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0.3 Chemical Reactions.notebook 1 November 26, 2016 Chemical Change Chemical Reactions A chemical property is a behaviour that occurs when substances change to create a new substance. When a new substance is created, a chemical change has occurred. Example 1: when baking soda is added to acids like vinegar, carbon dioxide gas bubbles form. The fact that baking soda reacts with acid is a chemical property of baking soda. The reaction itself that creates carbon dioxide is a chemical change. Example 2: when an iron nail is left out in the rain, the iron combines with oxygen in the air, causing it to rust. The rust is a new substance called iron (III) oxide. The fact that iron reacts with oxygen a chemical property of iron. The reaction that creates rust is a chemical change. Evidence of change Chemical Reactions • Evidence of chemical change: New colour Temperature Change Bubbles Precipitate (solid formed) Difficult/impossible to reverse Light Reactants/Products Chemical Reactions • Chemical reactions have a standard format when written: Reactants Products A + B C + D • The reactants are the chemicals that go in to a reaction • The products are the chemicals that come out of a reaction • Chemical reactions can be used to make new substances and are also useful for identifying unknown substances (ex. testing for different gases). Acid + Limestone = CO2 gas Testing Chemical Reactions Tesing for the production of certain substances after a reaction: Word Equation Chemical Reactions ‐ EQUATIONS • A word equation is a chemical reaction represented by the names of the substances involved; it indicates what reacts and what is produced. copper + silver nitrate silver + copper (II) nitrate o Left side = reactants; Right side = products o An arrow points from the reactants toward the products o Each reactant and each product is separated by a plus (+) sign The equation read aloud: "copper and silver nitrate react to form silver and copper (II) nitrate" p. 219 #24 p. 219 #2‐4 2. Examine the following word equation: propane + oxygen carbon dioxide + water a) List all the reactants in this reaction b) List all the products in this reaction c) What is the purpose of the arrow in the word equation? 3. Write word equations for the following reactions: a) CaCl2 and Na2SO4 react to form CaSO4 and NaCl b) BaCO3 reacts when heated to produce BaO and CO2 c) AgNO3 reacts with KCl to produce AgCl and KNO3 4. Write word equations to represent the following chemical reactions: a) Carbon dioxide and water are produced in human cell respiration. The reactants are sugar (C6H12O6) and an important gas humans need. b) Stalactites form in caves when calcium bicarbonate reacts to form calcium carbonate, water, and carbon dioxide gas.
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0.3 Chemical Reactions.notebook
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November 26, 2016
Chemical Change
Chemical ReactionsA chemical property is a behaviour that occurs when substances change to create a new substance. When a new substance is created, a chemical change has occurred.
Example 1: when baking soda is added to acids like vinegar, carbon dioxide gas bubbles form.The fact that baking soda reacts with acid is a chemical property of baking soda. The reaction itself that creates carbon dioxide is a chemical change.
Example 2: when an iron nail is left out in the rain, the iron combines with oxygen in the air, causing it to rust. The rust is a new substance called iron (III) oxide. The fact that iron reacts with oxygen a chemical property of iron. The reaction that creates rust is a chemical change.
Evidence of change
Chemical Reactions• Evidence of chemical change: New colour
TemperatureChange
Bubbles
Precipitate(solid formed)
Difficult/impossible to reverse
Light
Reactants/Products
Chemical Reactions• Chemical reactions have a standard format when written:
Reactants Products
A + B C + D• The reactants are the chemicals that go in to a reaction• The products are the chemicals that come out of a reaction
• Chemical reactions can be used to make new substances and are also useful for identifying unknown substances (ex. testing for different gases).
Acid +
Limestone =
CO2 gas
Testing
Chemical ReactionsTesing for the production of certain substances after a reaction:
Word Equation
Chemical Reactions ‐ EQUATIONS• A word equation is a chemical reaction represented by the names of the substances involved; it indicates what reacts and what is produced.
copper + silver nitrate à silver + copper (II) nitrate
o Left side = reactants; Right side = productso An arrow points from the reactants toward the productso Each reactant and each product is separated by a plus (+) sign
The equation read aloud:
"copper and silver nitrate react to form silver and copper (II) nitrate"
p. 219 #24
p. 219 #2‐42. Examine the following word equation:propane + oxygen à carbon dioxide + water
a) List all the reactants in this reactionb) List all the products in this reactionc) What is the purpose of the arrow in the word equation?
