Chemical Equations and Reactions Chapter 8 Modern Chemistry

Do Now Each week should be on a new page The # of the week should be at the top of the page Each day of the week should be in the margin

Do Now Week 18 Monday Tuesday Wednesday Thursday Friday

Do Now Complete the following chemical equations. Aluminum + Bromine Sodium + Oxygen Magnesium + Iodine AlBr3 Na2O MgI2

Standards HS-PS1-7: Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction

What are the indications that a chemical reaction has taken place? Essential Question What are the indications that a chemical reaction has taken place?

Vocabulary Chemical Reaction Chemical Equation Precipitate The process by which one ore more substances are changed into one or more different substances Represents, with symbols and formulas, the identities and relative molecular or molar amounts of the reactants and products in a chemical reaction A solid that is produced as a result of a chemical reaction in solution and that separates from the solution.

Chemical Reaction/Equation Use your periodic table to combine two elements to create a chemical reaction. Remember to balance your charges. Be able to explain your reaction.

Precipitate

Indications of a Chemical Reaction Evolution of heat and light together; heat or light is not always a sign of a chemical change. What types of common chemical reactions can you think of that creates both light and heat?

Indication of a Chemical Reaction Production of a gas; usually indicated by the release of gas bubbles. Example carbon dioxide being released when baking soda is mixed with vinegar What types of common chemical reactions can you think of that creates gas bubbles?

Indication of a Chemical Reaction Formation of a precipitate, if a solid appears when two solutions are mixed; this is evidence of a chemical reaction. Silver chromate and Potassium chromate

Color Change Color change; any change of color is usually an indication of a chemical reaction What types of common chemical reactions can you think of that creates a color change?

This is due at the end of the class Practice Write one paragraph to explain the indications of a chemical reaction. Give an example for each indication. This is due at the end of the class

Do Now Write 2-3 sentences to explain the difference between a chemical reaction and a chemical equation?

Characteristics of Chemical Equations A properly written chemical equation must contain: Known facts – Correct element symbols, information from a verified source (periodic table) Correct formulas for the reactants and products (use charges to create the correct formulas. Remember the 7 diatomic molecules The law of conservation of mass must be satisfied – All chemical equations must be balanced. Hydrogen H2 Nitrogen N2 Oxygen O2 Fluorine F2 Chlorine Cl2 Bromine Br2 Iodine I2 Exceptions are S8, and P4

Writing Word and Formula Equations A word equation is an equation in which the reactants and products are represented by words. It has only qualitative meaning, no quantities of reactants or products are given. Provide valuable information needed to write and balance a formula equation. Example methane + oxygen →carbon dioxide and water

Writing Word and Formula Equations A formula equation is an equation in which the reactants and products are represented by symbols and formulas. It has only qualitative meaning, until the equation is balanced are given. Provide valuable information such as the number of moles or atoms of the elements or formulas contained in the equation. Example methane + oxygen →carbon dioxide and water CH4(g) + O2(g) → CO2(g) + H2O(g) Unbalanced CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) balanced

Symbols Used in Chemical Equations List can be found on page 266 of your textbook.

Practice Write word and balanced chemical equations for the following reaction. Include symbols for physical states when indicated. Hydrogen peroxide in an aqueous solution decomposes to produces oxygen and water.

Practice Write word and balanced chemical equations for the following reaction. Include symbols for physical states when indicated. Solid Copper metal reacts with aqueous silver nitrate to produce solid silver metal and aqueous copper nitrate.

Practice Write word and balanced chemical equations for the following reaction. Include symbols for physical states when indicated. Solid zinc metal reacts with aqueous copper sulfate to produce solid copper metal and aqueous zinc sulfate

Explain why all equations need to be balanced. Exit Ticket Explain why all equations need to be balanced.

Do Now Describe a diatomic molecule. List the seven diatomic molecules that appear on the periodic table. What other two elements on the periodic table cannot exist on their own.

Do Now Write the word and formula equation for the chemical reaction that occurs when solid sodium oxide is added to water at room temperature and forms sodium hydroxide(dissolved in water). Try to balance the equation.

Balancing Chemical Equations Essential Question What are the step necessary to balance a chemical equation?

