1. Balance equations Dalton Atomic model: In a chemical reaction, atoms only change the way that they are bound together with other atoms( page 49). For example: H + O → H-O (water)Dalton used hooks rather than line bonds. Electrolysis of water suggested water’s formula is actually H-O-H. There are 7 diatomic elemental gases: H 2, O 2, N 2, F 2, Cl 2, Br 2, and F 2. This leads to: H-H + H-H + O=O → H-O-H + H-O-H 4 H’s and 2 O’s are rearranged on each side. This balanced equation can be written as: 2 H 2 + O 2 → 2 H 2 O 2 moles of H 2 react with 1 mole of O 2 to form 2 moles of H 2 O.

2. Balance equations/solve problems Balance the following equations: 1.Al 2 S 3 + H 2 0  Al(OH) 3 + H 2 S 2.Bi 2 O 3 + C → Bi + CO 3.Cu 2 S + O 2 → Cu 2 O + SO 2 4.N 2 H 4 + Dinitrogen dioxide → Nitrogen gas + H 2 O 5. C 2 N 2 + H 2 O → H 2 C 2 O 4 + NH 3 6. CaSiO 3 + HF → SiF 4 + CaF 2 + H 2 O 7. Iron + hydrogen chloride → iron(II) chloride + hydrogen gas. 8. Iron + hydrogen chloride → iron(III) chloride + hydrogen gas 9. Phosphorus pentachloride + H 2 O → phosphoric acid + HCl 10. Sulfur hexafluoride reacts with water to form hydrogen sulfate and hydrogen fluoride. 11 Nitrogen dioxide reacts with water to form hydrogen nitrate and nitrogen monoxide (nitric oxide).

3. Balance equations/solve problems Solve the following problems: Be sure to correctly balance the equation. 1. Al 2 S 3 + H 2 0  Al(OH) 3 + H 2 S Calculate the moles of Al 2 S 3 that reacts with 456 g (1.0 pint )of water. ANS: 4.22 mole 2. Al 2 S 3 + H 2 0  Al(OH) 3 + H 2 S Calculate the mass of H 2 S that forms from 456 g of water. ANS: 432 g 3. Bi 2 O 3 + C → Bi + CO Calculate the mass of Bi 2 O 3 needed to form 1.26 X 10 -6 g Bi. ANS: 1.40 X 10 -6 g

4. Balance equations/solve problems Solve the following problems:Be sure to correctly balance the equation 1. Nitrogen dioxide reacts with water to form hydrogen nitrate and nitrogen monoxide (nitric oxide). Calculate the moles of hydrogen nitrate formed when 165 g of nitrogen dioxide react. ANS: 2.39 mol 2. Sulfur hexafluoride reacts with water to form hydrogen sulfate and hydrogen fluoride. Calculate the mass of hydrogen fluoride formed when 13.4 g of sulfur hexafluoride react. ANS: 11.0 g 3. Copper (II) sulfide reacts with oxygen gas to form copper (II) oxide and sulfur dioxide. Calculate the mass of copper (II) sulfide necessary to form 1.0 kg of copper(II)oxide. (= 1202 g) ANS: 1200 g CuS ← last 0 not sig.fig.

5. Balance equations/solve problems Coal (carbon) combines with oxygen gas (combustion) to form carbon dioxide and generate heat (kj). Natural gas (methane) combines with oxygen gas (combustion) to form carbon dioxide and water and generate heat (kj). 1. Write balanced equations showing the combustion of coal and natural gas with oxygen gas. 2. 1.0 kg of coal (carbon) produces 32800 kj. Calculate the energy produced by 1.0 mole of coal and add this energy to the product side of the equation. ANS: 394 kj 3. 650g of methane produces 32600 kj. Calculate the energy produced by 1.0 mole of methane and add this energy to the product side of the equation. ANS: 802 kj 4. Which reaction (coal or methane) releases the least carbon dioxide per kj of energy produced? HINT: Write the balanced chemical equation with the heat term.