Final answer:
To find the mass of a 30.0 kmol sample, the molar mass of the substance is required. If the substance is potassium (K), with a molar mass of 39.10 g/mol, the mass would be 1173.0 kg by multiplying 30.0 kmol by the molar mass and converting kmol to mol.
Step-by-step explanation:
To calculate the mass of a sample containing 30.0 kmol of a substance, you need to know the molar mass of the substance. The molar mass is often found on the periodic table and is expressed in g/mol. As an example, potassium (K) has a molar mass of 39.10 g/mol, as per the periodic table. If the substance in question were potassium, you would calculate the mass by multiplying the number of moles by the molar mass:
Mass = (number of moles) x (molar mass)
Mass = (30.0 kmol) x (39.10 g/mol) x (1000 mol/kmol)
Mass = (30.0 x 1000 mol) x (39.10 g/mol)
Mass = (30000 mol) x (39.10 g/mol)
Mass = 1173000 g
Mass = 1173.0 kg
Therefore, for a substance with the molar mass of potassium, a 30.0 kmol sample would have a mass of 1173.0 kg.