PREDICTING PRODUCTS Chemical Reactions Combustion Reactions Combustion reactions
PREDICTING PRODUCTS Chemical Reactions
Combustion Reactions • Combustion reactions always have SIMILAR reactants: • Cn Hn + O 2 • Cn Hn O + O 2 • Combustion reactions always create the SAME products: • CO 2 + H 2 O • Balance! • C 3 H 8 + O 2 CO 2 + H 2 O • CH 3 CH 2 OH + O 2 CO + H O 2 2
Single Replacement • A + BX AX + B • SINGLE element replaces one of the elements in COMPOUND • NEVER carry a SUBSCRIPT, only the CHARGE of the ion! • Use your polyatomic ion charges and the periodic table/ periodic table of ions • HNO 3 + Zn ? ? ?
Single Replacement • First – give the single element it’s IONIC CHARGE. • Zinc is the SINGLE element and will form a +2 cation. • Second, determine which ELEMENT in the compound the single element will replace. • CATIONS can only replace CATIONS. (positive replaces positive ions) • In this reaction, the hydrogen acts as the cation. Zinc should replace hydrogen. • Next, check the activity series to determine if the reaction will occur.
Activity Series • Activity series - a list of ELEMENTS based on REACTIVITY. • An element in the activity series can replace any element BELOW it. • Only used for single replacement reactions • Since zinc is replacing hydrogen, zinc must be ABOVE hydrogen in the activity series for the reaction to occur. • It is, so the reaction occurs.
Single Replacement • Form PRODUCTS with correct subscripts • BALANCE equation • 2 HNO 3 + Zn H 2 + Zn(NO 3)2 +1 -1 +2 +1 +2 -1
Double Replacement • AX + BY AY + BX • Two COMPOUNDS and the partners will switch! • Again…No subscript, only charge! • Ag. NO 3 + Na. Cl ? ? ?
Double Replacement • Assign CHARGES to each of the IONS. • POSITIVE replaces POSITIVE (or negative replaces negative) • Compounds MUST have a CATION and an ANION • Form PRODUCTS and give them the correct SUBSCRIPTS • Balance the equation. • Ag. NO 3 + Na. Cl ? ? ? +1 -1
Double Replacement • Ag+1 and Na+1 will switch. Na+1 will compound with NO 3 -1 and Ag+1 will compound with Cl-1 • Ag. NO Ag. Cl +1 -1 -1 + Na. NO +1 -13 3 + Na. Cl +1 +1 -1
Synthesis • A + X AX • Two simple ELEMENTS combine to form one compound. • Again…No subscript, only charge! • Na + Cl 2 ? ? ?
Synthesis • Assign CHARGES to each of the ions (if you have a metal and a nonmetal) to create an ionic compound. • Form the PRODUCT and give it the correct subscripts. • Balance the equation. • 2 Na + Cl 2 2 Na. Cl +1 -1
Predicting Products Activity • Match the Reactants with the Products • Take a sheet of paper with you • Your name on paper • Write each equation out • 4 in group – 2 per group member • 3 in group – 3 per group member • Balance the equation • List the reaction • Combustion, Decomposition, Single Replacement, Double Replacement, Synthesis • Staple group together and turn in when finished
Decomposition • AX A + X • Compound breaks apart into two smaller elements/compounds • Acids decompose into water and an oxide. • H 2 CO 3 H 2 O + CO 2 • Metallic hydroxides (anything with a metal and an OH) decompose to form a metallic oxide (metal and oxygen) and water. • Mg(OH)2 Mg. O + H 2 O • Metallic carbonates decompose to form a metallic oxide and carbon dioxide. • Li 2 CO 3 Li 2 O + CO 2
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