Search found 49 matches
- Sat Mar 17, 2018 1:31 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Determining Slow Step
- Replies: 2
- Views: 13142
Determining Slow Step
Is it possible to determine the slow step, rate determining step, of a mechanism from the individual steps? If the slow and fast steps are not explicitly stated, is there a way to figure out which is which? Will we need to do this or will it always be given?
- Sat Mar 17, 2018 1:19 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Steady State Approximation Vs Pre Equilibrium
- Replies: 2
- Views: 881
Steady State Approximation Vs Pre Equilibrium
How do we differentiate whether to use the steady state approximation method versus the pre equilibrium approach to construct the overall rate law from a mechanism?
- Sun Mar 11, 2018 10:36 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890178
Re: Post All Chemistry Jokes Here
A photon checks into a hotel and is asked if he needs any help with his luggage. He says, "No, I'm traveling light."
- Sun Mar 11, 2018 10:17 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890178
- Sun Mar 11, 2018 10:15 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890178
- Sun Mar 11, 2018 10:14 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890178
Re: Post All Chemistry Jokes Here
Don't trust atoms, they make up everything.
- Mon Mar 05, 2018 9:36 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Determining overall rate order
- Replies: 3
- Views: 577
Determining overall rate order
Are only the rate orders of reactants relevant in the overall rate order? Do rate orders of products even exist, or only in the reverse reactions?
- Mon Mar 05, 2018 9:33 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Example 15.2
- Replies: 1
- Views: 301
Example 15.2
When given a chart with multiple experiments to decide how initial rate of consumption varies as concentration of reactants changes, does it matter which experimental data/ concentrations to put back into the general rate law once you've found all the reaction orders for the reactants?
- Mon Mar 05, 2018 9:28 pm
- Forum: Zero Order Reactions
- Topic: Zero order integrated rate law
- Replies: 1
- Views: 449
Zero order integrated rate law
Can someone integrate the rate law for 0 order reactions step by step? Im having trouble visualizing how it gets to [A]o-[A]=kt
- Sun Feb 25, 2018 10:41 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Midterm Q3A
- Replies: 2
- Views: 578
Midterm Q3A
Calculate the heat (kj) that must be supplied to a 1.4 kg iron pot containing 1.2 kg water in order to raise its temperature from 22 degrees celsius to the boiling point of water. Assume no water evaporates. What percentage of the water was used for heating the water? What are the steps for solving ...
- Sun Feb 25, 2018 10:29 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Midterm Q5
- Replies: 2
- Views: 525
Midterm Q5
A system undergoes a two-step process. In step one, it expands adiabatically from 1.00 L to 2.56L against an external pressure of 1.00 atm. In step 2, it releases 73J of heat at 1.00 atm as it returns to the original internal energy. Find the volume of the system.
How do I solve this problem?
How do I solve this problem?
- Sun Feb 25, 2018 10:26 pm
- Forum: Calculating Work of Expansion
- Topic: Midterm 4A
- Replies: 3
- Views: 481
Midterm 4A
A piston containing .10 mol of nitrogen gas at 298k has an initial volume of 2.24 L and undergoes an expansion against .5atm external pressure until its volume doubles. Calculate the work involved in Joules.
Which work equation do we use for this and why?
Which work equation do we use for this and why?
- Sun Feb 18, 2018 7:26 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reaction
- Replies: 3
- Views: 456
Re: Half Reaction
I don't think so either because in full reactions there should be no free electrons, but in half reactions the electrons and H+ molecules should be included with the compounds
- Sun Feb 18, 2018 7:22 pm
- Forum: Balancing Redox Reactions
- Topic: Basic conditions
- Replies: 3
- Views: 506
Re: Basic conditions
If the equation is being balanced in a basic solution, through the addition of one more step, the appropriate number of OH- must be added to turn the remaining H+ into water molecules
- Sun Feb 18, 2018 7:16 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 4
- Views: 771
Re: Balancing Redox Reactions
I believe you don't use H3O+ because then it would unbalance the oxygens in the reaction
- Sun Feb 11, 2018 9:43 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Gas Constant, R
- Replies: 6
- Views: 838
Gas Constant, R
Will we ever need to use one of the other gas constants given on the constants/equations sheet for the midterm or only the 8.314 one?
- Sun Feb 11, 2018 9:37 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Comparing Molar Entropies
- Replies: 2
- Views: 1480
Comparing Molar Entropies
What do we look for when deciding which has higher molar entropy?
