6AB A + B ONE PRODUCT!! Synthesis Two or more reactants combine to form…ONE PRODUCT!!ABA + B
7Two reactants form one product Synthesis Continued22Mg O2 MgOTwo reactants form one productBUT WAIT!!Don’t forget about everything you have already learned! Is your equation balanced??
8Predicting productsBefore we keep going… lets learn a few things about predicting products
9Predicting productsHere are a few important things to remember when predicting products:The compounds form must be neutral ionic compounds (which means you’ll be paying attention to their charges)You do NOT carry subscripts from the reactants to the products.You always balance your equation LAST
10Let’s go back to that synthesis example Remember the reaction:Mg O2 Helpful hint for later…why is oxygen O2 and not just O?Click to find out why
11Why O2??Oxygen is a diatomic molecule, which means when oxygen is by itself it must be O2. Remember that this DOES NOT mean that oxygen is O2 in compounds, only by itself!What are the other diatomic elements? (hint: remember the heavenly 7!F2H2Br2N2I2Cl2O2Go back
12Now to predict the products… Mg O2 Remember A + B AB so Mg + O2 will make a compound with magnesium and oxygen. What does a compound with magnesium and oxygen look like??
13A compound with magnesium and oxygen… Magnesium is a metal, oxygen is a nonmetal so we must be forming an IONIC compound.What’s the charge of Mg?What’s the charge of O?O 2-Mg 2+
15Nope!MgO2+2 + 2(-2) DOES NOT EQUAL ZEROTry again!
16Nope!Mg2O22(+2) + 2(-2) = 0 But remember ionic compounds need to be in the simplest formTry again!
17Mg + O2 MgO 2Mg + O2 2MgO Yes! Very good! MgO is a neutral, correct ionic compound so our formula isMg O2 MgOFinally, balance the equation to satisfy the law of conservation of mass…2Mg O2 2MgO
18So remember… When predicting products: Make correct ionic compoundsTHEN balanceLet’s move on to the rest of the reaction types…
20DecompositionONE REACTANT…forms two or more productsA + BAB
21Decomposition Continued The electrolysis of water is when water decomposes into hydrogen and oxygen gas as shown below:2H2O 2H2 + O2
22Predicting products and decomposition Lets use that same reaction. What if we were not already given the products, how would we predict them?H2O ??Water is made of hydrogen and oxygen, so will my products just be H and O?
23But wait….something is still missing…. No!Remember, H and O are both diatomic elements.H2O H2 + O2But wait….something is still missing….
24Balance!Don’t forget to balance your equation after you make your products! Your final answer should look like this:2H2O 2H2 + O2
25You try one…What is the correct reaction for the decomposition of sodium chloride, NaCl?NaCl Na + Cl2NaCl Na2 + Cl22NaCl 2Na + Cl2
26Nope!NaCl Na + ClDon’t forget that chlorine is a diatomic element, so it must be Cl2Try again!
27Nope!2NaCl Na2 + Cl2Although this reaction is correctly balanced, sodium is NOT a diatomic elementTry again!
28Yes! Very good!2NaCl 2Na + Cl2This is a correct reaction for the decomposition of sodium chloride.Ready for the last type of reaction?
30Hydrocarbon?? What’s that?? Click to find out! CombustionCombustion is the burning of hydrocarbons.Hydrocarbon?? What’s that?? Click to find out!When a hydrocarbon reacts with oxygen (O2), the products are ALWAYS…..Yes, ALWAYS…Carbon dioxide and waterCO H2O
31HydrocarbonsA hydrocarbon is an organic molecule made up of hydrogen and carbon. Remember when we learned about these when we talked about organic chemistry??C20H42CH4C6H10
32Balance this equation… Combustion Cont…Since the products of a combustion reaction are always CO2 and H2O, the hardest part about combustion reactions is balancing themCH O2 CO H2OBalance this equation…
33CH4 + O2 CO2 + 2H2O Combustion Cont. 4C3H9 + 21O2 12CO2 + 18H2O Be aware… this reaction was pretty easy to balance, some of the combustion reactions get pretty complicated! Like this one…4C3H9 + 21O2 12CO2 + 18H2O
34Not quite, review the types of reactions with me… Ready for your quiz??Yes!Not quite, review the types of reactions with me…
35Ok, now I’m ready for the quiz! ReviewSynthesis reactions: two or more reactants combine to form ONE productA + B ABDecomposition reactions: ONE reactant breaks down into two or more productsAB A + BCombustion reactions: a hydrocarbon reacts with oxygen to produce carbon dioxide and water.Hydrocarbon + O2 CO2 + H2OOk, now I’m ready for the quiz!
36Quiz Question 1/5 Which of the following is a decomposition reaction? 2Fe + O2 2FeONa + AgCl Ag + NaClNa2S 2Na + S
37Nope!2Fe + O2 2FeOThis is two reactants forming ONE product which is an example of a synthesis reactionTry again!
38Nope!Na + AgCl Ag + NaClThis reaction does not just form one product. This reaction is an example of a single replacement reaction which we will learn about later.Try again!
39Yes! Very good!Na2S 2Na + SThis reaction is ONE reactant breaking down into two or more products, which is an example of a decomposition reaction.Back to the question!Next question!
40Quiz Question 2/5 How can you recognize a combustion reaction? A combustion reaction is the only reaction always has at least two reactants and two products. One of the reactants is always oxygen gas.A combustion reaction always has a hydrocarbon reacting with oxygen to produce carbon dioxide and water.A combustion reaction always has a hydrocarbon reacting with nitrogen, which is a very explosive reaction.
41Nope!A combustion reaction is the only reaction always has at least two reactants and two products. One of the reactants is always oxygen gas.We will learn about other reactions that can have more than one product and more than one reactant. This is NOT the way to identify a combustion reaction.Try again!
42Nope!A combustion reaction always has a hydrocarbon reacting with nitrogen, which is a very explosive reaction.Although combustion reactions are typically explosive, it is not because they react with nitrogen.Try again!
43Yes! Very good! This is how we identify a combustion reaction A combustion reaction always has a hydrocarbon reacting with oxygen to produce carbon dioxide and water.This is how we identify a combustion reactionBack to the question!Next question!