Week 4 (Acids, Bases, Salts) Flashcards
Acid
-Arrhenius
-a chemical that, when dissolved in water, will increases the concentration of H+ ions
-changes litmus paper to red
-reacts with carbonates to form CO2
-reacts with active metals to form H2
-pH < 7.00
Active metals
very electropositive metals
Base
-Arrhenius
-a chemical that, when dissolved in water, will increase the concentration of OH- ions
-causes litmus paper to turn blue
-reacts with many metal ions to form precipitates
-pH > 7.00
Neutralization
-an acid reacts with a base to form a salt (ex. HCl + NaOH -> NaCl + H2O)
-cation comes from base, anion comes from acid
-not all salt solutions are neutral
Bronsted-Lowry base/acid definition
-Acid: a substance that can donate a proton to another substance (ex. acid donates H+ to water to form H3O)
-Base: a substance that can accept a proton from another substance (ex. bases accept H+ cation from an acid (OH + H = H2O))
Lewis base/acid definition
-Acid: electron pair acceptor
-Base: electron pair donor
Identifying acids by chemical formulas
-HnA
–(A(-n) is a simple anion (HCl, H2S, HCN, HI) or a polyatomic anion (H2SO4, HNO3, HClO))
-COOH
–(Organic acid (CH3COOH))
Identifying bases by chemical formulas
-M(OH)m
–(M(m+) is a metal cation (KOH, Ca(COH)2))
-R3N
–(Ammonia or an organic amine where R can be H or alkyl group (-CH3, -CH2CH3, etc.))
How are bases formed?
metal oxides (base anhydrides) dissolve in water to form hydroxides
(ex. Na2O + H2O -> 2 NaOH)
How are acids formed?
non-metal oxides (acid anhydrides) dissolve in water to form acids
(ex. SO3 + H2O -> H2SO4)
acid anhydrides
non-metal oxides that form acids when they react with water
Oxide
a chemical compound containing at least one oxygen atom and one other element in its chemical formula (N2O, CaO, SiO3, etc)
base anhydride
metal oxide that forms base when it reacts with water
Strong acid
-completely dissociate in water
-strong electrolyte
- HCl, HBr, HI, HClO3, H2SO4, HNO3
Weak acid
-only partially dissociate in water
-weak electrolyte
- HClO2, HClO, H2SO3, HNO3
-most organic acids (R-COOH)
Strong base
-completely dissociate in water
-group 1/group 2 metal hydroxides (ex. NaOH)
Weak base
-only partially disassociate in water (ex. NH3)
pH scale
-ionization of water is point of reference to tell us if something is an acid or base
Neutral solution H+ to OH- ratio
[H+]=[OH-]
Acidic solution H+ to OH- ratio
[H+]>[OH-]
Basic solution H+ to OH- ratio
[H+]<[OH-]
p-scale
-calculates number that describes acid/base
-pX = -log[X]
-For acids/bases: pH = -log[H+]
(ex. if [H+] = 0.012 M, then pH = -log(1.2x10-2) = 1.92)
(ex. if [H+] = 1.2x10-11 M, then pH = -log(1.2x10-11) = 10.92)
Neutral solution pH
-Water at 25C, [H+][OH-]= 1x10-14
-[H+] = 1x10-7 M
-[OH-] = 1x10-7 M
-pH = 7.00
Neutral salt solution
made from reaction of strong base and strong acid (ex. KNO3, KOH is strong base, HNO3 is strong acid)
Basic salt solution
made from reaction of a strong base and a weak acid (ex. Na2S, NaOH is strong base, H2S is weak acid)
Acidic salt solution
made from reaction of a weak base and a strong acid (ex. NH4Br, NH3 is weak base, HBr is strong acid)
Litmus test
-test for acidity or alkalinity using litmus (dye)
-base turns paper blue
-acid turns paper red
-gives qualitative value (yes/no)
Acid-base indicator
-substance that changes color to indicate whether a solution is acidic or basic
-color changes over specific pH ranges
-stable in solution of lower pH: HIn + H2O
-stable in solution of higher pH: H3O+ + In-
monoprotic acid
acid that has one proton to donate (ex. HCl)
(HCl + H2O -> H3O+ + Cl-)
polyprotic acid
acid that has multiple protons to donate (ex. H2SO4)
(H2SO4 + 2H2O -> 2H3O+ + SO4(2-))
The 7 Strong Acids
HCl, HBr, HI, HNO3, H2SO4, HClO3, HClO4
