Chemical Reactions. Chemical Reactions Chemical reactions have a standard format when written:

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0.3.notebook A chemical property is a behaviour that occurs when substances change to create a new substance.

New colour Evidence of chemical change: Example 1: when baking soda is added to acids like vinegar, carbon dioxide gas bubbles form.

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 reaction that creates rust is a chemical change.

Evidence of change Tesing for the production of certain substances after a reaction: Reactants Products A+ B C + D The reactants are the chemicals that go in to a

unknown substances (ex. testing for different gases).

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"

1 0.3.notebook 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. New colour Evidence of chemical change: Example 1: when baking soda is added to acids like vinegar, carbon dioxide gas bubbles form. Bubbles 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. Chemical Change Chemical reactions have a standard format when written: Precipitate Light (solid formed) Difficult/impossible to reverse Temperature Change Evidence of change Tesing for the production of certain substances after a reaction: 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 Reactants/Products 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 = 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" Word Equation Testing p. 219 # Examine the following word equation: propane + oxygen à 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. p. 219 #2 4 1

2 p. 219 # 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? EQUATIONS A skeleton equation is a chemical reaction represented by formulas of the reactants instead of the chemical names. copper + silver nitrate silver + copper (II) nitrate 3. Write word equations for the following reactions: a) CaCl2 and Na2SO4 react to form CaSO4 and NaCl Cu + AgNO 3 Ag + CuNO 3 b) BaCO3 reacts when heated to produce BaO and CO2 iron + oxygen iron(iii) oxide 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. zinc + hydrogen chloride hydrogen + zinc chloride b) Stalactites form in caves when calcium bicarbonate reacts to form calcium carbonate, water, and carbon dioxide gas. hydrogen + oxygen water vapour p. 219 #2 4 Skeleton Equation 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. CH 4 + 2O 2 2H 2 O + CO 2 EQUATIONS Steps to writing balanced chemical equations: 1. Write the skeleton equation iron + oxygen iron oxide Fe + O 2 Fe 3 O 4 2. Count the # of atoms of each type in reactants & products Atom Reactants Products Fe 1 3 O Multiply each of the formulas by the appropriate coefficients to balance the number of atoms. 3Fe + 2O 2 Fe 3 O 4 Balanced Equation Chemical Equations p. 229 #2,3 2. Copy the following skeleton equations into your notebook, then balance the equations. a) Na + Cl 2 NaCl b) K + O 2 K 2O c) H 2 + O 2 H 2O d) H 2 + Cl 2 HCl e) N 2 + H 2 NH 3 f) CO + O 2 CO 2 g) Al + Br 2 AlBr 3 h) N 2H 4 + O 2 H 2O + N 2 i) CH 4 + O 2 CO 2 + H 2O 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 copper + water b) lead(ii) nitrate + potassium iodide lead(ii) iodide + potassium nitrate c) calcium + water calcium hydroxide + hydrogen gas d) lead(ii) sulfide + oxygen lead + sulfur dioxide e) hydrogen sulfide hydrogen + sulfur Bead Balancing Strategy N 2 H 4 + O 2 H 2 O + N 2 Diagram Strategy p. 229 #2 3 Bead Balancing 2

3 TYPES There are five main types of chemical reactions: Combustion fuel + oxygen oxides + energy TYPES There are five main types of chemical reactions: Combustion the explosive relationship Synthesis A B AB Decomposition + + AB A B Synthesis the hook up Decomposition the break up Single A BC B + + AC Double AB+ CD AC + BD Single the semi switcheroo Double the full switcheroo Types of Reactions Types of Reactions p. 247 #4 & 5 4. Identify each of the following reactions as one of the types of reactions: a) barium + sulfur barium sulfide b) bromine + sodium iodide iodine + sodium bromide c) barium nitrate + sodium sulfide barium sulfide + sodium nitrate d) lithium carbonate carbon dioxide + lithium oxide e) lead(ii) oxide lead + oxygen f) calcium + water hydrogen + calcium hydroxide g) sulfur trioxide + water sulfuric acid 5. Write & balance skeleton equations for each of the reactions above. p. 247 #4 & 5 4. Identify each of the following reactions as one of the types of reactions: a) barium + sulfur barium sulfide b) bromine + sodium iodide iodine + sodium bromide c) barium nitrate + sodium sulfide barium sulfide + sodium nitrate d) lithium carbonate carbon dioxide + lithium oxide e) lead(ii) oxide lead + oxygen f) calcium + water hydrogen + calcium hydroxide g) sulfur trioxide + water sulfuric acid p. 247 #4,5 p. 247 #4,5 p. 247 #4 & 5 5. Write & balance skeleton equations for each of the reactions. a) barium + sulfur barium sulfide b) bromine + sodium iodide iodine + sodium bromide c) barium nitrate + sodium sulfide barium sulfide + sodium nitrate d) lithium carbonate carbon dioxide + lithium oxide 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 e) lead(ii) oxide lead + oxygen f) calcium + water hydrogen + calcium hydroxide Example: methane + oxygen water + carbon dioxide 10 g before reaction 10 g after reaction What would happen if a gas was produced? g) sulfur trioxide + water sulfuric acid #5 Answers Conservation of Mass 3

Formulas of Acids Formulas of Bases p. 295 #3 & 4 p. 295 #3 & 4 p.295 #3&4 p.

hydrogen ion has an ionic charge of 1+ (H + ).

To name acids, follow these simple guidelines: H + ate = ic acid H 2SO 4 = sulfuric acid H + ite = ous

and acid formed when H + combines with polyatomic ions that contain oxygen.

are very hazardous, but diluted acids and bases can be useful.

4 Formulas of Acids Formulas of Bases p. 295 #3 & 4 p. 295 #3 & 4 p.295 #3&4 p.295 #3&4 Ionic Compounds: Acids o o 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. To name acids, follow these simple guidelines: H + ate = ic acid H 2SO 4 = sulfuric acid H + ite = ous acid H 2SO 3 = sulfurous acid H + element = hydro ic acid HCl = hydrochloric acid An oxyacid is simply and acid formed when H + combines with polyatomic ions that contain oxygen. Crash Course Chemistry: Acid Base Reactions 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. Acids ph Scale 4

Acids & Bases: The ph Scale ph Scale ph Scale

Bases: Ionic compounds Contain hydrogen atoms

reactive Good electrical conductors Corrosive &

Dissolve in water & release OH Bitter tasting

Corrosive & dangerous when strong Litmus

5 Acids & Bases: The ph Scale ph Scale ph Scale Acids & Bases: Properties Acids: Ionic compounds Bases: Ionic compounds Contain hydrogen atoms Dissolve in water & release H + Sour tasting Very reactive Good electrical conductors Corrosive & dangerous when strong Contain hydroxide ions Dissolve in water & release OH Bitter tasting React with proteins Good electrical conductors Corrosive & dangerous when strong Litmus Properties of Acids Acids & Bases: Properties Acids & Bases: Properties Acids Bases 5

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.

6 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 > H 2 O + NaBr acid base water salt 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. Acid Base Reactions Acid Base Reactions #3 6

Chemical Reactions and Equations

Chemical Reactions and Equations 5-1 5.1 What is a Chemical Reaction? A chemical reaction is a chemical change. A chemical reaction occurs when one or more substances is converted into one or more new