Chemical Resources and Reactions Applied Chemistry Milbank High School
Chemical Resources What is a chemical resource? • Natural Resource • Renewable Resource • What are some renewable resources?
Chemical Resources • Nonrenewable Resource • What are some nonrenewable resources? • Waste • What are common waste products? • Recycling • How do we recycle?
Household Hazardous Wastes • Cleaning Products • Indoor pesticides • Automotive Products • Painting Supplies • Lawn Products • Misc.
Household Hazardous Wastes • Americans generate 1.6 million tons of HHW per year. • The average home can accumulate as much as 100 pounds of HHW in the basement and garage and in storage closets.
Properties • Words that describe matter (adjectives) • Physical Properties- a property that can be observed and measured without changing the composition. • Examples- color, hardness, m.p., b.p. • Chemical Properties- a property that can only be observed by changing the composition of the material.
Changes • Physical changes- A change that changes appearances, without changing the composition. • Ex. Boil, melt, cut, bend, split, crack • Boiled water is still water. • Chemical changes - a change where a new form of matter is formed. • Ex. Rust, burn, decompose, ferment
Corrosion/Rust • Corrosion • Deterioration of the properties of a material due to reactions with the environment • Reaction with water or air • Rust • Corrosives • Solid, liquid, or gas capable of harming living tissues or damaging material on contact • Not repairable • Acids • Bases
Other Types of Corrosion • Microbial Corrosion • Bacteria • High-temperature corrosion • Aerospace • Power generation
Surface Treatments • Applied coatings • Plating, painting, enamels • Reactive coatings • Corrosion inhibitors • Salts
Economic Impact • A study showed that for 1998 the total annual estimated direct cost of corrosion in the U.S. was approximately $276 billion (approximately 3.1% of the US gross domestic product) • Structures, machines, and containers
Law of Conservation of Mass • Mass can not be created or destroyed in ordinary (not nuclear) chemical reactions or physical change • All the mass can be accounted for. • Burning of wood results in products that appear to have less mass as ash; where is the rest?
All chemical reactions • Have two parts: • Reactants - the substances you start with • Products- the substances you end up with • The reactants turn into the products. • Reactants ® Products
In a chemical reaction • The way atoms are joined is changed • Atoms aren’t created of destroyed. • Can be described several ways: 1. In a sentence Copper reacts with chlorine to form copper (II) chloride. 2. In a word equation Copper + chlorine ® copper (II) chloride
Symbols in equations • the arrow separates the reactants from the products • Read “reacts to form” • The plus sign = “and” • (s) after the formula = solid • (g) after the formula = gas • (l) after the formula = liquid
What is a catalyst? • A substance that speeds up a reaction, without being changed or used up by the reaction. • Enzymes are biological or protein catalysts.
Indications of a chemical reaction: • Energy absorbed or released (temperature changes hotter or colder) • Color change • Gas production (bubbling, fizzing, or odor change) • formation of aprecipitate- a solid that separates from solution (won’t dissolve) • Irreversibility- not easily reversed
Balanced Equation • Atoms can’t be created or destroyed • All the atoms we start with we must end up with • A balanced equation has the same number of each element on both sides of the equation.
® O + C C O O O • C + O2® CO2 • This equation is already balanced • What if it isn’t?
® O + C C O O • C + O2® CO • We need one more oxygen in the products. • Can’t change the formula, because it describes what it is (carbon monoxide in this example)
C O ® O + C O • Must be used to make another CO • But where did the other C come from? C O
C C O ® O + O • Must have started with two C • 2 C + O2® 2 CO C O C
Rules for balancing: • Assemble, write the correct formulas for all the reactants and products • Count the number of atoms of each type appearing on both sides • Balance the elements one at a time by adding coefficients (the numbers in front) - save H and O until LAST! • Check to make sure it is balanced.
Never • Never change a subscript to balance an equation. • If you change the formula you are describing a different reaction. • H2O is a different compound than H2O2 • Never put a coefficient in the middle of a formula • 2 NaCl is okay, Na2Cl is not.
Balancing Examples • _AgNO3 + _Cu ® _Cu(NO3)2 + _Ag • _Mg + _N2® _Mg3N2 • _P + _O2® _P4O10 • _Na + _H2O ® _H2 + _NaOH • _CH4 + _O2® _CO2 + _H2O