CH101 Exam 3

What are the two categories of energetics

thermodynamics and kinetics

What is thermodynamics

the energy difference between the reactants and the products, Ei vs Ef

What is kinetics

study of the path of the reactants to the products

What are the two measurements of thermodynamics

enthalpy and enthropy

What is enthalpy and what is its symbol

H, heat content of reaction when pressure is constant

When the enthalpy of an reaction is negative is it exothermic or endothermic

exothermic

When enthalpy is postive is the reaction exothermic or endothermic

endothermic

Is the reaction enpthaplically favorable when H is postive or negative

negative

Are the bonds stronger when the subtances are at a higher energy or lower energy

lower energy

how is the change in H calaculated

sum of bonds broken - sum of bonds formed

What is the thermodynamic equation

Energy of the universe = energy of the system + energy of the surroundings

What is the law about thermodynamics

energy is never created or destroyed but converted

What is entropy and what is its symbol

S, the amount of disorder present in a system

What does a low entropy look like

ordered system, energy concentrated

What does high entropy look like

disorder system, energy spread out

Is an reaction entropically favored when its positive or negative

positive

Is the favorably of enthapy and entropy directly or inversely related

inveresly related

How is the entropy determined

the states of matter of the substances and the number of molecules present on each side of the equation

What is gibbs free energy equation

G= H -TS

Is G favored when its positive or negative

negative

Is G spontaneous when its postive

no, postive G is non-spontaneous

What makes a reaction spontaneous

When products are lower in energy than the reactants

When both H and S are negative is the reaction spontaneous at low temperatures

yes

When both H and S are negative is the reaction spontaneous at high temperatures

no

When both H and S are postive is the reaction spontaneous at low temperatures

no

When both H and S are positive is the reaction spontaneous at high temperatures

yes

What does a large Ea determine about a reaction

slower reaction, needs more energy

What does a small Ea determine about a reaction

fast reaction, less energy needed

What are the three ways to change the speed of a chemical equation(increase Ea)

increase temperature, increase concentration, use a catalyst

What is cataylst

molecular matchmaker, increases moleuclar collisions

What is an equilibirum

forward rate = reverse rate when the reactants and products are constant

What is the equation of equilibrium

Keq= [products]/[reactants] (ceofficents raised to the power in equation)

What units are used in the equalibrium equation

solutions= mol/L, gases= mol/L or atm

What does a Keq»1 mean

products favored, extensive equations

What is keq«1 mean

reactants favored, not favorable

What does keq= 1

comparable concentrations

If Ef > Ei then what is G and Keq

G is positive, Keq «1

If Ef = Ei then what is G and Keq

G is O, Keq = 1

If Ef < Ei then what is G and Keq

G is negative, Keq » 1

What is Le Chateliers Principle

At equilibrium, if a system is disturbed by changing its condition the system will counteract that change to restablish equilibrium(scale)

If a reaction is endothermic, is the addition of temperature added to the reactant side of the equation or the product side according to Le Chatelier’s principle

reactant side

If a reaction is exothermic, is the addition of temperature added to the reactant side of the equation or the product side according to Le Chatelier’s principle

product side

What is the Bronsted acid

H+/ proton donor

What is a Bronsted base

H+/ proton acceptor

What does conjungate mean

it is a Bronsted base or acid that forms

How does the Lewis definition of acids and bases compare to the Bronsted definition of acids and bases

All Bronsted acids and bases are Lewis acids and base but not all Lewis acids and bases are Bronsted

What are the mechanism arrows of a Bronsted acid equation

arrows that start at on electron source to show their movement

What is a strong acid

large Ka, more reactive, high energy, unstable

What is a weak acid

small Ka, less reactive, low energy, stable

What is pKa

-log(Ka), helps show acid strength on number line

Does a stable conjugate base have a strong or weak parent acid

strong parent acid

What are the three steps to assessing the relative acidity of an acid

(Looking at conjungate base) 1) atom holding - (same row=electronegativity, same column= atom radius) 2) is there resonance structures? yes=more stable 3) consider - donating/ withdrawing groups (lot of dipole arrows= more stable)

The stronger the acid…

the weaker the base

A weak acid has a base high or low in energy

high