For example, why can we say that Lead has a higher molar entropy than Carbon?
For example, why can we say that Lead has a higher molar entropy than Carbon?
- Sun Feb 11, 2018 9:33 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Practice Midterm 3A
- Replies: 3
- Views: 511
Practice Midterm 3A
How do we know to whether to use Cv or Cp when calculating with the nClnT2/T1 equation?
- Sun Feb 04, 2018 10:22 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Transfer Test 1 Concept Question
- Replies: 2
- Views: 458
Heat Transfer Test 1 Concept Question
Why is heat being transferred when a balloon filled with gas is expanded to a larger volume and lower pressure while maintaining the same temperature?
- Sun Feb 04, 2018 10:19 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open, closed, or isolated test 1 question
- Replies: 10
- Views: 1662
Open, closed, or isolated test 1 question
Is a 20mL vial with an organic solvent open, closed, or isolated and why?
- Sun Feb 04, 2018 10:17 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sig Figs
- Replies: 6
- Views: 756
Sig Figs
Are sig figs important when doing these calculations?
- Sun Jan 28, 2018 9:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic or Exothermic
- Replies: 20
- Views: 2070
Endothermic or Exothermic
Is condensation endothermic or exothermic and why?
- Sun Jan 28, 2018 9:34 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open, closed, or isolated [ENDORSED]
- Replies: 3
- Views: 1062
Open, closed, or isolated [ENDORSED]
Is the universe an open, closed, or isolated system and why?
- Tue Jan 23, 2018 12:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 914
Hess's Law
When using Hess's law to calculate enthalpy, can you eliminate a molecule within the same equation? For example, if one of the equations has CO2 on both sides can they be crossed out?
- Sun Jan 21, 2018 6:47 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity vs Specific Heat Capacity
- Replies: 2
- Views: 287
Heat Capacity vs Specific Heat Capacity
Can someone clarify the difference between Heat Capacity and Specific Heat Capacity and how they relate to extensive and intensive properties?
- Sun Jan 21, 2018 6:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heating Curve Calculation Confusion
- Replies: 3
- Views: 357
Heating Curve Calculation Confusion
If there is a question where we have to convert ice to water vapor, do we have to use MCdeltaT twice to account for the temp change between the solid to melting point and also from the melting point to the boiling point? So would it be MCdeltaT+phase change+MCdeltaT+phase change
- Sun Jan 21, 2018 5:43 pm
- Forum: Phase Changes & Related Calculations
- Topic: Work Equation
- Replies: 3
- Views: 252
Work Equation
Where/what does the negative in the w=-PdeltaV (work equation) come from and signify?
- Sun Jan 14, 2018 8:52 pm
- Forum: Phase Changes & Related Calculations
- Topic: Exercise 8.31
- Replies: 3
- Views: 356
Re: Exercise 8.31
Chem_Mod wrote:The equation used for calculating heat released is q=mCΔT. Since we are told that Kr behaves as an ideal gas, we can use the specific heat capacity for ideal gases at constant pressure (Cp=5/2R) and at constant volume (Cv=3/2R).
Where does the 5/2R come from?
- Sun Jan 14, 2018 8:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy Formation
- Replies: 2
- Views: 259
Standard Enthalpy Formation
Can someone explain what Standard Enthalpy Formation is and why is it 0 for elements in their most stable form?
- Sun Jan 14, 2018 8:35 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar Heat Capacity
- Replies: 4
- Views: 195
Molar Heat Capacity
Does an increase in number of elements in a molecule correlate to a higher molar heat capacity? Or how do we know which molecule will have a higher molar heat capacity?
- Thu Dec 07, 2017 6:53 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Lewis Structure of Coordination Compounds
- Replies: 1
- Views: 260
Lewis Structure of Coordination Compounds
When drawing the lewis structure of coordination compounds can we leave the ligands together as one branch off of the the central atom, or do we need to break down the structures of the ligands too? For example can I write NH3 together or do I need to break it down into its four bonds?
- Thu Dec 07, 2017 6:44 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Dentates
- Replies: 4
- Views: 591
Dentates
Are (COO) and (N)'s the main things to look for in a coordination compound to find out if it is monodentate/bidentate/etc? Are there any others?
- Thu Dec 07, 2017 6:36 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Change in concentration
- Replies: 2
- Views: 212
Change in concentration
Will how the pressure is changing always be given? For example, will it always tell us that it is a result of change in volume or other?
