Experiment 7 Chemical Reactions

Part I Combination reaction

2Mg + O2 2MgOEquation for the burning of Mg ribbonSandpaper removes the tarnish and exposes the shiny/lustrous surface of Mg.The ash is gray in color

Part II Decomposition Reaction CuSO4 5H2O CuSO4 + 5H2O Blue crystal grayish powder

Water vapor is formed at the upper portion of the test tube.

Part III Single Replacement Reaction

KI + Br2 KBr + I2KI is colorless Br2 is reddish brown. The resulting solution is brown.This is single replacement involving halogen. Br displaces I in KI. Br is more reactive than I.

Part IV Double Replacement Reaction

Pb(NO3)2 + K2CrO4 PbCrO4 + KNO3Colorless yellow yellow pptFormation of yellow precipitate

Experiment 8 Oxidation and Reduction

Recall: Oxidation is loss of electron/s; increase in oxidation number Reduction is gain of electron/s; decrease in oxidation numberOxidizing agent substance reducedReducing agent substance oxidized

1. Cu + AgNO3 Cu(NO3)2 + AgRA OA 2. K2Cr2O7 + H2SO4 + H2O2 Cr2(SO4)3 + K2SO4 + O2 + H2O

K2Cr2O7 is OA and H2O2 is RA

3. FeSO4 + H2SO4 + KMnO4 Fe2(SO4)3 + MnSO4 + K2SO4 + H2O FeSO4 is RA and KMnO4 is OATo the product is added KSCN, potassium thiocyanate. If it gives a dark red soln, Fe3+ is present.

2. FeCl3 + KI FeCl2 + KCl + I2 OA RA

FeCl2 + KCl + I2 K3Fe(CN)6 C6H14 Dark blue ppt purpleFe2+ is present I2 is present