Final answer:
To convert 8.00 x 10^19 molecules of HCN to grams, calculate the number of moles by dividing by Avogadro's number and then multiply by the molar mass of HCN (27.02 g/mol).
Step-by-step explanation:
To convert 8.00 x 1019 molecules of HCN to grams, you first need to understand Avogadro's number, which is the number of particles in one mole of substance: 6.022 x 1023 molecules/mol. Using this information, you can calculate the number of moles of HCN:
Number of moles = (8.00 x 1019) / (6.022 x 1023) moles
Once the number of moles is determined, you use the molar mass of HCN to find the mass in grams. The molar mass of HCN is the sum of the atomic masses of Hydrogen (H), Carbon (C), and Nitrogen (N), which are approximately 1.008 g/mol, 12.01 g/mol, and 14.01 g/mol, respectively. Therefore, the molar mass of HCN is 27.02 g/mol.
Finally, you multiply the number of moles of HCN by its molar mass to get the mass in grams:
Mass of HCN in grams = (Number of moles) x (27.02 g/mol)
Make sure to use dimensional analysis/conversion factors properly and to round your final answer to the correct number of significant figures as dictated by the initial number of molecules given.