3. Write word equations for the following reactions:a) CaCl2 and Na2SO4 react to form CaSO4 and NaClb) BaCO3 reacts when heated to produce BaO and CO2
c) AgNO3 reacts with KCl to produce AgCl and KNO3
4. Write word equations to represent the following chemical reactions:a) Carbon dioxide and water are produced in human cell respiration. The reactants are sugar (C6H12O6) and an important gas humans need. b) Stalactites form in caves when calcium bicarbonate reacts to form calcium carbonate, water, and carbon dioxide gas.
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p. 219 #24
p. 219 #2‐42. Examine the following word equation:
propane + oxygen à carbon dioxide + watera) List all the reactants in this reaction
b) List all the products in this reaction
c) What is the purpose of the arrow in the word equation?
3. Write word equations for the following reactions:a) CaCl2 and Na2SO4 react to form CaSO4 and NaCl
b) BaCO3 reacts when heated to produce BaO and CO2
c) AgNO3 reacts with KCl to produce AgCl and KNO3
4. Write word equations to represent the following chemical reactions:a) Carbon dioxide and water are produced in human cell respiration. The reactants are sugar and an important gas that humans need to survive.
b) Stalactites form in caves when calcium bicarbonate reacts to form calcium carbonate, water, and carbon dioxide gas.
Skeleton Equation
Chemical Reactions ‐ EQUATIONS• A skeleton equation is a chemical reaction represented by formulas of the reactants instead of the chemical names.
copper + silver nitrate à silver + copper (II) nitrate
Cu + AgNO3 à Ag + CuNO3
iron + oxygen à iron(III) oxide
zinc + hydrogen chloride à hydrogen + zinc chloride
hydrogen + oxygen à water vapour
Balanced Equation
Chemical Reactions ‐ EQUATIONS• A balanced chemical equation is a skeleton equation with coefficients in front of certain reactants and/or products to ensure that there are an equal number of atoms of each type on each side of the arrow.
CH4 + 2O2 à 2H2O + CO2
Chemical Equations
Chemical Reactions ‐ EQUATIONS• Steps to writing balanced chemical equations:
iron + oxygen à iron oxide
1. Write the skeleton equation
Fe + O2 à Fe3O4
2. Count the # of atoms of each type in reactants & products
Atom Reactants ProductsFe 1 3O 2 4
3. Multiply each of the formulas by the appropriate coefficients to balance the number of atoms.
3Fe + 2O2 à Fe3O4
p. 229 #23
p. 229 #2,32. Copy the following skeleton equations into your notebook, then balance the equations.a) Na + Cl2 à NaCl b) K + O2 à K2Oc) H2 + O2 à H2O d) H2 + Cl2 à HCle) N2 + H2 à NH3 f) CO + O2 à CO2
g) Al + Br2 à AlBr3 h) N2H4 + O2 à H2O + N2
i) CH4 + O2 à CO2 + H2O
3. For each of the following, write the correct skeleton equation, and then balance it to form a chemical equation:a) copper(II) oxide + hydrogen à copper + waterb) lead(II) nitrate + potassium iodide lead(II) iodide + potassium nitratec) calcium + water à calcium hydroxide + hydrogen gasd) lead(II) sulfide + oxygen à lead + sulfur dioxidee) hydrogen sulfide à hydrogen + sulfur
Bead Balancing
N2H4 + O2 à H2O + N2
Bead Balancing Strategy
Diagram Strategy
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Types of Reactions
Chemical Reactions ‐ TYPES• There are five main types of chemical reactions:
CDAB AC BD
Double Displacement
+ +BC ACA B
Single Displacement
+ +
AAB BDecomposition
A B ABSynthesis
Combustionfuel + oxygen oxides + energy
+ +
Types of Reactions
Chemical Reactions ‐ TYPES• There are five main types of chemical reactions:
Double Displacement
Single Displacement
DecompositionSynthesis
Combustionthe explosive relationship
the hook‐up the break‐up
the semi‐switcheroo the full switcheroo
p. 247 #4,5
p. 247 #4 & 54. Identify each of the following reactions as one of the types of reactions:a) barium + sulfur à barium sulfideb) bromine + sodium iodide à iodine + sodium bromidec) barium nitrate + sodium sulfide à barium sulfide + sodium nitrated) lithium carbonate à carbon dioxide + lithium oxidee) lead(II) oxide à lead + oxygenf) calcium + water à hydrogen + calcium hydroxideg) sulfur trioxide + water à sulfuric acid
