chapter18_mbek



= =MASS ACTION EXPRESSIONS = products ÷ Reactants = [A]s[B]v ÷ [C]u[D]t s, v, u, t are in expontential form If K = 1 the concentration of products and reactants are equal If K > 1 the concentration of products is less than the the concentration of the reactants If K < 1 the concentration of products is greater than the concentration of the reactions At equilibrium, the concentration of NO2 is 0.2M and the concentration of N2O4 is .8M. Find the Keq and tell if the reaction or product is favored K = [0.8M] ÷ [.2M] = 20M; more reactants
 * ONLY INCLUDE GASES AND AQUEOUS COMPOUNDS IN A Keq EQUATION**
 * ex: 2NO2 <=> N2O4 **

**ex: N2 + 3H2 <=> 2NH3** Add H2 equilibrium shifts to the right If the pressure is higher, the reaction shifts to the side with the fewer moles of gas. If the pressure is lower, the reaction will shift to the side with the larger number of moles.
 * Le CHATLIERS PRINCIPLE:** If a system at equilibrium is 'stressed' the system will respond in such a way to minimize the stress

When the pressure increases, the reaction shifts to the side with fewer moles of gas When the pressure decreases, the reaction shifts to the side with greater moles of gas
 * Changing the Pressue of a reaction**

if you add C3OH, the reaction will shift to the right **PRACTICE:** 1. What will happen if you add CO? 2. What will happen if you remove H2?
 * Ex: CH3OH <=> 2H2 + CO2 **

=Solubility Product Equilibria (Ksp) = solubility product constant- the product of the molar concentrations of its ions in a satured solution, each raised to the power that is the coefficient of that ion in the balanced chemical equation

Ksp= [Na+] [Cl] What happens if KCl is added? K+(aq) + Cl-(aq), there is a **common ion** between Cl-(aq)
 * Ex: NaCl(s) <=> Na(aq) + Cl-(aq) **

**Acids and Bases**

**Ex: HCl + H20 => H3O + Cl** HCl is the acid because it lost a proton, and H2O is the base because it gained a proton After losing a proton, the acid species becomes the conjugate base and after gaining a proton, the base species becomes the conjugate acid.
 * **Acids-** anything that can donate a proton
 * **Bases-** anything that accepts a proton

1. NH3 + H20 => NH4+ + OH- What is the acid and what is the base? 2. CH3COOH + NH2- => NH3 + CH3COO- What is the acid and what is the base? What is the conjugate acid and the conjugate base?
 * PRACTICE:**

H-Cl Hydrogen is "loose" because it is 2.1 compared to Cl's 3.0, making it a stronger acid
 * Predicting Acidity**

2 Scales: 1. Ka/Pka 2. pH If Ka is large, the acid is stronger If Ka is smaller, the acid is weaker
 * Acid Strength**

pKa= - log Ka THE LARGER THE Ka VALUE= WEAKER THE SMALLER THE Ka VALUE= STRONGER

1. Find the pka of an acid whose ka is 1.8 x 10E-5 2. Find the pka of an acid whose ka is 2.9 x 10E-15
 * PRACTICE:**

PH= - log
 * Ex: For H20, pH= - log (1 x 10E-7) = 7 **


 * PH SCALE**

**Nuetralizing Acids (or bases)** - an acid is nuetralized when the color disapears - to figure out the strength of an acid use the equation M1 V1 = M2 V2

1. Homeostasis: your bodie's equilibrium 2. Amphoteric: capable of acting as an acid or a base 3. Vinegar is an acetic acid 4. Acidus refers to sour and bases refers to bitter 5. H30+ makes the acid stronger 6. Titration- measuring amount of base needed to go into nuetralize

ANSWERS (in order) 1. shift to the left 2. shift to the right

1. NH3 is the base and H20 is the acid 2. CH3COOH is the acid, NH3 is the conjugate acid NH2 is the base, CH3COO is the conjugate base

1. pka = 4.74 2. pka = 14. 5