In other words, atoms are not created nor destroyed in chemical reaction.

Transcription

1 CUNTING Physcisal Methds Chemical Methds by numbers 1 pr = 2 1 dz = 12 1 case = 12 r 24 1 hand = 5 fingers 1 ft = 12 inches Avgadr's number = 6.02x anything anything by weighing 1 gummy bear = 1 gram 1 penny = 1 gram 1 prtn = 1 amu 1 neutrn = 1 amu 1 hydrgen-1 atm = 1 amu 1 carbn-12 atm = 12 amu numbers t amunts by weighing by vlume any gas = C,1atm carbn-12 = 12 grams carbn-12 exactly (6.02x ) (6.02x ) the eletrlysis f 36 grams f water will prduce mlar masses defined by balanced reactin 2 mlecule 2 mlecules cule multiply thrugh by A number 2 x A number 2 x A number 1 x A number A number equals Avgadr's # 2 x 6.02x x 6.02x x 6.02x Avgadr's # equals 2 x 2 x 1 x cunt by weighing 2 x 18 grams 2 x 2 grams 1 x 32 grams H 2 H 2 H2 H 2 4 grams f hydrgen and 32 grams xygen Chemical Methds by balanced reactin This is a chemical recipe fr the decmpsitin f water by electrlysis. 2 mlecule 2 mlecules cule multiply thrugh by A number 2 x A number 2 x A prducts number 1 x A number A number equals Avgadr's # 2 x 6.02x x 6.02x x 6.02x Avgadr's # equals 2 x 2 x 1 x reactants What did Jhn Daltn in 1808 have t say abut chemical reactins? Is this Chemical Atms true are fr reactins cnserved the decmpsitin invlve a chemical just f the water reactin. simple by rearrangement electrlysis? f atms. In ther wrds, atms are nt created nr destryed in chemical reactin. cunt by weighing x 18 grams 2 x 2 grams 1 x 32 grams 2 H 2 2 H 2 H H2 H 2 1

2 1. Chemical reactins invlve just the simple rearrangement f atms. 2. Atms are cnserved in a chemical reactin. In ther wrds, Let s atms see are if Jhn nt created Daltn had nr destryed assumed crrectly. in chemical reactin. This ture fr the abve decmpsitin f water by electrlysis. 4 hydrgen atms 4 hydrgen atms 2 xygen atms 2 xygen atms Cmbinatin - Synthesis (the REDX prcess defined) 1 Fe + 1Cl 2 (g) 1 FeCl 2 Analyzing the half reactins Fe plus chlrine gas frms> irn (II) chlride Fe 2+ Cl Cl Fe e - xidatin IL Cl 2 + 2e - 2Cl Reductin RIG 2

3 Cmbinatin - Synthesis (the REDX prcess defined) 1 Fe + 1Cl 2 (g) 1 FeCl 2 Analyzing the half reactins Fe chlrine gas frms irn (II) chlride Fe 2+ Cl Cl Fe e - xidatin IL 1 Cl 2 + 2e - 2Cl Reductin RIG the cmbining electrns bth n the half reactant reactins side cancel the electrns n the prduct side 1 Fe + 1 Cl 2 (g) 1 FeCl 2 What reactant was xidized? 2 Mg Mg Mg lst electrns (g) Mg 2+ 2 magnesium metal slid xygen gas xygen gained electrns magnesium xide slid inic salt 3

4 What reactant was xidized? Irn metal lst electrns Fe 3+ Fe 2 Fe (g) 2 slid xygen gas xygen gained electrns Fe 3+ 1 Fe 2 3 irn (III) xide slid TM inic salt Dn t Cmbustin cmbustin leave as f a methanl, fractin, multiply CH 4 thrugh by x CH 4 + C + H 2 CH 4 + C + H 2 Cmbustin f ethanl, C 2 H 4 C 2 H C + H Cmbustin f frmaldehyde, CH 2 CH 2 + C C H 2 What reactant was xidized? 4

5 Nw balance the cmbustin f glucse (bld sugar) 1C 6 H ? Always balance xygens last 1 6 +? = 18 6C + 6H = ? 2 = 18 Nw slve fr? -6-6 Substract 6 frm each side? 2 = Divide each side by 2? = 6 Cmbinatin - Synthesis - PHTSYNTHESIS C + H 2 C 6 H chlrphyll catalyst 5