Stoichiometry and Chemical Reactions

In the combustion of octane (C8H18), the balanced equation reflects the stoichiometry of the reaction, where octane reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). The coefficients indicate that two molecules of octane react with twenty-five molecules of oxygen to yield sixteen molecules of carbon dioxide and eighteen molecules of water. This balance ensures that the number of atoms of each element is conserved on both sides of the equation, following the law of conservation of mass.

In the combustion reaction of octane (C8H18), the stoichiometry indicates that 2 moles of C8H18 produce 16 moles of CO2. To find the amount of CO2 produced from 22.0 moles of C8H18, we set up a proportion based on the reaction ratio. For every 2 moles of C8H18, 16 moles of CO2 are generated. Thus, for 22.0 moles of C8H18, the calculation is: (22.0 moles C8H18) × (16 moles CO2 / 2 moles C8H18) = 176 moles CO2.

In the combustion of octane (C8H18), the balanced chemical equation shows that 2 moles of C8H18 produce 16 moles of CO2. This mole ratio, 16:2, simplifies to 8:1, indicating that for every mole of C8H18, 8 moles of CO2 are produced. Therefore, to convert moles of C8H18 to moles of CO2, the ratio of 16 mol CO2 to 2 mol C8H18 is used, reflecting the stoichiometric relationship in the reaction.

To calculate the molar mass of TiO2, we need to sum the atomic masses of titanium (Ti) and oxygen (O). Titanium has an atomic mass of approximately 47.87 g/mol, and oxygen has an atomic mass of about 16.00 g/mol. Since there are two oxygen atoms in TiO2, the calculation is as follows: 47.87 g/mol (Ti) + 2 × 16.00 g/mol (O) = 79.87 g/mol. This total gives us the molar mass of titanium dioxide, which is essential for stoichiometric calculations in the reaction provided.

In the reaction TiO2(s) + 2 C(s) → Ti(s) + 2 CO(g), the stoichiometry indicates that 1 mole of TiO2 reacts with 2 moles of C. To determine the limiting reactant, we need to calculate the moles of each reactant. The molar mass of C is approximately 12 g/mol, so 28.6 kg of C corresponds to about 2383 moles. The molar mass of TiO2 is about 80 g/mol, so 88.2 kg of TiO2 corresponds to about 1102 moles. Since 1102 moles of TiO2 would require 2204 moles of C, there isn’t enough C, making C the limiting reactant.

Percent yield measures the efficiency of a chemical reaction by comparing the actual amount of product obtained to the maximum possible amount (theoretical yield) that could be produced under ideal conditions. It is calculated by taking the actual yield, dividing it by the theoretical yield, and then multiplying the result by 100 to express it as a percentage. This formula helps chemists assess how well a reaction proceeds and identify any losses during the process.

To determine how many grams of N2 can be produced, first, calculate the moles of NH3 and CuO. For 9.05 g of NH3, the moles are 0.532 (9.05 g / 17.03 g/mol). For 45.2 g of CuO, the moles are 0.568 (45.2 g / 79.55 g/mol). The reaction shows that 2 moles of NH3 react with 3 moles of CuO. NH3 is the limiting reactant, as it produces less N2. Using stoichiometry, 0.532 moles of NH3 yield 0.266 moles of N2. Converting this to grams gives 7.46 g (0.266 moles × 28.02 g/mol).

The theoretical yield represents the maximum quantity of product that can be obtained from a chemical reaction, calculated using the amount of the limiting reactant. The limiting reactant is the substance that is entirely consumed first during the reaction, thus determining the extent of the reaction and the amount of product formed. Other reactants may be present in excess, but they do not influence the total yield since the reaction cannot proceed beyond the availability of the limiting reactant.

In the complete combustion of octane (C8H18), the balanced chemical equation is: 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O. From this equation, it can be seen that for every 25 moles of O2 consumed, 18 moles of H2O are produced. This establishes a mole ratio of O2 to H2O of 25:18, confirming the statement is true.