Concept explainers
Tetrodotoxin is a toxic chemical found in fugu pufferfish, a popular but rare delicacy in Japan. This compound has an LD50 (the amount of substance that is lethal to 50.% of a population sample) of 10.μg per kg of body mass. Tetrodotoxin is 41.38% carbon by mass, 13.16% nitrogen by mass, and 5.37% hydrogen by mass, with the remaining amount consisting of oxygen. What is the empirical formula of tetrodotoxin? If three molecules of tetrodotoxin have a mass of 1.59 × 10−21 g, what is the molecular formula of tetrodotoxin? What number of molecules of tetrodotoxin would be the LD50 dosage for a person weighing 165 lb?
Interpretation: The empirical formula, molecular formula and the number of molecules of Tetrodotoxin are to be calculated.
Concept introduction: The empirical formula of an element is defined as the simplest formula that expresses the percentage composition of the element and the molecular formula of an element defines the total number of atoms present in a molecule.
To determine: The empirical formula, molecular formula and the number of molecules of Tetrodotoxin.
Answer to Problem 192IP
The empirical and molecular formula of Tetrodotoxin is
Explanation of Solution
Explanation
Given
The mass percent of carbon is
The mass percent of nitrogen is
The mass percent of hydrogen is
The remaining amount consists of oxygen. The mass percent of oxygen is calculated as,
Substitute the value of mass percent of carbon, nitrogen and hydrogen in the above expression, the mass percent of oxygen is calculated.
The mass percent of oxygen is
Therefore,
Mass of sample is
Mass of carbon is
Mass of nitrogen is
Mass of hydrogen is
Mass of oxygen is
The molar mass of carbon is
The molar mass of nitrogen is
The molar mass of hydrogen is
The molar mass of oxygen is
The number of moles is calculated by the formula,
Substitute the value of the given mass and the molar mass, to calculate the number of moles of carbon, nitrogen, hydrogen, and oxygen in the above equation.
For carbon,
For nitrogen,
For hydrogen,
For oxygen,
The calculated values are divided by the smallest number of moles to determine the simplest whole number ratio of moles of each constituent.
For carbon
For nitrogen
For hydrogen
For oxygen
Multiply each of the numbers by
So the empirical formula of Tetrodotoxin is
Three molecules of Tetrodotoxin has a mass of
The molar mass is the mass of one mole or
The molar mass of Tetrodotoxin is calculated by using the expression,
Substitute the value of mass and number of molecules of Tetrodotoxin the above expression, the molar mass of Tetrodotoxin is calculated.
The empirical formula mass of Tetrodotoxin is calculated as,
Since both are almost equal the empirical formula is equal to the molecular formula.
So the molecular formula of Tetrodotoxin is
The conversion of
Therefore, the conversion of
Weight of person is
The conversion of
Therefore, the conversion of
The weight of person is calculated as,
The mass of
One mole of Tetrodotoxin has a mass of
So molecules of Tetrodotoxin are calculated by using the expression.
Substitute the value of Mass and Molar mass of Tetrodotoxin in the above expression.
Hence, the molecules of Tetrodotoxin in
Conclusion
The empirical and molecular formula of Tetrodotoxin is
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Chapter 3 Solutions
Chemistry
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