CHAPTER 8 Section 1. Chemical Reaction – the process by which one or more substances are changed...
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Transcript of CHAPTER 8 Section 1. Chemical Reaction – the process by which one or more substances are changed...
CHAPTER 8
Section 1
Chemical Reaction – the process by which one or more substances are changed into one or more different substances
Reactants – the original substancesProducts – the resulting substancesChemical Equation – represents with
symbols and formulas the identity of the substances and the relative amounts of the reactants and products in a chemical reaction.
Indications of a Chemical Reaction
Heat and LightMatch
Gas producedHC2H3O2 and NaHCO3
Formation of a PrecipitatePrecipitate (ppt) – a solid produced in a
chemical reactionNaCl and AgNO3
Color ChangeNaOH and Phenolphthalein
Characteristics of Chemical Equations
The equation must represent known facts
The equation must contain correct formulas for reactants and products
The law of conservation of mass must be satisfiedCoefficient – a small whole number that appears in front
of a formula in a chemical equation
Equations
Word Equation- an equation in which the products and reactants in a chemical reaction are represented by words
Methane + oxygen → carbon dioxide + water
→ - yields, produce, or form
Equations
Formula equation – represents the reactants and products of a chemical reaction by their symbols or formulas
CH4(g) + O2(g) → CO2(g) + H2O(g)
(g) represents state
→ - yields↔ - reversible rxn(s) - solid(g) - gas(l) - liquid(aq) - aqueous (dissolved in water)→ - rxn heated, other specific conditions
examples
Symbols
Δ
Law of Conservation of Mass and Formula Equations
CH4(g) + O2(g) → CO2(g) + H2O(g) not balanced
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) balanced
Practice
CS2(l) + O2(g) → CO2(g) + SO2(g)
NaCl(aq) + AgNO3(aq) →NaNO3(aq) + AgCl(s)
PbCl2(aq)+Na2CrO4(aq) → PbCrO4(s) +NaCl(aq)
Practice
CS2(l) + 3O2(g) → CO2(g) + 2SO2(g)
NaCl(aq) + AgNO3(aq) →NaNO3(aq) + AgCl(s)
PbCl2(aq) + Na2CrO4(aq) → PbCrO4(s) + 2NaCl(aq)
Balancing equations
Write formula equations – make sure you have correct formulas
Balance elements that appear only once on each side
Balance polyatomic ions as single units (in most cases)
Balance H and O last
Examples
Examples
Magnesium and hydrochloric acid react to produce magnesium chloride and hydrogen.
Nitric acid reacts with magnesium hydroxide to produce magnesium nitrate and water
When copper reacts with silver nitrate, the products are copper(II) nitrate and silver
The reaction between iron(III) oxide and carbon monoxide gas produces iron and carbon dioxide.
Practice
Solid calcium reacts with solid sulfur to produce solid calcium sulfide
Hydrogen gas reacts with fluorine gas to produce hydrogen fluoride gas
Solid aluminum metal reacts with aqueous zinc chloride to produce solid zinc metal and aqueous aluminum chloride