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Explore the role of acids, bases, and pH in determining the durability of artwork. Discover how different materials and coatings can affect the longevity of outdoor artwork. Watch informative videos and learn about naming acids and bases.
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Chapter 3:Activity 2 Choice of Media for Durability What do you see?
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
H2O Another way to write water is H+(OH)- Water is 1 part acid, 1 part base Water is a neutral compound. pH = 7
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
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
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
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 http://www.youtube.com/watch?v=A_URRb5mk5Q
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 Ammonia It is a base because: NH3 + H2O → + NH4+1(aq) OH-1(aq)
Writing Chemical Formulas for Bases Ex: sodium hydroxide 1. Write the chemical symbol of the metal, then OH NaOH 2. Put up the charges, and criss-cross if necessary. +1 -1 NaOH
Writing Chemical Formulas for Bases Ex: calcium hydroxide 1. Write the chemical symbol f the metal, than OH CaOH 2. Put up the charges, and criss-cross if necessary. +2 -1 Ca(OH)2
Writing Chemical Formulas for Bases Ex: lithium hydroxide 1. Write the chemical symbol f the metal, than OH LiOH 2. 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 elements 2. Ternary acids-H2SO4(aq) -three different elements -polyatomic ions (ending in ate) -polyatomic ions (ending in ite)
Naming Binary Acids EX: HCl(aq) 1. Use the prefix hydrofor hydrogen 2. Anion ending changes from ide to ic 3. Add the word acid at the end. hydrochloric acid
Naming Complex Acids Polyatomic ions ending in ite EX: H2SO3 1. NO hydro prefix!!! 2. Anion ending changes from ITE to OUS -Sulfite change to Sulfurous “RITEOUS” Add the word acid at the end Polyatomic ions ending in ate EX: H2SO4 1. NO hydro prefix!!! 2. Anion ending changes from ATE to IC -Sulfate change to Sulfuric “ICIATEit” 3. Add the word acid at the end
Naming Ternary Acids Polyatomic ions ending in ate EX: H2SO4 1. NO hydro prefix!!! 2. Anion ending changes from ATE toIC -Sulfate change to Sulfuric “ICIATEthat” 3. Add the word acid at the end Sulfuric acid
Naming Ternary Acids Polyatomic ions ending in ite EX: H2SO3 1. NO hydro prefix!!! 2. Anion ending changes from ITE toOUS -Sulfite change to Sulfurous “RITEOUS” • Add the word acid at the end Sulfurous acid
Practice Naming Acids 1. H3PO4(aq) -PO42-= phosphate -Use saying “ICIATEthat” Answer= Phosphoric acid 2. HNO2(aq) -NO21-= nitrite -Use saying “RITEOUS” Answer= Nitrous acid
How to Write a Formula for an Acid: BINARY ACIDS Ex: hydrosulfuric acid 1. 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 charges 4. H2S(aq)
Ternary ACIDS Ex: sulfuric acid 1. No hydro prefix so we have a polyatomic ion: In this case “ICIATEthat” 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 charges 5. H2SO4(aq)