Age 16 to 18 Challenge Level:
Each compound contributes to the
total pressure in her lungs, known as the partial pressure. Can you
work out the partial pressure that each of the compounds
Make sure you consider the moles of "air" molecules present in
Ellie's lungs which also contribute to the partial pressure.
What is the density of the
cigarette smoke containing air in her lungs?
Make sure you take into account the masses of the components of
alveolar air as well as the unusual components of the smoke given
What is the average concentration
of nicotine in Ellie's blood given that systolic blood pressure is
120 mmHg, the diastolic blood pressure is 80 mmHg?
An equation is required that links pressure and volume as well as
number of moles. Also consider the value of blood pressure compared
to atmospheric pressure. The conversion from mmHg to Pa has been
provided earlier in the question.
How long does it take for levels
of nicotine to drop below the 200 ng/ml detectable level so that
Ellie can cheat her test?
Nicotine uptake into the blood stream is rapid compared with its
half-life. This can be seen by doing a rough calculation. You might
approximate the uptake to be instantaneous in your
Assuming that none of these
dangerous compounds is absorbed into the blood stream
over this period, what is the percentage of dangerous compounds in
the alveolar air for Ellie and her brother, Pete, after the last
Consider how the percentage of dangerous compounds varies with the
first few inward and outward breaths. Can you see any