Question

At first, it seemed like the poisoned Russian agent might have ingested thallium in the form of thallium(I) sulfate, a rodenticide (rat poison), not allowed in the US and Western countries but still used in other countries. Thallium leads to hair loss. It also replaces potassium in important enzymes in the brain, muscles and skin. It takes 8.0 x 102 mg of thallium ion to kill an average adult. It took a bit of investigating to figure out that the agent was actually poisoned by polonium, a radioactive element, harmful only if it goes into the body. The radioactivity emitted by polonium, alpha particles, can be stopped by skin; but, if ingested, it gets into the blood stream, travels to organs and does lots of damage. The maximum safe body amount of polonium is 7 pg (picograms!) The agent was apparently poisoned with about 10 micrograms. To provide the minimum amount of thallium to kill the average adult, how many mL of 0.45 M solution of thallium(I) sulfate needs to be ingested?

Answer 1

The correct answer is 4.4 ml.

The mass of thallium required = 8.0 × 10² mg = 0.8 g

Molarity = 0.45 M

The moles of thallium can be determined by the formula mass / atomic mass

= 0.8 g / 204.38 g/mol

= 0.00391 moles

One mole of thallium sulfate gives two moles of thallium,

So, the number of moles of thallium needed = 0.00391 / 2 = 0.00196 moles

Volume of solution needed = moles / molarity

= 0.000196 moles / 0.45 M

= 4.35 ml or 4.4 ml