Since you have the half life and initial concentration, you can solve for k using the equation for second order half-life
t(1/2) = 1/(k[A]naught)
After solving for k, you can use the second order equation
1/[A] = kt + 1/[A]naught
Plug in 2.00M for [A], 5.00M for [A]naught, and k
then solve for t
Search found 53 matches
- Wed Mar 14, 2018 12:59 am
- Forum: Second Order Reactions
- Topic: Test 3 #8
- Replies: 2
- Views: 557
- Wed Mar 14, 2018 12:53 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Test 2 Question 8b
- Replies: 9
- Views: 1493
Test 2 Question 8b
Wednesday in Dane's section Consider the following unbalanced half reactions Hg2Cl2(s) + 2e- -> 2Hg(l) + 2Cl-(aq) Enaught = +0.27V 2H+(aq) + 2e- -> H2(g) Enaught = 0.00V b) If PH2 = 2.0 bar, [H+] = 3.16x10^4 M and [Cl] = 0.75M, what is Q? For this problem, how to you deal with partial pressure and M...
- Wed Mar 14, 2018 12:43 am
- Forum: Balancing Redox Reactions
- Topic: Test 2 Question 8
- Replies: 2
- Views: 414
Re: Test 2 Question 8
I think for #8 they already gave you the balanced equation. If they didn't then you have to balance it using the steps for balancing redox equations. To find the number of electrons exchanged, you can look at the charges on both side of the equation. If you see any discrepancies between the charges ...
- Mon Mar 05, 2018 6:37 pm
- Forum: General Rate Laws
- Topic: unique reaction rate sign
- Replies: 2
- Views: 351
Re: unique reaction rate sign
I think they are always positive. I am pretty sure Dr. Lavelle said something about there is no such thing as a negative rate, at least for what we are doing
- Mon Mar 05, 2018 6:33 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3940997
Re: Post All Chemistry Jokes Here
Your dad's been under a lot of pressure lately
- Mon Mar 05, 2018 6:23 pm
- Forum: Zero Order Reactions
- Topic: Units of k
- Replies: 12
- Views: 2136
Re: Units of k
The units for zero order is mol/(L*s)
- Tue Feb 27, 2018 8:53 pm
- Forum: Experimental Details
- Topic: Homework Problem 15.3 Part C
- Replies: 5
- Views: 1142
Re: Homework Problem 15.3 Part C
Unique rate is calculated by dividing the rate of a species by its stoichiometric coefficient
- Tue Feb 27, 2018 8:47 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalytic Reactions
- Replies: 2
- Views: 358
Re: Catalytic Reactions
A catalyst is something that increases the rate of a reaction. I think photosynthesis is an example
- Tue Feb 27, 2018 8:43 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram order
- Replies: 4
- Views: 492
Re: Cell diagram order
In the textbook, it ways to write the oxidized form, reduced form; however in the solutions manual, sometimes they have the reduced form before the oxidized form, so I am not sure
- Tue Feb 20, 2018 4:37 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Homework 14.23c
- Replies: 2
- Views: 384
Re: Homework 14.23c
I guess I am trying to ask how do you know what order you put everything in in cell diagrams.
I thought that ions in solution are written in the order oxidized state, reduced state, so I was wondering why Pu3+(aq), Pu4+(aq) written with the reduced state first
I thought that ions in solution are written in the order oxidized state, reduced state, so I was wondering why Pu3+(aq), Pu4+(aq) written with the reduced state first
- Tue Feb 20, 2018 12:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Homework 14.17
- Replies: 1
- Views: 281
Homework 14.17
14.17 (a) Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride. (b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagram). anode: Fe 2+(aq) -> Fe 3+(aq) + e-...
- Tue Feb 20, 2018 12:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Pt in Cell diagrams
- Replies: 4
- Views: 690
Re: Pt in Cell diagrams
Pt is necessary when both the oxidized and reduced species are in the same solution
- Tue Feb 20, 2018 12:07 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Homework 14.23c
- Replies: 2
- Views: 384
Homework 14.23c
14.23 For each reaction that is spontaneous under standard conditions, write a cell diagram, determine the standard cell potential, and calculate delta G naught for the reaction: c) Cr2O7^2- (aq) + 14 H+ (aq) + 6 Pu3+ (aq) S -> 6 Pu4+ (aq) + 2 Cr3+ (aq) + 7 H2O(l) The cell diagram is Pt(s)IPu3+(aq),...
