Final answer:
To find the mass of methane produced from the decomposition of acetaldehyde, subtract the remaining moles of acetaldehyde from the initial amount and multiply the result by the molar mass of methane to get 81.6436 grams.
Step-by-step explanation:
The student is asking a question related to stoichiometry, a part of chemistry that deals with the calculation of reactants and products in chemical reactions. The decomposition of acetaldehyde to methane and carbon monoxide can be represented by the balanced equation CH3CHO(g) → CH4(g) + CO(g).
The student initially had 5.793 moles of acetaldehyde, and 0.703 moles remain after the reaction. To find out how many moles of methane were made, we calculate the difference, which is 5.793 moles - 0.703 moles = 5.090 moles of methane produced. The molar mass of methane (CH4) is approximately 16.04 g/mol. Thus, the mass of methane produced is 5.090 moles × 16.04 g/mol = 81.6436 grams.