10 2 Classifying Chemical Reactions Synthesis Combustion Decomposition

10. 2 Classifying Chemical Reactions • Synthesis • Combustion • Decomposition • Single Replacement • Double Replacement

Synthesis Reactions “The Dating Game” • Two or more substances react to form one product Word Equation: – A + B AB Lithium metal and chlorine gas react to form solid lithium chloride Skeleton Equation: Li(s) + Cl 2(g) Li. Cl(s) Balanced Equation 2 Li(s) + Cl 2(g) 2 Li. Cl(s)

Synthesis Demo!!! • Magnesium metal reacts with oxygen gas and when heated produces solid magnesium oxide. • Equation:

Combustion Reactions “where there’s smoke there’s fire” • An element or a compound reacts with oxygen, producing energy in the form of heat and light. – i. e. H 2(g) + O 2(g) H 2 O(g) – This looks like a synthesis reaction! • When the reactant is a hydrocarbon (contains H and C), the product will be carbon dioxide gas, water vapor, and energy

Word Equation: Propane gas (C 3 H 8) in a grill reacts with oxygen gas to yield carbon dioxide gas, water vapor and heat energy Skeleton Equation: C 3 H 8(g) + O 2(g) CO 2(g) + H 2 O(g) + energy Balanced Equation: C 3 H 8(g) + 5 O 2(g) 3 CO 2(g) + 4 H 2 O(g) + energy

Combustion Demo!!! • Methane gas (CH 4) burns in a bunsen burner. • Equation:

Decomposition Reactions “The Big Break-up” • One substance decomposes to form two or more products – AB A + B Word Equation: Solid copper(I) carbonate when heated forms solid copper(I) oxide and carbon dioxide gas Skeleton Equation: Cu 2 CO 3(s) Cu 2 O(s) + CO 2(g) Balanced Equation: Cu 2 CO 3(s) Cu 2 O(s) + CO 2(g)

Decomposition Demo!!! • Baking soda (sodium bicarbonate) decomposes upon heating in to solid sodium carbonate, carbon dioxide gas and water vapor. • Equation:

Single Replacement Reactions “The Bully Reaction” • Atoms of one element replace the atoms of a second element in a compound (A + BC BA or AC). • For example, a metal replaces a metal and a nonmetal replaces a nonmetal…like replaces like!

Word Equation: Aqueous copper(I) sulfate reacts with iron metal to form copper metal and aqueous iron(II) sulfate Skeleton Equation: Cu 2 SO 4(aq) + Fe(s) Cu(s) + Fe. SO 4(aq) Balanced Equation Cu 2 SO 4(aq) + Fe(s) 2 Cu(s) + Fe. SO 4(aq)

Predicting Products • When given 2 reactants, you should be able to predict the products. – Determine if the lone element is a metal or a nonmetal. – Determine the metal or nonmetal it will replace in the compound. – Check your activity series. – Replace the metal/nonmetal in the compound with the lone metal/nonmetal. • Make sure to criss cross for the new compound

Activity Series • An activity series helps you to decide if a single replacement reaction will occur • When looking at the activity series, the elements that are listed first can replace the elements listed after them • So, a reaction will happen if the element to be replaced is lower than the element doing the replacing!

Activity Series of Metals Decreasing Activity Name Lithium Potassium Calcium Sodium Magnesium Aluminum Zinc Iron Lead Hydrogen Copper Mercury Silver Symbol Li K Ca Na Mg Al Zn Fe Pb H Cu Hg Ag

Decreasing Activity of the halogens Name Symbol Fluorine Chlorine Bromine Iodine F 2 Cl 2 Br 2 I 2

So, Li can replace K, Ca, Na, etc. i. e. Li + Na. Cl Li. Cl + Na This reaction will occur because Li is higher on the activity series then Na so it can replace Na In the following reaction, no product will be formed. Zn + Mg. O no reaction This reaction won’t occur because Zn is lower on the activity series then Mg so it’s activity isn’t high enough to replace Zn

Predict whether the following reactions will occur. If the reaction WILL occur, tell me the products and balance the equation. 1. Br 2 + Na. I Br 2 + 2 Na. I 2 Na. Br + I 2 2. Cu(s) + Fe. SO 4 no reaction Cu is lower on the activity series then Fe so no reaction will occur

Single Replacement Demo!!! • Baking soda (sodium bicarbonate) decomposes upon heating in to solid sodium carbonate, carbon dioxide gas and water vapor. • Equation:

Double Replacement Reactions “Square Dance” • Two compounds react to yield two different compounds (AB + CD AD + CB). • The metals and nonmetals of the two different compounds switch places. • One of the products must be a solid precipitate, water, or a gas always!!!!!

Word Equation: Lithium phosphate reacts with zinc nitrate to form lithium nitrate and zinc phosphate. Skeleton Equation: Li 3 PO 4 + Zn(NO 3)2 Li. NO 3 + Zn 3(PO 4)2 Balanced Equation 2 Li 3 PO 4 + 3 Zn(NO 3)2 6 Li. NO 3 + Zn 3(PO 4)2

Predicting Products • When given 2 reactants, you should be able to predict the products. – Split each compound in to it’s cations and anions. – Make new compounds using cations and anions from the different compounds • Make sure to criss cross for the new compounds – Determine the state of the new compounds

How do you predict the state of the product? ? • Use the solubility rules to find the state of the products made in either a single or double replacement reaction. • Always start by looking at the anion/negative ion the cation/positive ion – Soluble=aqueous – Not soluble=solid

So, according to our example seen previously, let’s try to predict the state of the reactants and products. . . Balanced Equation 2 Li 3 PO 4 + 3 Zn(NO 3)2 6 Li. NO 3 + Zn 3(PO 4)2 Balanced Equation with states 2 Li 3 PO 4(aq) + 3 Zn(NO 3)2(aq) 6 Li. NO 3(aq) + Zn 3(PO 4)2(s/ppt)

Double Replacement Demo!!! • Aqueous lead(II) nitrate reacts with aqueous potassium iodide. • Equation: