Problem 44b
At least 25 mg of tetrahydrocannabinol (THC), the active ingredient in marijuana, is required to produce intoxication. The molecular formula of THC is C21H30O2. How many molecules?
Problem 45a
Give the empirical formula of each of the following compounds if a sample contains a.0.0130 mol C, 0.0390 mol H, and 0.0065 mol O
Problem 45b
Give the empirical formula of each of the following compounds if a sample contains b.11.66 g iron and 5.01 g oxygen
Problem 45c
Give the empirical formula of each of the following compounds if a sample contains c.40.0% C, 6.7% H, and 53.3% O by mass.
Problem 46a
Determine the empirical formula of each of the following compounds if a sample contains a. 0.104 mol K, 0.052 mol C, and 0.156 mol O;
Problem 46b
Determine the empirical formula of each of the following compounds if a sample contains b. 5.28 g Sn and 3.37 g F;
Problem 46c
Determine the empirical formula of each of the following compounds if a sample contains c. 87.5% N and 12.5% H by mass.
Problem 47a
Determine the empirical formulas of the compounds with the following compositions by mass: a. 10.4% C, 27.8% S, and 61.7% Cl
Problem 47b
Determine the empirical formulas of the compounds with the following compositions by mass: b. 21.7% C, 9.6% O, and 68.7% F
Problem 48a
Determine the empirical formulas of the compounds with the following compositions by mass: a. 55.3% K, 14.6% P, and 30.1% O
Problem 48c
Determine the empirical formulas of the compounds with the following compositions by mass: c. 62.1% C, 5.21% H, 12.1% N, and the remainder O
Problem 49
A compound whose empirical formula is XF3 consists of 65% F by mass. What is the atomic mass of X?
Problem 50
The compound XCl4 contains 75.0% Cl by mass. What is the element X?
Problem 51
What is the molecular formula of each of the following compounds? (a) empirical formula CH, molar mass 5 78.0 g/mol (b) empirical formula NH2Cl, molar mass = 51.5 g/mol
Problem 52a
What is the molecular formula of each of the following compounds? (a) empirical formula HCO2, molar mass = 90.0 g/mol
Problem 52b
What is the molecular formula of each of the following compounds? (b) empirical formula C2H4O, molar mass = 88.0 g/mol
Problem 53a
Determine the empirical and molecular formulas of each of the following substances: (a) Styrene, a compound 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.
Problem 53b
Determine the empirical and molecular formulas of each of the following substances: (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.
Problem 53c
Determine the empirical and molecular formulas of each of the following substances: (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.
Problem 54a
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.
Problem 54b
Determine the empirical and molecular formulas of each of the following substances: (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.
Problem 54c
Determine the empirical and molecular formulas of each of the following substances: (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 molar mass is about 180 u.
Problem 55a
(a) Combustion analysis of toluene, a common organic solvent, gives 5.86 mg of CO2 and 1.37 mg of H2O. If the compound contains only carbon and hydrogen, what is its empirical formula?
Problem 55b2
(b) Menthol, the substance we can smell in mentholated cough drops, is composed of C, H, and O. A 0.1005-g sample of menthol is combusted, producing 0.2829 g of CO2 and 0.1159 g of H2O. What is the empirical formula for menthol? If menthol has a molar mass of 156 g/mol, what is its molecular formula?
Problem 56a
(a) The characteristic odor of pineapple is due to ethyl butyrate, a compound containing carbon, hydrogen, and oxygen. Combustion of 2.78 mg of ethyl butyrate produces 6.32 mg of CO2 and 2.58 mg of H2O. What is the empirical formula of the compound?
Problem 56b
(b) Nicotine, a component of tobacco, is composed of C, H, and N. A 5.250-mg sample of nicotine was combusted, producing 14.242 mg of CO2 and 4.083 mg of H2O. What is the empirical formula for nicotine? If nicotine has a molar mass of 160 ± 5 g/mol, what is its molecular formula?
Problem 57a
Valproic acid, used to treat seizures and bipolar disorder, is composed of C, H, and O. A 0.165-g sample is combusted to produce 0.166 g of water and 0.403 g of carbon dioxide. What is the empirical formula for valproic acid?
Problem 58a
Propenoic acid, C3H4O2, is a reactive organic liquid that is used in the manufacturing of plastics, coatings, and adhesives. An unlabeled container is thought to contain this liquid. A 0.275-g sample of the liquid is combusted to produce 0.102 g of water and 0.374 g carbon dioxide. Is the unknown liquid propenoic acid? Support your reasoning with calculations.
Problem 59
Washing soda, a compound used to prepare hard water for washing laundry, is a hydrate, which means that a certain number of water molecules are included in the solid structure. Its formula can be written as Na2CO3 # xH2O, where x is the number of moles of H2O per mole of Na2CO3. When a 2.558-g sample of washing soda is heated at 125 C, all the water of hydration is lost, leaving 0.948 g of Na2CO3. What is the value of x?
Problem 60
Epsom salts, a strong laxative used in veterinary medicine, is a hydrate, which means that a certain number of water molecules are included in the solid structure. The formula for Epsom salts can be written as MgSO4 # xH2O, where x indicates the number of moles of H2O per mole of MgSO4. When 5.061 g of this hydrate is heated to 250 C, all the water of hydration is lost, leaving 2.472 g of MgSO4. What is the value of x?
Ch.3 - Chemical Reactions and Reaction Stoichiometry