

Re: 14.11

14.11

14.5

Acidic or basic?

Re: Exercise 14.17

Re: 14.1

H+ vs H2

Re: Constants and formulas

Re: 9.101 (b) [ENDORSED]

9.105

Monday 02/05 Lecture

Re: 11.17

11.77

Re: Difference between deltaG and deltaG*

Difference between deltaG and deltaG*

11.15 Gibbs Free Energy and Q

8.49

Re: Homework 8.49

Hmwk Q 8.31

Re: Assigning system/surroundings

Wed 01/17 Lecture

What mass of SO2 must be evaporated?

Re: Isolated vs. Adiabatic system

Q. 8.15

Re: Homework Question 8.21

Homework Question 8.21