- Tue Feb 13, 2018 3:37 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Is it possible to force a reaction that will decrease the entropy of the universe?
- Replies: 1
- Views: 297
Re: Is it possible to force a reaction that will decrease the entropy of the universe?
The textbook says that "The natural progression of a system and its surroundings (which together make up “the universe”) is from order to disorder, from organized to random, from lower to higher entropy." Thus, I think that decreasing the entropy of the universe defies the second law of th...
- Tue Feb 13, 2018 2:36 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: constant pressure
- Replies: 2
- Views: 491
Re: constant pressure
If you are given enthalpy (H), then you can assume constant pressure, since q=deltaH under constant pressure
- Tue Feb 13, 2018 2:35 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Isothermal Systems and deltaU
- Replies: 2
- Views: 316
Re: Isothermal Systems and deltaU
Yes I think so
The textbook says "deltaU=0 for the isothermal expansion (or compression) of an ideal gas"
The textbook says "deltaU=0 for the isothermal expansion (or compression) of an ideal gas"
- Tue Feb 06, 2018 4:31 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.1
- Replies: 4
- Views: 651
Re: 9.1
I think it is talking about the surroundings
- Tue Feb 06, 2018 4:25 pm
- Forum: Balancing Redox Reactions
- Topic: Ozone oxidation number
- Replies: 2
- Views: 300
Re: Ozone oxidation number
I think it's 0
- Tue Feb 06, 2018 4:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Bruin Cast
- Replies: 5
- Views: 882
Re: Bruin Cast
I do not think it is
- Mon Jan 29, 2018 3:31 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: A spontaneous reaction
- Replies: 7
- Views: 997
Re: A spontaneous reaction
A spontaneous reaction is a reaction that is favorable (with a negative deltaG)
- Mon Jan 29, 2018 3:08 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Homework 9.5 [ENDORSED]
- Replies: 11
- Views: 1281
Re: Homework 9.5 [ENDORSED]
We use S=-q/T for the entropy at 800 K because heat released, and we use S=q/T for the entropy at 200 K because heat is absorbed by the reservoir
- Mon Jan 29, 2018 3:05 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Irreversible vs. Reversible Pathways
- Replies: 3
- Views: 453
Re: Irreversible vs. Reversible Pathways
Also, more work is done in reversible pathways than in irreversible pathways.
- Tue Jan 23, 2018 8:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: How to differentiate when to use certain formulas
- Replies: 3
- Views: 542
Re: How to differentiate when to use certain formulas
I think some of the main equations we need to know are
q=nC(deltaT)
w=-P(deltaV)
(deltaU)=q+w
q=nC(deltaT)
w=-P(deltaV)
(deltaU)=q+w
- Tue Jan 23, 2018 8:13 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units
- Replies: 2
- Views: 294
Re: Units
I think my ta said they would not take off points for either, but we should use kj/mol
- Tue Jan 23, 2018 8:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: When can we pick up our finals from Chem 14A?
- Replies: 3
- Views: 802
Re: When can we pick up our finals from Chem 14A?
In the email that Dr. Lavelle sent us, he said we can pick them up at 4006 Young Hall, Week 3 Winter quarter. But I do not know what time specifically
- Fri Jan 19, 2018 10:33 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: C(v) and C(p)
- Replies: 3
- Views: 276
Re: C(v) and C(p)
Gasses have Cp and Cv (specific heats at constant pressure and volume), but I think solids and liquids only have one value for specific heat
- Fri Jan 19, 2018 10:24 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capcity for Water
- Replies: 8
- Views: 720
Re: Heat Capcity for Water
Specific heat capacity for water(solid) is 2.03 J/g°C, water(liquid) is 4.184 J/g°C, and water(vapor) is 2.01 J/g°C
- Fri Jan 19, 2018 10:10 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Internal Energy/Open System
- Replies: 4
- Views: 596
Re: Internal Energy/Open System
You can increase the temperature of an open system and it will increase its internal energy, but I am not sure how effective it is to, say, heat up an open beaker where the heat can just leave
- Wed Jan 10, 2018 3:57 pm
- Forum: Phase Changes & Related Calculations
- Topic: Exothermic Rxn
- Replies: 6
- Views: 719
Re: Exothermic Rxn
Not all exothermic reactions are spontaneous, meaning that the reaction will occur without outside influence. Just because a reaction is exothermic doesn't mean that its reactants cannot be found naturally.
