CH 101 chapter 8

solution

a homogenous mixture

solute

minor component of a solution- the substance being dissolved

solvent

the major component of a solution- the substance that dissolves the solute

dilute solution

has a small amount of solute compared to solvent

concentrated solutions

have a large amount of solute compared to solvent

molarity

amount of solute in moles/volume of solution in liters

common way to express concentration of solutions

dilution

when a new solution is prepared from a stock solution (more concentrated solution)

concentration and volume relationship

c1v1 = c2v2 or m1v1 = m2v2 (molarity) - relates stock and new solutions

molarity, volume, and moles relationship

molarity of solution A * volume of solution A (L) = # of moles of solution A

salt solutions

ionic compounds (metals and nonmetals) dissolved in water form salt solutions

electrolytes

materials that dissolve in water to form a solution that will conduct electricity

strong electrolytes

ionic substances that completely dissociate into ions when they dissolve in water

acids and bases

compounds that dissociate into their ions when dissolved in water

• depending on acid or base, dissociation can be complete (strong acid/base) or partial (weak acid/base)

nonelectrolyte solutions

materials that dissolve in water to form a solution that will not conduct electricity (sugar solutions) - most molecular compounds (except acids and bases) dissolve in water as intact molecules

soluble

compounds can dissolve in water

insoluble

compounds that cannot dissolve in water

compounds that are generally soluble

Li+, Na+, K+, NH₄+, NO₃^-, C₂H₃O₂^-, Cl-, Br-, I-, SO₄^2-

soluble with no exceptions

Li+, Na+, K+, NH₄+, NO₃^-, C₂H₃O₂^-

solubility exceptions for Cl-, Br-, I-

insoluble when they pair with Ag+, Hg₂²⁺, or Pb²⁺

solubility exceptions for SO₄^2-

insoluble when paired with Sr²⁺, Ba²⁺, Pb²⁺, Ag⁺, or Ca²⁺

compounds that are generally insoluble

OH-, S^2-, CO₃^2-, PO₄^3-

solubility exceptions for OH- and S^2-

soluble when paired with Li+, Na+, K+, NH₄+

when S^2- pairs with Ca²⁺, Sr²⁺, or Ba²⁺, result is soluble

when OH- pairs with Ca²⁺, Sr²⁺, or Ba²⁺, result is slightly soluble

solubility exceptions for CO₃^2- and PO₄^3-

soluble when paired with Li+, Na+, K+, or NH₄+

precipitation reactions

reactions between aqueous solutions of ionic compounds produce an ionic compound that is insoluble (solid; known as the precipitate)

molecular equation

an equation showing the complete neutral formula for each compound in the aqueous reaction as if they existed as molecules

complete ionic equations

equations that describe the materials structure when dissolved- shows molecular equation with all elements written as ions

ionic equation rules

aqueous strong electrolytes are written as ions- soluble salts, strong acids/bases

insoluble substances, weak electrolytes, and nonelectrolytes are written in molecular form

• solids, liquids, and gases are not dissociated and remain in form

net ionic equation

treats the ionic equation arrow as an equal sign, cancelling out ions that appear on both sides

acids

molecular compounds that form H+ when dissolved in water

composed of hydrogen- usually written first in the formula with one or more nonmetals written second

polyprotic acids

have more than 1 hydrogen so can donate more than 1 proton- naming uses prefixes (ex an H₂ acid is a diprotic acid)

base

a substance that produces OH^- ions in an aqueous solution

binary acids

have a H+ cation and a nonmetal anion- two elements

oxyacids

have H+ cation and a polyatomic anion- contain oxygen

naming binary acids

1. write hydro- prefix

2. follow with nonmetal name

3. change the ending on nonmetal to -ic

4. follow with the word acid

naming oxyacids

if a polyatomic ion name ends in -ate, change the ending to an -ic suffix

if a polyatomic ion name ends in -ite, change the ending to an -ous suffix

write the word acid at the end of all names

acid-base reaction

known as a neutralization reaction- acid and base react to form water and a salt

titration

a substance in a solution of known concentration is reacted with another substance in a solution of unknown solution

• known solution (titrant) is added slowly to a flask with unknown solution using a buret

indicator

chemical added in acid/base titrations that changes color when the solution undergoes large changes in acidity/alkalinity

reaction endpoint

when color of indicator changes

• indicator selected so endpoint is reached when the # of moles H+ equals the # of moles OH-

  • known as the equivalence point

gas evolution reaction

some reactions form a gas directly from ion exchange

other reactions form a gas by decomposition of one of the ion exchange products into a gas and water

sulfides + gas evolution reactions

no intermediate product- forms H₂S directly from ion exchange

carbonates and bicarbonates in gas evolution reactions

form H₂CO₃ as an intermediate product- leaves CO₂ and water as products

sulfites and bisulfites in gas evolution reactions

intermediate product is H₂SO₃ - forms SO₂ and water

ammonium in gas evolution reactions

intermediate product is NH₄OH - forms NH₃ and water

oxidation-reduction reactions/redox reactions

reactions in which electrons are transferred from one reactant to another

• atoms that lose electrons are oxidized (oxidation)

• atoms that gain electrons are reduced (reduction)

• many redox reactions involve reaction of substance with oxygen

oxidation states

each element in a reaction is assigned a number to help determine electron flow in a reaction

• NOT ion charges, simply imaginary charges assigned based on a set of rules

rules for oxidation states

must be followed in order of priority!!

1. free elements have an oxidation state of 0

2. monoatomic ions have an oxidation state equal to their charge

3. sum of oxidation states of all the atoms in a compound = 0

   1. sum of all the oxidation states in a polyatomic ion must equal ion charge

4. group I metals have an oxidation state of +1, group II have oxidation states of +2

5. in their compounds, nonmetals have oxidation states according to the following (in order of priority):

   1. Fluorine = -1

   2. Hydrogen = +1

   3. Oxygen = -2

   4. group 7A = -1

   5. group 6A = -2

   6. group 5a = -3

reducing agent

the element being oxidized in a redox reaction

oxidizing agent

the element being reduced in a redox reaction

oxidation/reduction and oxidation states

oxidation is an increase in oxidation state and reduction is a decrease in oxidation state