Final answer:
To find the mass of 0.69 mol of calcium cyanide, we calculate the molar mass of Ca(CN)2 and multiply by the number of moles, resulting in approximately 64 grams.
Step-by-step explanation:
To calculate the mass of 0.69 mol of calcium cyanide (Ca(CN)2), we first need to determine the molar mass of Ca(CN)2. Calcium (Ca) has an atomic mass of approximately 40.08 g/mol, and cyanide (CN) has a mass of about 26.02 g/mol (12.01 for carbon and 14.01 for nitrogen). Since there are two cyanide groups in calcium cyanide, the total molar mass of Ca(CN)2 is 40.08 g/mol + 2(26.02 g/mol) = 92.12 g/mol.
To find the mass in grams, we multiply the number of moles by the molar mass:
0.69 mol × 92.12 g/mol = 63.56 g
This value is closest to option a. 64 g, which is the amount of calcium cyanide contained in 0.69 mol.