Q: What do you call a tooth in a glass of water?
A: One molar solution.
Search found 30 matches
- Sat Mar 16, 2019 6:44 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591709
- Sat Mar 16, 2019 6:43 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591709
Re: Post All Chemistry Jokes Here
Q: Why does hamburger yield lower energy than steak?
A: Because it's in the ground state.
A: Because it's in the ground state.
- Sat Mar 16, 2019 2:27 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591709
Re: Post All Chemistry Jokes Here
Q: What do you do with a sick chemist?
A: If you can't helium and you can't curium, then you may as well barium
A: If you can't helium and you can't curium, then you may as well barium
- Sat Mar 16, 2019 2:26 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591709
Re: Post All Chemistry Jokes Here
Why do chemists find working with ammonia easy?
Because it’s pretty basic stuff.
Because it’s pretty basic stuff.
- Fri Mar 15, 2019 6:14 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591709
Re: Post All Chemistry Jokes Here
I am trying to think of more chemistry jokes by they all argon...
- Fri Mar 15, 2019 6:13 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3591709
Re: Post All Chemistry Jokes Here
Q: What do you do with a sick chemist?
A. First you try to helium, then you try to curium, but if this fails then you have to barium.
A. First you try to helium, then you try to curium, but if this fails then you have to barium.
- Thu Mar 14, 2019 10:43 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Finding rate constant
- Replies: 2
- Views: 615
Re: Finding rate constant
The production of B is half the rate of the disappearance of A. With stoichiometry from there, the concentration of A must have decreased by 2(0.034 M) = 0.068M. This should be subtracted from the initial concentration of A to determine the concentration after 115s. Then ln([A]/[A0])=-kt should be u...
- Thu Mar 14, 2019 10:36 am
- Forum: General Rate Laws
- Topic: reaction rate(s)?
- Replies: 4
- Views: 725
Re: reaction rate(s)?
A reaction rate compares the change in concentration over time. A rate law relates the rate of reaction to the concentrations of the reactants which are modified by an exponent representing the reaction order.
- Wed Mar 13, 2019 1:09 pm
- Forum: General Rate Laws
- Topic: rate laws and graphs
- Replies: 4
- Views: 553
Re: rate laws and graphs
It is important to know what the integrated rate law for a 0, 1st, and 2nd order looks like when graphed, as well as what would cause them to be a straight line.
- Tue Mar 12, 2019 9:47 am
- Forum: General Rate Laws
- Topic: Zero Order Reactions
- Replies: 4
- Views: 403
Re: Zero Order Reactions
In a zero order reaction the rate does not depend on the concentration. This means the concentration will change linearly compared to time regardless of the rate constant.
- Tue Mar 12, 2019 9:36 am
- Forum: First Order Reactions
- Topic: Doubling the Concentration
- Replies: 4
- Views: 498
Re: Doubling the Concentration
The reaction rate and the order of a reaction are two separate concepts. In rate=k[A], doubling [A] would double the rate of reaction. Increasing the order of the reaction would exponentially increase the rate, as the rate would equal k[A].
- Thu Mar 07, 2019 3:44 pm
- Forum: First Order Reactions
- Topic: First order graph
- Replies: 7
- Views: 871
Re: First order graph
The x-intercept shows how much time time (t) it takes for the natural log of [A] to equal zero, and for [A] to equal zero.
- Wed Mar 06, 2019 11:15 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: kinetics and thermodynamics
- Replies: 4
- Views: 577
Re: kinetics and thermodynamics
Neither is prevalent in controlling a reaction; they each refer to different concepts. Kinetics has to do with the rates of reactions, while thermodynamics focuses on changes in energy during reactions and spontaneity.
- Mon Mar 04, 2019 5:32 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: K
- Replies: 5
- Views: 526
Re: K
This can be seen using ΔG = -RTlnK
When K>1, then lnK is positive, and ΔG is negative.
When K<1, then lnK is negative, and ΔG is positive.
When K>1, then lnK is positive, and ΔG is negative.
When K<1, then lnK is negative, and ΔG is positive.
- Thu Feb 28, 2019 9:17 pm
- Forum: Balancing Redox Reactions
- Topic: oxidizing agent and reducing agent
- Replies: 15
- Views: 1358
Re: oxidizing agent and reducing agent
An oxidizing agent oxidizes another atom, meaning that it gains an electron by removing an electron from another atom. A reducing agent reduces another atom, meaning that it loses an electron giving one to another atom. In essence, oxidizing agents are reduced, and reducing agents are oxidized.