How to Balance an Equation Balance the different types of atoms one at a time First balance the atoms of elements that are combined and that appear only once on each side of the equation. (start with the largest compound first) Balance polyatomic ions that appear on both sides of the equation as single units Balance H atoms and O atoms after atoms of all other elements have been balanced.

Practice Write word and balanced equations for the following. Remember to add symbols for physical states when indicated. Use whiteboards.

Practice 1 Nitrogen dioxide gas reacts with water to form aqueous nitric acid and nitrogen monoxide gas. (the formula for nitric acid is HNO3

Practice 2 Solid potassium chlorate decomposes to form solid potassium chloride and oxygen gas.

Practice Turn to page 274 in your textbooks, complete practice problems 1, a,b, and c

Do Now Write and balance the formula from the word equations below. When chlorine gas reacts with methane(CH4), carbon tetrachloride and hydrogen chloride are produced. When sodium oxide is added to water, sodium hydroxide is produced. 3. In a blast furnace, iron (III) oxide and carbon monoxide gas produce carbon dioxide gas and iron.

Do Now Balance the following equations NaOH →Na2O + H2O Fe + O2 →Fe2O3 CO2 + H2O →C6H12O6 + O2 FeS + HCl →FeCl2 + H2S O2 + H2 →H2O Cl2 + NaI →NaCl + I2 Al(NO3)3 + H2SO4 →Al2(SO4)3 + HNO3

Check Your Answers 2 NaOH →Na2O + H2O 4 Fe + 3O2 →2 Fe2O3 6 CO2 + 6 H2O →C6H12O6 + 6 O2 FeS + 2 HCl →FeCl2 + H2S O2 + 2 H2 →2 H2O Cl2 + 2 NaI →2 NaCl + I2 2 Al(NO3)3 + 3 H2SO4 →Al2(SO4)3 + 6 HNO3

Types of Reactions You need to be able to identify each type. Synthesis reactions Decomposition reactions Single displacement reactions Double displacement reactions Combustion reactions Neutralization reactions You need to be able to identify each type.

1. Synthesis General: A + B → AB Example C + O2 → + A composition reaction produces a single substance from multiple reactants.

Ex. Synthesis Reaction

Practice 2 2 NaCl(s) MgF2(s) 2 AlF3(s) 2 3 Now, balance them. Predict the products. Na(s) + Cl2(g) → Mg(s) + F2(g) → Al(s) + F2(g) → 2 2 NaCl(s) MgF2(s) 2 AlF3(s) 2 3 Now, balance them.

Synthesis Reactions With Oxides Oxides of active metals react with water to produce metal hydroxides. CaO(s) + H2O(l) →Ca(OH)2 (S) What are some other metals that may react with water to produce metal hydroxides? Many oxides of nonmetals react with water to produce oxyacids. SO2(g) + H2O(l)→ H2SO3

2. Decomposition General: AB → A + B Example: NaCl → + A decomposition reactionproduces multiple products from a single reactant

Decomposition Reaction There are many types of decomposition reactions. Decomposition reactions are the opposite of synthesis reactions. Five types of decomposition reactions are:- 1. Decomposition of binary compounds 2. decomposition of Metal Carbonates 3. Decomposition of Metal Hydroxides 4. Decomposition of Metal chlorates 5. Decomposition of Acids

Ex. Decomposition Reaction

Decomposition of Binary Compounds Simplest kind of decomposition reaction Decomposed with heat or electricity (electrolysis) Less active metal oxides decompose with heat Decomposes into its elements

Practice Remember: Compound will be decomposed into its elements HgO ---> H2O ---> MgCl2 ---> FeS --->

Decomposition of Metal Carbonates Decomposes to produce a metal oxide and carbon dioxide gas. Practice CaCO3 ---> Na2CO3 --->

Decomposition of Metal Hydroxides All except for group 1 metals Decompose when heated to yield metal oxides and water. Practice Ca(OH)2 ---> NaOH --->

Decomposition of Metal Chlorates When heated, metal chlorates decompose to form a metal chloride and oxygen. Practice KClO3 ---> Ba(ClO3)2 --->

