Quiz Combustion, Synthesis Reaction, Decomposition reaction, Single replacement, Double - PowerPoint Presentation

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Quiz

Combustion, Synthesis Reaction, Decomposition reaction, Single replacement, Double replacementIdentify Type: 2H2O2 (l)  2 H2O (l) + O2 (g) Identify Type: SiO2 (l) + 2C (s)  Si (l) + 2CO (g) Does this reaction take place? Al2(SO4)3 + 2 Fe  Fe2(SO4)3 + 2 AlList all spectator ions in the following equation.Ba(NO3)2(aq)+2NaSO4(aq) BaSO4(s)+2 NaNO3(aq)

Quiz

Combustion, Synthesis Reaction, Decomposition reaction, Single replacement, Double replacementIdentify Type: 2H2O2 (l)  2 H2O (l) + O2 (g) Identify Type: SiO2 (l) + 2C (s)  Si (l) + 2CO (g) Does this reaction take place? Fe2(SO4)3 + 2 Al  Al2(SO4)3 + 2 FeList all spectator ions in the following equation.Ba(NO3)2(aq)+2NaSO4(aq) BaSO4(s)+2 NaNO3(aq)

5.3 Redox reaction

What is an

ion? Any charged atoms or moleculesHow do you become ‘charged’?By losing or gaining electronsWhat is a cation? Did it lose or gain electrons?Positive ion, it LOST electronsWhat is an anion? Did it lose or gain electrons?Negative ion, it GAINED electronsThe charge of an ion are also known as oxidation numbers

More Practice

If a metal iron, Fe, becomes an ion, Fe3+, how many electrons did it lose or gain?It lost 3 electronsIf a pure sulfur, S, becomes an ion, S2-, how many electrons did it lose or gain?It gained 2 electrons

Rules to find oxidation numbers

Neutral elements and diatomic molecules have an oxidation number of zero. Ex. Na, Fe, H2, O2, F2Monatomic ions have oxidation number equal to its charge. Ex, Na+ is 1, O2- is -2. Do you know how to use P.T to find oxidation #? Oxidation numbers in polyatomic ions add up to the total charge of the ion. Ex: shown NS

Example

Sulfate is a polyatomic ion, with the formula of SO42-The oxidation number of sulfur and four oxygen must add up to -2Since oxygen is -2, the total negative charge of it is -8 (-2 * 4)Sulfur must have an oxidation number of +6, to balance the oxygen, for the ion to have a charge of -2

(cations first, anions second)

What are the oxidation number of the elements in a nitrate ion?NO3-Oxygen is -2Nitrogen is 5

Redox Reactions

We have covered 5 major types of chemical reactionsRedox reaction is a totally different way to classify reactions, which can encompass all of the 5 major reactionsAs long as reactants and products are exchanging electrons, it is called a redox reaction

CuSO

4(aq) + Zn  Cu + ZnSO4(aq)Copper(II) sulfate (CuSO4)is blue, zinc(II) sulfate (ZnSO4)is clearThis is a redox reaction because copper is exchanging electrons with zinc

Copper sulfate (

CuSO4) dissolves in water to form two ions, copper (II) ion and sulfate ionCu2+ and SO42-How do we know copper is +2?Because we memorized sulfate(SO42-) a charge of -2, and so copper (II) ion needs to be +2 to make CuSO4 neutralA roman numeral in parentheses represents the charge, and are needed for ALL transitional metal ions!

The zinc metal gives the copper (II) ion (Cu

2+) two electronsThe zinc metal now becomes zinc (II) ion (Zn2+) while copper (II) ion (Cu2+) becomes copper metal (Cu) by gaining the two electronsReminder: electrons are negatively charged!

When zinc lost the electrons (gave it away), the reaction, Zn

 Zn2+ + 2e-, is called oxidation reactionWhen copper (II) ion gained the electrons, the reaction, Cu2+ + 2e-  Cu, is called reduction reactionOxidation and reduction reaction happens at the same time, which we call redox reaction

Cu

2+ + 2e-  Cu Copper (II) ion CopperCopper (II) ion was reduced (gained e-)

Zn

 Zn+2 + 2e- Zinc zinc (II) ion Zinc was oxidized (lost e-)

LEO the lion says GER

Loss of Electrons is OxidationGaining Electrons is ReductionOIL RIGmOre positive (Oxi)lEss positive (rEduc)

Aluminium

LOST 3 electrons. Which one is the correct equation? A) Al + 3e-  Al3+ Al  Al3+ + 3e-Is this Oxidation or Reduction?

Identify reduction and oxidation reaction

AgNO3(aq)  + Cu → CuNO3(aq)  + Ag Ag+ NO3- Cu+ NO3- Silver (I) ion Copper (I) ionAg+ gained, so reduction. Less positive.Cu lost, so oxidation. More positive

Identify reduction and oxidation reaction

2 Na + FeCl2 → 2 NaCl + Fe Fe2+ 2Cl- Na+ Cl- iron (II) ion sodium ionReduction: Iron, gained e-, less positiveOxidation: Sodium, lost e-, more positive