Supplemental packet page 117

This is a chemical recipe for the decomposition of water by electrolysis. productsreactants What did John Dalton in 1808 have to say about chemical reactions? 1. Chemical reactions involve just the simple rearrangement of atoms. 2. Atoms are conserved in a chemical reaction. In other words, atoms are not created nor destroyed in chemical reaction.

Is this true for the decomposition of water by electrolysis? Write the following opposite supplemental packet page 106

1. Chemical reactions involve just the simple rearrangement of atoms. 2. Atoms are conserved in a chemical reaction. In other words, atoms are not created nor destroyed in chemical reaction. This ture for the below decomposition of water by electrolysis. 4 hydrogen atoms 2 oxygen atoms Let’s see if John Dalton had assumed correctly.

36 grams H 2 O produces 4 grams H 2 and 32 grams O 2 Stoichiometry supplemental packet page 117

Stoichiometry supplemental packet page 118

Reduction is Gain, RIG (l)(g) 00 2H + + 2e - H 2 0 The battery supplies those electrons Remember hydrogen ions’s favorite charge in its combined state is: H +

(l)(g) Then what happened the oxygen atom in water? 00 So oxide ion must have lost electrons O 2- O 0 + 2e - Lost electrons in the electrolysis are attracted To the positive ca hode Oxidation is loss of electrons, OIL Remember oxygen ion’s favorite charge in its combined state is: O 2- 2-

O 2- O 0 + 2e - 2H + + 2e - H 2 0 Oxidation is Loss, OIL Reduction is Gain, RIG REDOX, is about the exchange of electrons. Summary: (l)(g) 00 Take the summation of both half-reactions affords the overall rxn below

Equilibrium off-balanced (unequal) reactant to productEquilibrium balance Precipitation saturation (solid formation) gas formation Up & Down Reflux like acid reflux (heart burn) Supplemental packet page 106

Don’t do this!!!! Supplemental packet page 106

2 2 1 In balancing, we would like the lowest whole number molar ratio. Where the number out in front is called a molar coefficient. Write this into our notes

1 1 2 But what if an individual balanced the magnesium first? 1212 The reaction is balanced, BUT there is a fractional molar coefficient. We must remove the fraction by multiplying through by In my opinion, the following is the easiest way to balance, if you: 1) always balance oxygens last; 2) then multiply by factor of 2, to remove any fractional molar coefficient that might be present in the balanced reaction.

Note: We are going for the lowest whole number Molar coefficient ratio

Finally, name the compounds and give physical states. (s) magnesium metal solid (g) oxygen gas (s) magnesium oxide solid ionic salt 432 (s) iron metal solid (g) oxygen gas (s) iron (III) oxide solid TM ionic salt

Always balance oxygens last 11 1 O O ? O 2 = 4 2? = 4 Combustion of methane gas

? O 2 = 7 Always balance oxygens last 12 2 O O = 7 3? Combustion of ethane gas

Always balance oxygens last 11 1 O O = 4 2? 1 O + ? O 2 = ? 2 = 4 Now solve for “?” ? 2 = 3 Substract one from each side 2 3 ? = Divide each side by 2 Combustion of methanol liquid

11 2? x 1 2 x x 12 x Combustion of methanol liquid

Now balance the combustion of glucose (blood sugar) Always balance oxygens last 16 1 O O 1O 6 + ? O 2 = 18 6? = ? 2 = 18 Now solve for “?” ? 2 = Substract 6 from each side ? = 6 22Divide each side by 2

Combination - Synthesis - PHOTOSYNTHESIS 6166 CO 2 + H 2 O C 6 H 12 O 6 + O 2 chlorophyll catalyst

C 2 H 6 O + O 2 CO 2 + H 2 O CH 2 O + O 2 CO 2 + H 2 O combustion CH 4 O + O 2 CO 2 + H 2 O x CH 4 O + O 2 CO 2 + H 2 O __ 2 Don’t leave as a fraction, multiply through by 2Combustion of methanol, CH 4 O Combustion of ethanol, C 2 H 4 O Combustion of formaldehyde, CH 2 O What reactant was oxidized?What reactant was reduced? C 4+ O 2–

Ionic salt transfer reactions in aqueous solution Ionic salt solubility in water All group I salts soluble, Li,Na,K All nitrate salts soluble All ammonium salts soluble,NH 4 + Driving forces for ion transfer, a force that makes the reaction go. Physical state formations: If a solid forms If a liquid forms If a gas forms Evidence for chemical change, ∆ Color change (tricky) Heat evolved (tricky) precipitation saturation (solids) If a liquid forms (heat evolved) If a gas forms (bubbles, odor) A + B - (aq) + C + D - (aq) AD(?) + BC(?) you’ll need to determine state based on some rules

Ionic salt transfer reactions in aqueous solution A + B - (aq) + C + D - (aq) AD(?) + BC(?) Common sense tells us to mix ionic solutions in order to have an reaction to occur. (we are not going to mix for the sake of mixing) Use of common sense tells us that, An acids mixed with a base (antacid) causes a neutralization. H + A - (aq) + M + OH - (aq) H 2 O (l) + MA(?) Use of common sense tells us that, An acids mixed with carbonate (HCO 3 - ) produces CO 2 water and salt H + A - (aq) + NaHCO 3 (aq) H 2 O (l) + NaA (aq) CO 2 (g)

A + B - (aq) + C + D - (aq) AD(?) + BC(?) Say the product names Now write the ions associated with each substance Ag + (NO 3 ) – Na + Cl - Ag + (NO 3 ) – Na + Cl - Now write formuals for the products AgCl + NaNO 3 Identify physical state in aqueous solution Solubility rules need to be applied. (s) (aq)

carbide ion X- charges nitride ion oxide ion fluoride phosphide ion sulfide ion chloride ion phosphate ion sulfate ion perchlorate ion borate ion carbonate ion nitrate ion

Fe o Fe e - Oxidation OIL 11 Fe (s) + Cl 2 (g) FeCl 2 (s) 111 Combination - Synthesis (the REDOX process defined) Analyzing the half reactions Cl 2 o + 2e - 2Cl – Reduction RIG Fe 2+ Cl – iron (II) chloridechlorine gasiron metalforms> plus

Fe o Fe e - Oxidation OIL Cl 2 o + 2e - 2Cl – Reduction RIG Fe (s) + Cl 2 (g) FeCl 2 (s) 111 Combination - Synthesis (the REDOX process defined) Analyzing the half reactions Fe 2+ Cl – iron (II) chloridechlorine gasiron metalforms combining both half reactions 1 Fe (s) + 1 Cl 2 (g) 1 FeCl 2 (s) the electrons on the reactant side cancel the electrons on the product side

What reactant was oxidized? (s) magnesium metal solid (g) oxygen gas (s) magnesium oxide solid ionic salt What reactant was reduced? Mg O O2OO2O Mg 2+ O 2– Mg o lost electrons Oxygen gained electrons

What reactant was oxidized? 432 (s) iron metal solid (g) oxygen gas (s) iron (III) oxide solid TM ionic salt What reactant was reduced? Fe 3+ O 2– Fe 3+ O 2– Fe O Iron metal lost electrons O2OO2O Oxygen gained electrons

Combustion of methanol in PLASTIC BOTTLE REDOX MID-TERM Fe + Cl 2 FeCl hydrogen atoms 2 oxygen atoms

SOLUBILITY in aqueous solutions BATTERY DEMO