5. Write & balance skeleton equations for each of the reactions above.
p. 247 #4,5
p. 247 #4 & 54. Identify each of the following reactions as one of the types of reactions:a) barium + sulfur à barium sulfide
b) bromine + sodium iodide à iodine + sodium bromide
c) barium nitrate + sodium sulfide à barium sulfide + sodium nitrate
d) lithium carbonate à carbon dioxide + lithium oxide
e) lead(II) oxide à lead + oxygen
f) calcium + water à hydrogen + calcium hydroxide
g) sulfur trioxide + water à sulfuric acid
#5 Answers
p. 247 #4 & 55. Write & balance skeleton equations for each of the reactions.
a) barium + sulfur à barium sulfide
b) bromine + sodium iodide à iodine + sodium bromide
c) barium nitrate + sodium sulfide à barium sulfide + sodium nitrate
d) lithium carbonate à carbon dioxide + lithium oxide
e) lead(II) oxide à lead + oxygen
f) calcium + water à hydrogen + calcium hydroxide
g) sulfur trioxide + water à sulfuric acid
Conservation of Mass
Chemical Reactions• The Law of Conservation of Mass states that, in a chemical reaction, the total mass of the reactants (starting materials) is always equal to the total mass of the products (the materials produced).• Mass is determined by the number of atoms in an reaction• This is why we have to balance chemical equations
MASS OF REACTANTS = MASS OF PRODUCTS
Example: methane + oxygen water + carbon dioxide 10 g before reaction 10 g after reactionWhat would happen if a gas was produced?
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Formulas of Acids Formulas of Bases
p.295 #3&4
p. 295 #3 & 4
p.295 #3&4
p. 295 #3 & 4
Acids
o Acids form when hydrogen atoms combine with certain ions§ The hydrogen ion has an ionic charge of 1+ (H+).§ Acids have the subscript aq (aqueous) after their formula.
o To name acids, follow these simple guidelines:
H + ______ate = ____ic acid H2SO4 = sulfuric acidH + ______ite = ____ous acid H2SO3 = sulfurous acidH + element = hydro____ic acid HCl = hydrochloric acid
o An oxyacid is simply and acid formed when H+ combines with polyatomic ions that contain oxygen.
Ionic Compounds: Acids
Crash Course Chemistry: AcidBase Reactions
pH Scale
Acids & Bases: The pH Scale
Concentrated acids and bases are very hazardous, but diluted acids and bases can be useful. Your stomach has hydrochloric acid in it, and baking soda is safe enough to eat.
Chemists use the pH scale (1‐14) to show how strong an acid or base is. Low numbers represent strong acids, and high numbers represent strong bases. Neutral substances like water are in the middle.
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pH Scale
Acids & Bases: The pH Scale
pH Scale
Litmus Properties of Acids
Acids & Bases: PropertiesAcids:Ionic compounds
Contain hydrogen atoms
Dissolve in water & release H+
Sour‐tasting
Very reactive
Good electrical conductors
Corrosive & dangerous when strong
Bases:Ionic compounds
Contain hydroxide ions
Dissolve in water & release OH‐
Bitter‐tasting
React with proteins
Good electrical conductors
Corrosive & dangerous when strong
Acids
Acids & Bases: Properties
Bases
Acids & Bases: Properties
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AcidBase Reactions
A neutralization reaction happens when acids and bases are mixed together.
The products of this kind of reaction are water and a salt. A salt is a special ionic compound made through neutralization. The products are neutral (not acidic or basic).
If there is the right amount and strength of acid and base, the entire solution will be neutral.
Ex: HBr + NaOH ‐> H2O + NaBracid base water salt
AcidBase Reactions
Neutralization reactions are a special case of double displacement. They create specific products that are neutral on the pH scale.
hydrochloric acid reacts with sodium hydroxide to produce water and sodium chloride.
sulfuric acid reacts with potassium hydroxide to produce water and potassium sulfate.
In all neutralization reactions, the hydrogen ion from the acid (H+) joins with the hydroxide ion from the base (OH‐) to form water.
#3
