A forensic chemist is given a white solid that is suspected of being pure cocaine (C1,H2,NO4, molar mass = 303.35 g/mol). She dissolves 1.22 + 0.01 g of the solid in 15.60 ±0.01 g benzene. The freezing point is lowered by 1.32 + 0.04°C. a. What is the molar mass of the substance? Assuming that the percent uncertainty in the calculated molar mass is the same as the percent uncertainty in the temperature change, calculate the uncertainty in the molar mass. b. Could the chemist unequivocally state that the substance is cocaine? For example, is the uncertainty small enough to distinguish cocaine from codeine (C13H,, NO, molar mass = 299.36 g/mol)? c. Assuming that the absolute uncertainties in the measurements of temperature and mass remain unchanged, how could the chemist improve the precision of her results?

Elements Of Electromagnetics
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A forensic chemist is given a white solid that is suspected of being pure cocaine (C17H21NO4 , molar mass = 303.35 g/mol). She dissolves 1.22 ± 0.01 g of the solid in 15.60 ± 0.01 g benzene. The freezing point is lowered by 1.32 ± 0.04°C.
a. What is the molar mass of the substance? Assuming that the percent uncertainty in the calculated molar mass is the same as the percent uncertainty in the temperature change, calculate the uncertainty in the molar mass.
b. Could the chemist unequivocally state that the substance is cocaine? For example, is the uncertainty small enough to distinguish cocaine from codeine (C18H21NO3, molar mass = 299.36 g/mol)?
c. Assuming that the absolute uncertainties in the measurements of temperature and mass remain unchanged, how could the chemist improve the precision of her results?

A forensic chemist is given a white solid that is suspected of being pure
cocaine (C1,H2,NO4, molar mass = 303.35 g/mol). She dissolves 1.22 +
0.01 g of the solid in 15.60 ±0.01 g benzene. The freezing point is
lowered by 1.32 + 0.04°C.
a. What is the molar mass of the substance? Assuming that the percent
uncertainty in the calculated molar mass is the same as the percent
uncertainty in the temperature change, calculate the uncertainty in the
molar mass.
b. Could the chemist unequivocally state that the substance is cocaine?
For example, is the uncertainty small enough to distinguish cocaine
from codeine (C13H,, NO, molar mass = 299.36 g/mol)?
c. Assuming that the absolute uncertainties in the measurements of
temperature and mass remain unchanged, how could the chemist
improve the precision of her results?
Transcribed Image Text:A forensic chemist is given a white solid that is suspected of being pure cocaine (C1,H2,NO4, molar mass = 303.35 g/mol). She dissolves 1.22 + 0.01 g of the solid in 15.60 ±0.01 g benzene. The freezing point is lowered by 1.32 + 0.04°C. a. What is the molar mass of the substance? Assuming that the percent uncertainty in the calculated molar mass is the same as the percent uncertainty in the temperature change, calculate the uncertainty in the molar mass. b. Could the chemist unequivocally state that the substance is cocaine? For example, is the uncertainty small enough to distinguish cocaine from codeine (C13H,, NO, molar mass = 299.36 g/mol)? c. Assuming that the absolute uncertainties in the measurements of temperature and mass remain unchanged, how could the chemist improve the precision of her results?
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