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Balancing c hemical e quations

Balancing c hemical e quations. Learning Objectives: State the Law of conservation of mass Convert word equations into symbol equations Balance symbol equations. The Limestone cycle.

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Balancing c hemical e quations

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  1. Balancing chemical equations Learning Objectives: State the Law of conservation of mass Convert word equations into symbol equations Balance symbol equations.

  2. The Limestone cycle When --------- (calcium carbonate) is heated strongly, it ---------- to give solid quicklime (calcium oxide) and carbon ------- gas. When a small amount of ----- is added to quicklime it gives ------ lime (calcium hydroxide). If a lot of water is added to the slaked lime a solution of ---- ----- or calcium hydroxide is formed. If ------ ------- is bubbled through lime water, --------- is formed again, along with water.

  3. The Limestone cycle equations Complete the word &symbol equations for the limestone cycle Calcium carbonate  …………… …………… (s) + …………… …………… (g) CaCO3 …………… (s) + …………… …………… (g) Calcium oxide (s) + ………………… (l)  ………………… ………………… (s) ………… (s) + ………………… (l)  Ca(OH)2(s) Calcium hydroxide(aq) + …………… ……………(g)…………… ……………(s) + water(l) Ca(OH)2(aq)+ ………………… (g)  ………………… (s) + H2O (l)

  4. Balancing chemical equations In a chemical reaction we do not gain or lose any atoms, they just rearrange. The Law of conservation of mass states that…. Mass of reactants = Mass of products In a chemical reaction there must be the same numbers of ATOMS before and after. The equation must balance

  5. Hydrogen gas (H2) is a fuel. When it is burned in air it combines with oxygen (O2) to form molecules of water (H2O) . 1) Write the word equation: Hydrogen + oxygen  water 2) Replace the words with chemical and state symbols: H2(g) + O2(g)  H20 (l) 3) Count up the numbers of atoms on the reactant and product sides. 4) Balance equation so there are the same number of atoms on each side of the equation.

  6. H2(g) + O2(g)  H20 (l) 1 molecule of hydrogen gas contains __hydrogen atoms. 1 molecule of water contains 2 hydrogen atoms and 1 _________ atom. When we balance a chemical equation we ________change the subscript numbers in the chemical formula as this would change it into a different chemical! We can only change the number of __________in the equation. 2H2(g) + O2(g)  2H20 (l)

  7. Equation balancing practice Now try to balance these equations: (finish for H/W) • H2 +Br2HBr • Ca + O2CaO • MgCO3 + HCl MgCl2 + H2O + CO2 • Fe + O2 Fe2O3 • Fe + Cl2 FeCl3 • C2H6 + O2 CO2 + H2O • K +H2O KOH + H2 • NaNO3 NaNO2 + O2 • CH4 + O2 CO2 + H2O • Pb(NO3)2PbO + NO2 + O2

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