Final answer:
To find out how many grams of C2H5OH are used up, we convert 6.25 grams of O2 to moles, use the stoichiometric ratios from the balanced equation, and convert moles of C2H5OH to grams. The correct answer is 2.08 grams of C2H5OH, which is option A listed among the provided options.
Step-by-step explanation:
To calculate how many grams of C2H5OH are used up when 6.25 grams of O2 react according to the equation C2H5OH + 3O2 → 2CO2 + 3H2O, we need to use stoichiometry. First, we determine the molar masses of the reactants: the molar mass of O2 is approximately 32.00 g/mol and the molar mass of C2H5OH (ethanol) is about 46.07 g/mol. Using the stoichiometry of the balanced equation, we know that 3 moles of O2 react with 1 mole of C2H5OH.
Next, we convert the grams of O2 to moles: 6.25 g O2 * (1 mol O2 / 32.00 g O2) = 0.1953 mol O2. Since the ratio of O2 to C2H5OH is 3:1, there are 0.1953 mol O2 * (1 mol C2H5OH / 3 mol O2) = 0.0651 mol C2H5OH needed. Finally, we convert the moles of C2H5OH to grams: 0.0651 mol C2H5OH * (46.07 g C2H5OH / 1 mol C2H5OH) = 2.08 grams of C2H5OH.
Therefore, the correct answer is A of the provided options.