Chemistry Exam #2

Molarity

moles of solute / liters of solution

Dilution formula

M1V1 = M2V2

Always Soluble group

Group 1 ions (NH4+, NO3-, C2H3O2-)

Usually soluble group

Cl-, Br-, I-

When do usually soluble ions become insoluble?

When paired with Ag+, Pb2+, Hg2 2+

Usually insoluble group

CO3 2-, PO4 3-, S2-, OH-

When do usually insoluble become soluble?

When paired with a group 1 ion (NH4+, NO3-, C2H3O2-)

Strong electrolytes

tons of ions, NaCl, HCl, KOH

Weak electrolytes

few ions, Hf

Nonelectrolytes

No ions, sugar and alcohol

Strong acids

HCl, HBr, HI, HNO3, HClO3, H2SO4

How to predict a precipitate?

Exchange ions

Write products

Solubility rules

Acid-base reactions / Neutralization reactions

Acid + Base → Salt + water

Titrant

Known concentration of solution

Equivalence point

acid completely reacts with base

Indicator

change in color in the equivalence point

Redox reactions (oxidation/reduction reactions)

Oxidizing agents → gets reduced

Reduction agents → gets oxidized

Oxidation

loses electrons

Reduction

Gains electrons

Oxidation numbers

Usually equal the charge of the element (O² = 2)

Limiting reagent is ________________

smallest product amount

Percent yield

Actual yield / Theoretical yield x 100%

Energy

E = the ability to do work

Endothermic

gains heat

Exothermic

loses heat

Thermochemistry

System - being studied

Surroundings - around the system

Heat

energy transferred due to temperature

Work

Energy transferred by force

q equals

Heat

w equals

work

Specific heat

amount of heat to raise 1 g by 1 degree Celsius

Specific heat units

Joules / g x mol

Internal energy (deltaU)

q+w

delta T

change in temperature

Specific heat equation

q=mc deltaT

Heat capacity

The amount of heat needed to raise an object by 1 degree Celsius

Heat capacity equation

q=C deltaT

C equals

joules / degrees Celsius

Calorimetry

q lost = q gained

Hess’s Law

Flipping the reactants and products and adjusting the heat accordingly

H equals

change in heat energy

Enthalpy

delta H = H products - H reactants

Enthalpy in formation

delta H degrees final = 0

M equals

mol / L

m equals

mass

V equals

liters

q equals

Joules

C equals

J / g times degrees Celsius

delta T equals

T final - T initial

w equals

joules

Calculate enthalpy

q = m delta H

delta H equals

KJ / mol

How to calculate moles?

moles / molar mass