Question

What is the mass of ^60Co in a cancer therapy transillumination unit containing 5.00 kCi of ⁶0Co?

a) 0.14 g
b) 0.28 g
c) 0.42 g
d) 0.56 g

Answer 1

The mass of 60Co in the transillumination unit can be calculated using the activity and the molar mass. The mass of 60Co is approximately 0.56 g. The correct answer is d) 0.56 g.

Step-by-step explanation:

The mass of 60Co in a cancer therapy transillumination unit containing 5.00 kCi of 60Co can be calculated using the activity of the sample and the molar mass of 60Co.

First, convert the activity from Curie (Ci) to Becquerel (Bq).

Then, use the molar mass of 60Co to calculate the number of moles, and finally, multiply by the molar mass to find the mass of 60Co in grams.

The molar mass of 60Co is 59.933822 g/mol.

Converting the activity from 5.00 kCi to Bq gives 1.85 × 1014 Bq. Using Avogadro's number (6.02214179 × 1023 atoms/mol), we can calculate the number of moles of 60Co, which is approximately 3.07 × 10-11 mol.

Finally, multiplying the number of moles by the molar mass gives the mass of 60Co, which is approximately 0.56 g.

Therefore, the correct answer is d) 0.56 g.