Chapter 3:Activity 2 Choice of Media for
Durability
What do you see?
What are acids and bases?
Acids
• Always contain H+ (ex. HCl, H2SO4)• Acidic foods have a sour taste• Neutralize bases• React with most metals• Turns blue litmus red• Have a pH <7• Turns universal indicator yellow, orange, or red
Bases
• Contain OH- (ex. NaOH, KOH)• Have a bitter taste• Feel slippery• Neutralize acids• Are corrosive• Have a pH >7• Turn red litmus blue• Turn universal indicator green, blue, or purple
Acids vs Bases
Acids vs Bases
pH• Is a measure of how much H+
is in a solution sample.• If H+= OH- then, pH=7 and the
solution is neutral.• If H+ > OH-, then pH<7 and
the solution is acidic.• If OH- >H+, then pH>7 and the
solution is basic.• The pH scale goes from 0-14,
with 7 being neutral
Universal Indicator Scale
Take a look at this!!!!!
How is pH important to artwork?
What has happened here?
How Does This Happen?
SO2(g) + H2O(l) H2SO3(aq)sulfurous acid
SO3(g) + H2O(l) H2SO4(aq) sulfuric acid
NO3(g) + H2O(l) HNO3(aq) nitric acid
Conoco Philips Plant, Linden NJ
Conoco Philips Plant, Linden NJ
What does acid rain do?CaCO3(s) + H2SO4(aq) CaSO4(aq) + H2O(l) + CO2
Marble sulfuric acid calcium sulfate water carbon dioxide
Dissolves in the water and washes
away
Zn (s) + H2SO4(aq) ZnSO4(aq) + H2(g) zinc metal sulfuric acid zinc sulfate hydrogen gas
Zinc is usually a good metal choice for outdoor stuff, but in the presence of acid rain, it reacts and washes away.
In 1992, after being displayed outdoors in an urban-industrial environment for over 60 years, Philadelphia’s version of Rodin’s The Thinker showed the effects of "acid rain" and particulate deposition common in such atmospheres. Streaking, caused by the run-off of condensate from the sculptural forms, had etched a pattern of irregular rivulets in the surface, while urban aerosols from industrial and vehicular sources built up black and other accretions. The forms were obscured; Rodin’s modeling could no longer be "read," with some high points black and recesses bright due to corrosion.
Philadelphia Museum of Art
What might be a better choice of material for outdoor art?
SiO2(s) + H2SO4(aq) no reaction Sandstone and granite sulfuric acid
Other alternatives???
The copper in this piece of artwork wouldn’t stand a chance exposed to air and water, BUT a protective coating over it can keep it looking new for ages!
How would a protective coating have affected this famous piece of
art?
Ted Talk
https://www.youtube.com/watch?v=DupXDD87oHc
Acids Both Bases
Sour taste Bitter taste
pH <7 pH >7
Blue litmus -red Red litmus-blue
Reactive w/metals Not reactive w/metals
H+ ions or H3O+ ions (hydronium)
OH- ions (hydroxide)
Conducts electricity
Corrosive
Naming Bases
A BASE is a substance that when put into water, gives away a hydroxide ion (OH-1) to another substance in the water solution.
NaOH(s) + H2O → Na+1(aq) + OH-1
(aq)
Naming Bases
1. Name the metal first and then the hydroxide ion
Ex: NaOH
Sodium hydroxide
Naming Bases
1. Name the metal first and then the hydroxide ion
Ex: KOH
Potassium hydroxide
Naming Bases
1. Name the metal first and then the hydroxide ion
Ex: Ca(OH)2
Calcium hydroxide
Naming Bases
1. A base that is commonly used is
Ex: NH3 AmmoniaIt is a base because:
NH3 + H2O → + NH4+1
(aq) OH-1(aq)
Writing Chemical Formulas for Bases
Ex: sodium hydroxide1. Write the chemical symbol f the metal, than OH NaOH2. Put up the charges, and criss-cross if necessary.
+1 -1
NaOH
Writing Chemical Formulas for Bases
Ex: calcium hydroxide1. Write the chemical symbol f the metal, than OH CaOH2. Put up the charges, and criss-cross if necessary.
+2 -1
Ca(OH)2
Writing Chemical Formulas for Bases
Ex: lithium hydroxide1. Write the chemical symbol f the metal, than OH LiOH2. Put up the charges, and criss-cross if necessary.
+1 -1
LiOH
Naming Acids
An ACID is a substance that when put into water, gives away a hydrogen ion (H+1) to another substance in the water solution.
HCl + H2O → H+1(aq)
+ Cl-1(aq)
Types of Acids
There are two types of acids:1. Binary acids-HCl(aq)
-two different elements2. Ternary acids-H2SO4(aq)
-three different elements
-polyatomic ions (ending in ate)-polyatomic ions (ending in ite)
Naming Binary AcidsEX: HCl(aq)
1. Use the prefix hydro for hydrogen2. Anion ending changes from ide to ic3. Add the word acid at the end.
hydrochloric acid
Naming Complex AcidsPolyatomic ions ending in ate
EX: H2SO4
1. NO hydro prefix!!!2. Anion ending changes from ATE to IC
-Sulfate change to Sulfuric “IC I ATE it”
3. Add the word acid at the end
Polyatomic ions ending in ite
EX: H2SO3
1. NO hydro prefix!!!2. Anion ending changes from ITE to OUS
-Sulfite change to Sulfurous “RITEOUS”3.Add the word acid at the end
Polyatomic Ion Name of Polyatomic ion
Acid formula Name of acid
Naming Ternary AcidsPolyatomic ions ending in ate
EX: H2SO4
1. NO hydro prefix!!!2. Anion ending changes from ATE to IC
-Sulfate change to Sulfuric “IC I ATE that”
3. Add the word acid at the end
Sulfuric acid
Naming Ternary AcidsPolyatomic ions ending in ite
EX: H2SO3
1. NO hydro prefix!!!2. Anion ending changes from ITE to OUS
-Sulfite change to Sulfurous “RITEOUS”3.Add the word acid at the end
Sulfurous acid
Practice Naming Acids
1. H3PO4(aq)
-PO42-
= phosphate
-Use saying “IC I ATE that”Answer= Phosphoric acid
2. HNO2(aq)
-NO21-
= nitrite
-Use saying “RITEOUS”Answer= Nitrous acid
Writing Chemical Writing Chemical Formulas for AcidsFormulas for Acids
How to Write a Formula for an Acid:BINARY ACIDSEx: hydrosulfuric acid1. Write down symbols (H and S)
2. Determine Charges (H+1 S-2)
3. Cancel charges or use criss-cross method to form subscripts to cancel out charges4. H2S(aq)
Ternary ACIDSEx: sulfuric acid1. No hydro prefix so we have a polyatomic ion: In this case “IC I ATE that”
sulfuric = sulfate (SO4)-2
Can also be “RITEOUS” sulfurous = sulfite 2. Write down symbols (H and SO4)
3. Determine Charges (H+1 SO4 -2)
4. Cancel charges or use criss-cross method to form subscripts to cancel out charges5. H2SO4(aq)