#### Moles And Stoichiometry

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During a laboratory activity, appropriate safety equipment was used and safety procedures were followed. A laboratory technician heated a sample of solid KClO3 in a crucible to determine the percent composition by mass of oxygen in the compound. The unbalanced equation and the data for the decomposition of solid KClO3 are shown below.

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Thermal energy is absorbed as chemical reactions occur during the process of baking muffins. The batter for muffins often contains baking soda, NaHCO3(s), which decomposes as the muffins are baked in an oven at 200.°C. The balanced equation below represents this reaction, which releases CO2(g) and causes the muffins to rise as they bake. The H2O(ℓ) is released into the air of the oven as it becomes a vapor.

2NaHCO3(s) + heat → Na2CO3(s) + H2O(ℓ) + CO2(g)

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A sample of seawater is analyzed. The table below gives the concentration of some ions in the sample.

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Baking soda, NaHCO3, can be commercially produced during a series of chemical reactions called the Solvay process. In this process, NH3(aq), NaCl(aq), and other chemicals are used to produce NaHCO3(s) and NH4Cl(aq).

To reduce production costs, NH3(aq) is recovered from NH4Cl(aq) through a different series of reactions. This series of reactions can be summarized by the overall reaction represented by the unbalanced equation below.

NH4Cl(aq) + CaO(s) → NH3(aq) + H2O(ℓ) + CaCl2(aq)

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One process used to manufacture sulfuric acid is called the contact process. One step in this process, the reaction between sulfur dioxide and oxygen, is represented by the forward reaction in the system at equilibrium shown below.

2SO2(g) + O2(g) ⇌ 2SO3(g) + 394 kJ

A mixture of platinum and vanadium(V) oxide may be used as a catalyst for this reaction. The sulfur trioxide produced is then used to make sulfuric acid.

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