- Wed Jan 10, 2018 3:50 pm
- Forum: Phase Changes & Related Calculations
- Topic: qp=deltaH
- Replies: 8
- Views: 1021
Re: qp=deltaH
DeltaH is what people usually use, so I don't think we will use qp
- Wed Jan 10, 2018 3:43 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endo and Exothermic Ways to Remember
- Replies: 28
- Views: 11739
Re: Endo and Exothermic Ways to Remember
Also in chemistry, exothermic and endothermic refers to the system. Exothermic releases heat (so the surroundings feel warm) and endothermic requires heat (so the surroundings feel cool)
- Mon Dec 04, 2017 7:19 pm
- Forum: Lewis Acids & Bases
- Topic: Writing equations with acids and bases
- Replies: 5
- Views: 594
Re: Writing equations with acids and bases
I think we need to know what the strong acids/bases are
- Mon Dec 04, 2017 6:58 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: EDTA
- Replies: 2
- Views: 534
Re: EDTA
It can bind twice at the N and 4 times at the O
Re: Suffixes
The textbook says that "If the complex has an overall negative charge (an anionic complex), the suffix -ate is added to the stem of the metal’s name," so it does not matter if the ligand has a negative charge or not. Because 17.29d has an overall positive charge, no suffix is added to the ...
- Thu Nov 30, 2017 11:14 am
- Forum: Naming
- Topic: Trans & Cis Naming
- Replies: 3
- Views: 366
Re: Trans & Cis Naming
I think so? Otherwise you wouldn't know the placement of the molecules?
- Tue Nov 21, 2017 8:39 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Determining the direction of reaction
- Replies: 1
- Views: 245
Re: Determining the direction of reaction
To determine the direction of the reaction when given the INITIAL concentrations and a K value, find Q, which equals [C][D]/[A][B] (it looks like k) for A+B->/<-C+D.
And if Q<K, reaction will go forward; Q>K reaction will reverse; Q=K at equilibrium
And if Q<K, reaction will go forward; Q>K reaction will reverse; Q=K at equilibrium
- Tue Nov 21, 2017 8:35 am
- Forum: Conjugate Acids & Bases
- Topic: Strong vs Weak Acids/bases
- Replies: 4
- Views: 935
Re: Strong vs Weak Acids/bases
I think the strength of acids is based on percent of dissociation; strong acids are assumed to be 100% dissociated in aqueous environments. Strong bases are usually salts with -OH (there are exceptions)
- Wed Nov 15, 2017 6:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determing Molecular Shape
- Replies: 2
- Views: 252
Re: Determing Molecular Shape
I think the one electron should be put on the less electronegative atom (central atom) because the more electronegative one will be more attractive to electrons and have its octet filled
- Wed Nov 15, 2017 6:36 pm
- Forum: Sigma & Pi Bonds
- Topic: When looking at at molecule how can I determine when they will form sigma and pi bonds?
- Replies: 3
- Views: 527
Re: When looking at at molecule how can I determine when they will form sigma and pi bonds?
I think all you have to do is determine how many single/double/triple bonds there are. Because there are two double bonds in CO2, there are two sigma and two pi bonds since each double bond has one sigma and one pi bond
- Tue Nov 07, 2017 10:14 pm
- Forum: Lewis Structures
- Topic: Homework 3.33 C
- Replies: 2
- Views: 472
Re: Homework 3.33 C
The central atom is always the atom with the lowest ionization energy
- Tue Nov 07, 2017 9:34 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: The valence electron of Cu and Br
- Replies: 2
- Views: 1154
Re: The valence electron of Cu and Br
Valence electrons are usually in the outermost s or p block. There is one valence electron in Cu (because of 4s^2) and 7 valence electrons in Br (because of 4s^1 4p^5). They could be in the d block though. For example, Fe has 2 (4s^2) or 3 valence electrons (3d^6 because there are two electrons in o...
