Chem Ch 5-6 Flashcards
(14 cards)
What are 3 ways a salt can be formed?
- a metal reacting with a non-metal
- an acid reacting with a base
- an acid reacting with a metal
What are typical traits of salts?
-often include polyatomic ions
-all are slightly soluble and many are highly soluble
-many will change the pH when dissolved in solution (hydrolysis)
What are the steps to determine if a solution is acidic, basic, or neutral?
- write the dissociation equation
- equilibrium equation
- determine if it’s acidic or basic based on the products
What are some general rules for hydrolysis?
- Alkali metals never hydrolyze water (eg: Na+, K+)
- Anions of strong acids do not hydrolyze water (eg: Cl-, Br-, ClO4-, NO3-, I-, HSO4-)
- Any ion present on the Ka table between strong acids and bases will hydrolyze water
- NH4+ and HSO4- only act as acids
- Metallic ions with a positive charge will act as acids (eg: Fe, Al, Cr)
when will a salt containing a weakly acidic cation and weakly basic anion produce a solution that is acidic, basic, and neutral?
acidic if cation Ka > anion Kb
basic if cation Ka < anion Kb
neutral if cation Ka = anion Kb
What is a buffer?
A solution that resists changes in pH when a small acid of strong acid/base is added to the solution (usually a weak base and its conjugate acid or vice versa)
What are the 4 steps of an acid-base titration?
- write the balanced chemical equation
- using the data provided to determine the number of moles one of the reactant species used
- using the moles determined and the mole ratio from balanced equation to get number of moles of the second reactant consumed
- determine the solution concentration, volume, molar mass, or percent purity
What are acid/base indicators?
Weak acids/bases themselves
What is the NIE when indicator is added to an acid? a base?
acid: H+ + In- = HIn
base: OH- + HIn = H2O + In-
When does the colour change of an indicator occur?
At the transition point when Ka = H3O+
What are acid anhydrides?
-Oxygen containing compounds that react with water to produce acids
-non-metal oxides that tend to be gases
-ex: SO2 + H2O = H2SO3
What are base anhydrides?
-oxygen containing compounds that react with water to produce bases
-metal oxides that tend to be solid
-ex: Na2O + H2O = 2NaOH
What is acid rain?
Normal rain is slightly acidic due to the acid anhydride CO2 in the atmosphere
-when more anhydride gases are present, the more acidic the rain becomes
-limestone deposits (CaCO3) in the ground have a natural buffering effect against acid rain
What can continuous acid rain lead to?
- depletion of limestone deposits
- leaching of mineral deposits
- damage to man-made structures
- damage to plants and animals