Decomposition of Acids Some acids decompose into nonmetal oxides and water. Practice H2CO3 → H2SO4→

More Practice 1.ZnCO3 →__________ 2. Ba(ClO3)2 →_______ 3. Sb2O5→___________ 4. CaCO3→__________ 5. KClO3→___________ 6. H2CO3 →__________ 7. Ba(OH)2 →________ 8. HgO →___________ 9. NaCl →___________ 10. H2SO4→_________

Describe a decomposition reaction Exit ticket Describe a decomposition reaction

3. Single Displacement General: AB + C → AC + B Example: Zn + CuCl2 →

Single Displacement Also known as replacement reactions One element replaces a similar element in a compound Commonly occurring in aqueous solutions

Practice l. Ag + KNO3 -----> 2. Zn + AgNO3 ----->

Practice 3. Al + H2SO4 -----> 4. Cl2 + KI -----> 5. Li + H2O ----->

More Practice 5. Li + H2O -----> 6. Cu + FeSO4 -----> 7. Na + H2O -----> 8. Fe + Pb(NO3)2 -----> 9. Cu + H2O -----> 10. Cu + Al2(SO4)3 ----->

Single Displacement/Rule Exceptions Displacement of hydrogen in water by a metal Produces metal hydroxides and hydrogen Ex. Na(s) + H2O(l) → 2 Na(s) + H2O(l) → NaOH(aq) + H2(g) 2 2

Single Displacement/ Rule Exceptions Displacement of Halogens Displacement depends on the position of the halogen in the group Each element can replace any element below it, but not any element above it. Cl2(g) + 2KBr(aq) → 2KCl(aq) + Br2(l) Br2(l) + KCl(aq) → no reaction

Exit Ticket In a single replacement reaction, one ___________________ replaces a _______________ element in a compound. Cl2 + NaI-----→

Ex. Single Replacement Reaction

Single Replacement Reactions Write and balance the following single replacement reaction equation: Zn(s) + HCl(aq) → ZnCl2 + H2(g) 2 NaCl(s) + F2(g) → NaF(s) + Cl2(g) Al(s)+ Cu(NO3)2(aq)→ 2 2 2 3 3 Cu(s)+ Al(NO3)3(aq) 2

4. Double displacement General: AB + CD → AD + CB Example: MgO + CaS →

Double Displacement Ions of two compounds exchange places in an aqueous solution to form two new compounds. Compounds formed are usually precipitates, gas or molecular compounds

Double Replacement Reactions Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together Example: AgNO3(aq) + NaCl(s) → AgCl(s) + NaNO3(aq) Another example: K2SO4(aq) + Ba(NO3)2(aq) → KNO3(aq) + BaSO4(s) 2

Practice Predict the products. HCl(aq) + AgNO3(aq) → CaCl2(aq) + Na3PO4(aq) → Pb(NO3)2(aq) + BaCl2(aq) → FeCl3(aq) + NaOH(aq) → H2SO4(aq) + NaOH(aq) → KOH(aq) + CuSO4(aq) →

5. Combustion Reactions Combustion reactions - a hydrocarbon reacts with oxygen gas to release large amounts of energy in the form of heat and light This is also called burning!!!

Combustion Reactions In general: CxHy + O2 → CO2 + H2O Products are ALWAYS carbon dioxide and water. (although incomplete burning does cause some by-products like carbon monoxide) Combustion is used to heat homes and run automobiles (octane, as in gasoline, is C8H18)

Combustion Example C5H12 + O2 → CO2 + H2O Write the products and balance the following combustion reaction: C10H22 + O2 → 8 5 6

Practice 1. methane (CH4) + oxygen 2. ethane (C2H6) + oxygen 3. propane (C3H8) + oxygen 4. butane (C4H10) + oxygen 5. pentane (C5H12) + oxygen 6. hexane (C6H14) + oxygen 7. ethene (C2H4) + oxygen 8. ethyne (C2H2) + oxygen

Mixed Practice State the type & predict the products. BaCl2 + H2SO4 → C6H12 + O2 → Zn + CuSO4 → Cs + Br2 → FeCO3 →

List and describe the five types of chemical reactions. Exit Ticket List and describe the five types of chemical reactions.