Chemistry
Chemistry
Problem
In a lab procedure, solid Na2CO3 is added to an aqueous solution of HCl, and the CO2(g) that forms is collected in a gas syringe. The student then uses the measured temperature and pressure of the gas to calculate the number of moles of CO2 and, from that value, the number of moles of Na2CO3 consumed. Which of the following best explains why the balanced chemical equation is essential for the second part of this calculation? a) It lists the physical states of all species, so the student can identify which substance is in the gas phase and therefore measured in the syringe. b) It shows which reactant is limiting, so the measured moles of CO₂ can be converted directly to the amount of consumed. c) It provides the mole ratio that links moles of CO₂ to moles of , ensuring conservation of atoms across the reaction. d) It contains the molar masses of the substances, making it possible to relate the moles of CO₂ to grams of .Intuitive explanation
The balanced equation reveals the mole ratio between reactants and products—specifically, how many moles of Na₂CO₃ correspond to each mole of CO₂ produced. Once you know moles of CO₂ from the gas measurement, you need that stoichiometric relationship to convert backward to moles of the original solid, which the equation provides directly.
Intuitive explanation
The balanced equation reveals the mole ratio between reactants and products—specifically, how many moles of Na₂CO₃ correspond to each mole of CO₂ produced. Once you know moles of CO₂ from the gas measurement, you need that stoichiometric relationship to convert backward to moles of the original solid, which the equation provides directly.