- Thu Dec 07, 2017 6:12 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Relationship between Kpa and Ph
- Replies: 3
- Views: 1082
Relationship between Kpa and Ph
Is there a direct relationship between Ka and pH, or Kb and pOH?/
- Thu Dec 07, 2017 6:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Finding Q and which way the reaction shifts
- Replies: 1
- Views: 266
Finding Q and which way the reaction shifts
When given a problem asking to find the equilibrium concentrations of multiple compounds involved in a reaction, and when all the initial molarities and a Kc value are given, how do you know which compounds to make the reactants and products to find Q? We need to know Q to know which way the reactio...
- Mon Nov 27, 2017 12:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs Nonpolar [ENDORSED]
- Replies: 2
- Views: 282
Polar vs Nonpolar [ENDORSED]
What is the best way to determine if the dipole moments will cancel out and make the molecule non polar?
- Mon Nov 27, 2017 12:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs and naming shape
- Replies: 2
- Views: 273
Lone pairs and naming shape
Is the lone pair taken into account when naming the shape of a molecule? Why or why not?
- Sun Nov 19, 2017 5:49 pm
- Forum: DeBroglie Equation
- Topic: Midterm Question: wavelike properties
- Replies: 6
- Views: 781
Midterm Question: wavelike properties
What does it mean to have measurable wavelike properties?
- Sun Nov 19, 2017 5:44 pm
- Forum: Lewis Structures
- Topic: Midterm Question: Lewis Structure for HOCO [ENDORSED]
- Replies: 6
- Views: 2235
Midterm Question: Lewis Structure for HOCO [ENDORSED]
What does this lewis structure look like? I know that it is a radical but do not know how to draw it.
- Sun Nov 12, 2017 9:19 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Most Favorable Formal Charge
- Replies: 5
- Views: 3093
Most Favorable Formal Charge
When it is impossible that all elements can have 0 formal charge, does it matter which ones get the formal charge? Should it be the central element or the outside ones?
- Sun Nov 12, 2017 9:14 pm
- Forum: Octet Exceptions
- Topic: Expanded Octet
- Replies: 4
- Views: 648
Expanded Octet
How do we know when it is best to give an element an expanded octet?
- Fri Nov 03, 2017 11:08 am
- Forum: Ionic & Covalent Bonds
- Topic: Covalent/ Ionic Bond
- Replies: 5
- Views: 865
Covalent/ Ionic Bond
How do we determine it two elements will form and ionic or covalent bond?
- Fri Nov 03, 2017 11:05 am
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity Trend
- Replies: 1
- Views: 1893
Electron Affinity Trend
Are there exceptions to the electron affinity trend in the periodic table?
- Thu Oct 26, 2017 8:51 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: d and s blocks
- Replies: 16
- Views: 2222
d and s blocks
Why is the d block written before the s block? Could they be interchangeable or it has to be that way?
- Thu Oct 26, 2017 8:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Orbital Shape
- Replies: 3
- Views: 514
Orbital Shape
Do we need to know the shape of the different orbitals for the test/ midterm?
- Fri Oct 13, 2017 8:03 pm
- Forum: Properties of Electrons
- Topic: Energy Level Change
- Replies: 5
- Views: 751
Energy Level Change
Does an excited electron always drop back down to level 1 to become most stable? Or is it possible that it will drop to a level higher than one?
- Fri Oct 13, 2017 8:01 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Balmer/Lyman Series [ENDORSED]
- Replies: 7
- Views: 962
Balmer/Lyman Series [ENDORSED]
What are the significances of these series? What do we need to know about them?
- Fri Oct 06, 2017 2:43 pm
- Forum: Balancing Chemical Reactions
- Topic: Equation Notation [ENDORSED]
- Replies: 2
- Views: 536
Equation Notation [ENDORSED]
When writing chemical equations, why are some atoms paired together in parenthesis with a subscript?
For example Ca5(PO4)3OH
Does this mean that the 3 applies to all elements in the parenthesis?
For example Ca5(PO4)3OH
Does this mean that the 3 applies to all elements in the parenthesis?
- Fri Oct 06, 2017 2:33 pm
- Forum: SI Units, Unit Conversions
- Topic: Base Units
- Replies: 6
- Views: 802
Re: Base Units
You only have to convert to base units if they ask for it in the answer. Also, some equations will require you to convert before solving such as the molarity equation because you have to divide by liters.