- Thu Nov 02, 2017 12:31 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: More Polarizable/Polarizing Power
- Replies: 6
- Views: 837
Re: More Polarizable/Polarizing Power
Yes I think that's right
- Thu Nov 02, 2017 12:29 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Energy in Orbitals
- Replies: 2
- Views: 281
Re: Energy in Orbitals
No. Within the same energy level, s<p<d<f
- Tue Oct 24, 2017 11:50 pm
- Forum: Trends in The Periodic Table
- Topic: 2.59
- Replies: 1
- Views: 201
Re: 2.59
They are isoelectronic, but being isoelectronic only means that they have the same amount of electrons, but they still have different properties. Because they have the same number of electrons and Cl- has more protons, the radius for Cl- is the smallest because there are more positive energy attract...
- Tue Oct 24, 2017 11:43 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: #55 part c
- Replies: 1
- Views: 192
Re: #55 part c
5p is higher in energy than 5d, so the p shell in group 5 appears after the transition metals
- Tue Oct 24, 2017 11:37 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: #55 d
- Replies: 3
- Views: 432
Re: #55 d
A full d^10 is more stable than d^9, so the electron configuration is ns^1(n-1)d^10
- Wed Oct 18, 2017 10:22 pm
- Forum: Properties of Electrons
- Topic: 1.57
- Replies: 3
- Views: 475
1.57
1.57 Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0, and 410.2 nm. What is the wavelength of the next line in the series?
How do you set up this problem?
How do you set up this problem?
- Mon Oct 16, 2017 6:43 pm
- Forum: Properties of Electrons
- Topic: Hydrogen Series
- Replies: 4
- Views: 566
Hydrogen Series
In the textbook it said that the Lyman series is in the UV region and the Balmer series in the visible light. But it didn't mention the Paschen nor Brackett series. Do you think we need to know which region they are in?
- Thu Oct 12, 2017 6:42 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3940997
Re: Post All Chemistry Jokes Here
"Susie, these past two years have been amazing, but recently, I just feel like I've been living a half life..."
- Mon Oct 09, 2017 10:11 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Models of Atoms- Question 2.31
- Replies: 4
- Views: 579
Re: Models of Atoms- Question 2.31
I think you are getting n and l mixed up. n is the number of subshells (the number in front of the letter). The reason there's no 2d orbital is that n=2 consists of only 2s and 2p. l describes the shape, which correlates with the letters, meaning that when you try to interpret quantum numbers, you w...
- Thu Oct 05, 2017 9:26 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: E. 23
- Replies: 5
- Views: 1874
Re: E. 23
Oh my gosh I wrote down CuBr3 instead of CuBr2. Thanks!
- Thu Oct 05, 2017 9:05 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: E. 23
- Replies: 5
- Views: 1874
E. 23
Question:
Calculate the amount (in moles) of (a) Cu2 ions in 3.00 g of CuBr2; (b) SO3 molecules in 7.00 x 10^2 mg of SO3; (c) F ions in 25.2 kg of UF6; (d) H2O in 2.00 g of Na2CO3 10H2O.
Hey can someone show me how to set up part a? I seem to be having a brain fart...
Calculate the amount (in moles) of (a) Cu2 ions in 3.00 g of CuBr2; (b) SO3 molecules in 7.00 x 10^2 mg of SO3; (c) F ions in 25.2 kg of UF6; (d) H2O in 2.00 g of Na2CO3 10H2O.
Hey can someone show me how to set up part a? I seem to be having a brain fart...
- Thu Oct 05, 2017 6:01 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant Calculations Post-Module Assessment
- Replies: 2
- Views: 497
Re: Limiting Reactant Calculations Post-Module Assessment
The information about the temperature and pressure isn't really relevant right now