- Thu Feb 28, 2019 4:17 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Finding n
- Replies: 12
- Views: 1126
Re: Finding n
n is the number of electrons being transferred. However, make sure that both half-reactions are balanced before using n, as the number of electrons being transferred should stay consistent in the equation.
- Thu Feb 28, 2019 4:16 pm
- Forum: Balancing Redox Reactions
- Topic: Basic Solutions
- Replies: 5
- Views: 473
Re: Basic Solutions
For basic solutions, H2O is used to balance the hydrogens. Then, when balancing oxygens, OH- should be added, and then H2O may need to be added again if the Hydrogens become unbalanced due to the addition of OH-.
- Thu Feb 28, 2019 4:14 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation state
- Replies: 2
- Views: 288
Re: Oxidation state
Find the total charge on either side of the equation by multiplying the coefficients with the charges. Then electrons should be added to the side with a more positive charge to balance the equation charges.
- Mon Feb 25, 2019 2:10 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Moles in -nFEcell
- Replies: 5
- Views: 650
Re: Moles in -nFEcell
To find n, you must write out both of the half reactions and balance the equations. Once the number of electrons on both sides of the reaction are consistent, this is how many moles should be used in this equation.
- Mon Feb 25, 2019 2:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 6
- Views: 627
Re: Anode and Cathode
In a cell, electrons move from the anode to the cathode. This is because electrons are lost at the anode, where oxidation occurs, and are gained at thee anode, where reduction occurs.
- Mon Feb 25, 2019 9:58 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q=mCdeltaT
- Replies: 15
- Views: 8193
Re: q=mCdeltaT
The units either way should be in Joules because the moles/grams unit will be cancelled in the equation by the specific heat capacity.
- Mon Feb 25, 2019 9:46 am
- Forum: Balancing Redox Reactions
- Topic: Adding OH- and H20 into reactions
- Replies: 3
- Views: 1241
Re: Adding OH- and H20 into reactions
For a basic solution, H2O is added to balance the O atoms in the balanced equation. Next, H2O is added to balance the Hydrogens, and OH- is added to the other side of the equation to make up for the excess Hydrogen atoms.
- Tue Feb 19, 2019 3:40 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Relationship between enthalpy, entropy, and Gibbs
- Replies: 4
- Views: 538
Re: Relationship between enthalpy, entropy, and Gibbs
\Delta G = \Delta H - T \Delta S In order for the reaction to be spontaneous, ΔG = -, so: If ΔH = - , and ΔS = + , the reaction is spontaneous at any temperature. If ΔH = - , and ΔS = - , the reaction is spontaneous at low temperature. If ΔH = + , and ΔS = + , the reaction is spontaneous at high te...
- Wed Feb 13, 2019 9:11 am
- Forum: Phase Changes & Related Calculations
- Topic: 4.18J or 0.38J
- Replies: 8
- Views: 1271
Re: 4.18J or 0.38J
The specific heat capacity of water is either 4.186 J/gK or 75.2 J/molK .
- Fri Feb 08, 2019 9:22 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 3
- Views: 446
Re: Bond Enthalpies
Drawing the Lewis structures of larger molecules can make the calculation much easier in the long run, so I think getting into the habit of drawing them out to get a better visualization of the bond enthalpies makes sense.
- Fri Feb 08, 2019 9:20 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: ΔH
- Replies: 2
- Views: 303
Re: ΔH
ΔH represents the change in energy, so there are different equations based on the information you are provided in the problem (ie. bond enthalpy, enthalpy of vaporization, calorimetry, etc.)
- Fri Feb 08, 2019 9:17 am
- Forum: Phase Changes & Related Calculations
- Topic: Units of enthalpy
- Replies: 5
- Views: 561
Re: Units of enthalpy
ΔH is usually expressed in kJ/mol
- Sun Jan 27, 2019 3:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: Delta H
- Replies: 11
- Views: 2001
Re: Delta H
\Delta H = H_{products} - H_{reactants} , H being enthalpy. If the enthalpy, or total energy, of the products is greater than the energy of the reactants, then ΔH is positive and it is an endothermic reaction. If the energy of the products is less than the energy of the reactants, ΔH is negative an...
- Sun Jan 27, 2019 3:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why are phase changes endothermic?
- Replies: 11
- Views: 1011
Re: Why are phase changes endothermic?
These phase changes all require bonds to be broken which require an input of energy.
- Wed Jan 23, 2019 9:46 am
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic or Exothermic
- Replies: 20
- Views: 2036
Re: Endothermic or Exothermic
Condensation is an exothermic reaction. As the water molecules change phase from gas to liquid, energy is released.