CHEM 11200 Lecture Notes - Lecture 3: Ionic Compound, Ampere, Chemical Formula

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lemonhedgehog555

19 Jul 2020

School

University of Chicago

Department

Chemistry

Course

CHEM 11200

Professor

Kozmin

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Document Summary

Mole kelvin celsius ampere liter/milliliter angstroms mol amount of substance. L/ml temperature temperature electric current volume length on atomic level. Molecular formula : gives the identities and numbers of atom in a particular molecule. Empirical formula : the reduced molecular formula to its lowest ratio. Molecular formula = c 2 h 6 o 2 ---> empirical formula = ch 3 o. Formula weight : the sum of the atomic weights in an ionic compound. Molecular weight : sum of the atomic weights in a molecular compound. Take the atomic mass of each element and multiply it by the number of atoms of that element found in the compound/molecule. Add all the sums together for each atom. One mole contains 6. 02 x 10 23 entities (molecules, atoms, etc. ) Multiply atomic weight to # atoms present for each present element. Take 100g and use known % to calculate amount of grams of each element.

Related Questions

Determine the empirical and molecular formulas of each of the following substances:

(a) Styrene, a compound substance used to make Styrofoam^® cups and insulation, contains 92.3% C and 7.7% H by mass and has a molar mass of 104 g/mol.

(b) Caffeine, a stimulant found in coffee, contains 49.5% C, 5.15% H, 28.9% N, and 16.5% O by mass and has a molar mass of 195 g/mol.

(c) Monosodium glutamate (MSG), a flavor enhancer in certain foods, contains 35.51% C, 4.77% H, 37.85% O, 8.29% N, and 13.60% Na, and has a molar mass of 169 g/mol.

Empirical formula of this compound is CH.

To determine the molecular formula, we need to find out how many times is molar mass higher than the mass of empirical formula:

Molecular formula is C₈H₈.

b) Empirical formula of caffeine:

Empirical formula of caffeine is C₄H₅N₂O. The sum of atomic masses from empirical formula is 97 g/mol.

Molecular formula of caffeine is 2 × empirical formula = C₈H₁₀N₄O₂

c) Empirical formula of MSG:

Empirical formula of MSG is C₅H₈NO₄Na. The sum of atomic masses of empirical formula is 169 g/mol, the same as molar mass. Empirical and molecular formula are identical.

cyanchimpanzee483

Determine the empirical and molecular formulas of each of the following substances:
(a) Ibuprofen, a headache remedy, contains 75.69% C, 8.80% H, and 15.51% O by mass, and has a molar mass of 206 g/mol.
(b) Cadaverine, a foul-smelling substance produced by the action of bacteria on meat, contains 58.55% C, 13.81% H, and 27.40% N by mass; its molar mass is 102.2 g/mol.
(c) Epinephrine (adrenaline), a hormone secreted into the bloodstream in times of danger or stress, contains 59.0% C, 7.1% H, 26.2% O, and 7.7% N by mass; its MW is about 180 amu.

Empirial formula of ibuprofene is calculated by multiplying obtained ratio with 2, and the result is C₁₃H₁₈O₂. The sum of atomic mass of C₁₃H₁₈O₂ is 206 g/mol. Molecular formula is the same as empirical.

Empirical formula of cadaverine, C₅H₁₄N₂ is obtained by multiplying the moles of each atom with 2 in order to obtain the whole numbers. The weight of empirical formula is 102 g/mol, so it is at the same time the molecular formula.

c) 59.0% C, 7.1% H, 26.2% O, and 7.7% N

Empirical formula of adrenaline is C₉H₁₃NO₃, and its mass is 183 g/mol. Since MW of hormone is about 180, molecular formula is the same as empirical formula.

cyantermite944

CHEM 11200 Lecture Notes - Lecture 3: Ionic Compound, Ampere, Chemical Formula

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