CHEMISTRY COMMUNITY

Philipp_V_Dis1K

1/16= (1/2)^4, so that means 4 times the halflife. 1/4=(1/2)^2 so 2 times the halflife. for part c, use the second order reaction

Philipp_V_Dis1K

the rate depends on the reactants initially, over time the products will decompose back into reactants as they reach equilibrium, but initially it only matters on reactants (assuming temperature and all other factors are constant)

Philipp_V_Dis1K

if you use the formula of 1 over the molar coefficient one can find the change in [a] as a ratio of change of [b]

Philipp_V_Dis1K

If you change the concentration of reactant and the amount of product changes by the same amount, n is 1. If product changes by a higher value than your reactant, take the value the reactant was changed by and see to what power it must be raised by to get the same value as the product

Philipp_V_Dis1K

K depends on the order of the reaction, because the concentrations of the reactants are raised to different powers.

Philipp_V_Dis1K

Depending on the order of said reaction one can figure out k and the concentration of the products at certain times

Philipp_V_Dis1K

usually one can look at the amount of electrons in the redox half reaction, which shows how many moles of electrons were used.

Philipp_V_Dis1K

a positive E means that the reaction will create energy, "exothermic" in a sense, with no need to put in heat to start the reaction. This is the opposite for negative E values, which are "endothermic" and require energy for the reaction to proceed

Philipp_V_Dis1K

redox reactions are net ionic, meaning the ions that do not change charge in the reaction are left out

Philipp_V_Dis1K

The reaction will theoretically create the same voltage at all times, this just means that it is always the same so there is no difference in how we calculate it

Philipp_V_Dis1K

The E value does not depend on the right or left, it is on the E potential of the cathode and anode.

Philipp_V_Dis1K

What happens in an electric current and cell when there is no transfer of extra ions from solution to solution?

Philipp_V_Dis1K

There are several molecules that are fairly constant in their oxidation state, such as Oxygen with -2 or Hydrogen with +1. Most of the metals can go either way.

Philipp_V_Dis1K

Entropy is the amount of chaos in the system, while enthalpy is the heat released

Philipp_V_Dis1K

The reaction is "at completion" so there is nothing spontaneous to drive the reaction forward or backward

Philipp_V_Dis1K

can someone explain how to do #5

Philipp_V_Dis1K

In this question it asks "what is the total entropy change when 40kJ of heat are transferred from a large reservoir at 800K to one at 200K.
Why wouldn't the total entropy change either be zero, because one lost entropy and the other gained it, or be (q/T)?

Philipp_V_Dis1K

They can be both, reversible means that the external pressure is equal to the pressure of the gas and slowly increases/decreases with the gas pressure according to if it is expanding or being compressed, respectively. A irreversible reaction is one where the external pressure is constant, and one do...

Philipp_V_Dis1K

Isothermic means constant temperature, isometric means same chemical formula but different arrangement in 3D space

Philipp_V_Dis1K

Usually one assumes that a certain amount of energy (joules) is released or used up during a reaction of 1 mole. Therefore it can be J/mol or kJ/mol

Philipp_V_Dis1K

Let's look at the reaction of 2H2O2->2H2O + O2
Even though hydrogen peroxide is broken up into water an oxygen, the O2 is in it's natural or most occuring form and therefore doesn't take energy or release energy to be created

Philipp_V_Dis1K

An isolated system's internal energy stays constant or increases, so it's unlikely for it to have a changing volume

Philipp_V_Dis1K

The enthalpy of reaction is made up of the separate enthalpies of formation for the molecules involved

Philipp_V_Dis1K

Exothermic, one can look at the reverse, which is endothermic, when one sweats and the body heat is used up to vaporize the sweat.

Philipp_V_Dis1K

Usually acids have an extra H on either the end or beginning of the chemical formula, and bases have an OH group.

Philipp_V_Dis1K

this only works with distilled water, where the water molecules do not have something to bond around in their crystalline pattern, however when one shakes or disturbs the water, they molecules are jostled into place and freeze.

Philipp_V_Dis1K

Net ionics just takes the reactants and only leaves the molecules/ions that changed from one reaction to the other.

Philipp_V_Dis1K

Bypassing the quadratic equation because when on the bottom of the (x^2)/(concentration-x), the x, or change in concentration, is so small that the concentration is basically untouched and it is needless to use it. Therefore the equation becomes (x^2)/concentration. Then it's very easy to solve for ...

Philipp_V_Dis1K

K is the letter that denotes an equilibrium reactions quotient, the c is just denoting it's a non-acid /base reaction, a for acid, b for base.

Philipp_V_Dis1K

Since they have the same formula, it is just a view of the value of the products and reactants and using this value to see how it applies to the equilibrium constant.

Philipp_V_Dis1K

Since K values smaller than 10^-3 are considered small, and large ones are greater than 10^3, what do the values between 10^-3 and 10^3 represent?

Philipp_V_Dis1K

One could use the van der waals equation to see the difference between real and ideal gases.

CHEMISTRY COMMUNITY

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