CHEMISTRY COMMUNITY

varunhariharan

Q: What do you call a tooth in a glass of water?
A: One molar solution.

varunhariharan

Q: Why does hamburger yield lower energy than steak?
A: Because it's in the ground state.

varunhariharan

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

varunhariharan

Why do chemists find working with ammonia easy?
Because it’s pretty basic stuff.

varunhariharan

I am trying to think of more chemistry jokes by they all argon...

varunhariharan

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.

varunhariharan

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...

varunhariharan

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.

varunhariharan

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.

varunhariharan

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.

varunhariharan

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] $^{2}$ .

varunhariharan

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.

varunhariharan

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.

varunhariharan

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.

varunhariharan

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.

varunhariharan

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.

varunhariharan

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-.

varunhariharan

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.

varunhariharan

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.

varunhariharan

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.

varunhariharan

The units either way should be in Joules because the moles/grams unit will be cancelled in the equation by the specific heat capacity.

varunhariharan

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.

varunhariharan

\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...

varunhariharan

The specific heat capacity of water is either 4.186 J/gK or 75.2 J/molK .

varunhariharan

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.

varunhariharan

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.)

varunhariharan

ΔH is usually expressed in kJ/mol

varunhariharan

\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...

varunhariharan

These phase changes all require bonds to be broken which require an input of energy.

varunhariharan

Condensation is an exothermic reaction. As the water molecules change phase from gas to liquid, energy is released.

CHEMISTRY COMMUNITY

Search found 30 matches

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: Finding rate constant

Re: reaction rate(s)?

Re: rate laws and graphs

Re: Zero Order Reactions

Re: Doubling the Concentration

Re: First order graph

Re: kinetics and thermodynamics

Re: K

Re: oxidizing agent and reducing agent

Re: Finding n

Re: Basic Solutions

Re: Oxidation state

Re: Moles in -nFEcell

Re: Anode and Cathode

Re: q=mCdeltaT

Re: Adding OH- and H20 into reactions

Re: Relationship between enthalpy, entropy, and Gibbs

Re: 4.18J or 0.38J

Re: Bond Enthalpies

Re: ΔH

Re: Units of enthalpy

Re: Delta H

Re: Why are phase changes endothermic?

Re: Endothermic or Exothermic