Final answer:
To determine the concentration of amphetamine in contact with 20.0°C air, we can use the Clausius-Clapeyron equation to find the vapor pressure and convert it to concentration.
Step-by-step explanation:
To determine the concentration of amphetamine in contact with 20.0°C air, we need to calculate the vapor pressure of amphetamine at 20.0°C using the given boiling point data at different pressures.
Using the Clausius-Clapeyron equation, we can express the relationship between vapor pressure and temperature:
P1/P2 = exp[(ΔHvap/R)(1/T2 - 1/T1)]
Using the data provided, we can substitute the boiling points and pressure values to solve for ΔHvap:
201.0°C --> 760.0 torr
83.0°C --> 13.0 torr
Plugging in the values into the equation and rearranging to solve for ΔHvap:
ΔHvap = (R x ln(P2/P1))/(1/T2 - 1/T1)
where R is the ideal gas constant and ln is the natural logarithm.
Once we have ΔHvap, we can use it to calculate the vapor pressure of amphetamine at 20.0°C. Then, using the ideal gas equation, we can convert the vapor pressure to concentration in g/m³.