Chemistry Problem Solving Examples for Mole Calculations
Explore step-by-step examples in chemistry for mole calculations involving different compounds such as octane, isohexane, and cocaine. Learn how to convert grams to moles and vice versa, determining the number of moles and grams of specific elements within compounds. Enhance your understanding of stoichiometry and molecular formulas in a simplified manner.
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Homework 6 posted; due Friday 27 October Exam 2: Monday 30 October review day is Friday Moles suck the big one
`body parts example 2a : Weight moles first, then mol Octane = C8H18 How many moles of octane contain 24 grams of C (at. wt. = 12 g/mol)? Step 1) Convert grams C to moles C (all roads lead through moles divide up) Mol 24 g 12 g/mol C = 2 moles C
`body parts example 2a : (continued) Octane = C8H18 How many moles of octane contain 24 grams of C (at. wt. = 12 g/mol)? Step 2) 2 moles C => how many moles octane? 1 mol octane = x 8 mol C 2 (body parts relationship ?) x= 2/8=0.25 moles octane
Isohexane has the formula C6H14. How many moles of isohexane are formed with 24 grams of C (1 mol C=12 g) A. 0.333 moles isohexane B. 2 moles isohexane C. 0.1667 moles isohexane D. 3 moles isohexane E. Stoichiometry blows F. None of the above 0% 0% 0% 0% 0% 0% 2 moles isohexane 3 moles isohexane 0.333 moles isohexane 0.1667 moles isohexane Stoichiometry blows F. None of the above
`body parts example 2b : Octane = C8H18 How many g of C (at. wt. = 12 g/mol) are in 0.09375 mol of octane ? Step 1) 8 C 1 mol octane 0.09375 (body parts relationship ?) = x x= 8*0.09375=0.75 mol C
`body parts example 2b(cont.)_ : Octane = C8H18 How many g of C (at. wt. = 12 g/mol) are in 0.09375 mol of octane ? Step 2) Multiply down (convert x=0.75 mol C g C) 0.75 mol *12 g/mol =9 grams C
The molecular formula for cocaine is C17H21NO4 and has a molecular mass of 303.4 g/mol. How many grams of O are in 0.03125 mol of cocaine. The atomic mass of O=16 g/mol 25% 25% 25% 25% A. 2.0 g B. 0.50 g C. 9.5 g D. 19.0 g 2.0 g 9.5 g 19.0 g 0.50 g
`body parts example 3a : Weight moles , then mol Octane = C8H18 (MW=114) How many grams of H are in 10 grams of Octane ? (1 mole H=1 g H) Step 1) Convert grams octane to moles octane All roads lead through moles; divide up Mol weight 10 g 114 g/mol = 0.0877 mol octane
`body parts example 3 : Weight moles , then mol Octane = C8H18 (MW=114) How many grams of H are in 10 grams of Octane ? (1 mole H=1 g H) Step 1) Convert grams octane to moles octane All roads lead through moles; divide up Mol weight 10 g 114 g/mol = 0.0877 mol octane
`body parts example 3 (continued) : Octane = C8H18 (MW=114) How many grams of H are in 10 grams of Octane ? (1 mole H=1 g H) Step 2) Relate moles H to moles octane (body parts relationship ?) 14 mol H = x 1 octane 0.0877 x= 14*0.0877=1.228 mol H
`body parts example 3 (continued) : Octane = C8H18 (MW=114) How many grams of H are in 10 grams of Octane ? (1 mole H=1 g H) Step 3) convert moles H to grams H (multiply down) 1.228 mol H * 1 g H/mol=1.228 mol H
Isohexane has the formula C6H14. How many grams of H (at. Wt. = 1 g/mol) are combined in 300 grams of C6H14 (MW=86 g/mol) A. 36.84 g H B. 1.32 g H C. 0.249 g H D. 0.020 g H E. 48.84 g H 91% = x 1 mol octane 0.09375 9% 0% 0% 0% 1.32 g H 36.84 g H 48.84 g H 0.249 g H 0.020 g H
`body parts example 3b : Weight moles , then mol Octane = C8H18 (MW=114) How many grams of octane form from from 2.368 g H? (1 mole H=1 g H) Step 1) Convert grams H to moles H All roads lead through moles; divide up Mol weight 2.368 g H 1 g/mol = 2.368 mol H
`body parts example 3 (continued) : Octane = C8H18 (MW=114) How many grams of octane form from from 2.368 g H? (1 mole H=1 g H) Step 2) Relate moles H to moles octane (body parts relationship ?) 1 mol octane = x 18 mol H 2.368 x= 2.368/18=0.13155 mol octane
`body parts example 3 (continued) : Octane = C8H18 (MW=114) How many grams of octane form from from 2.368 g H? (1 mole H=1 g H) Step 3) convert moles octane to grams octane (multiply down) 0.13155 mol octane*114 g/mol=15 g
Royhypnol or`Roofies, the date rape drug, has the chemical formula C16H12FN3O3 and a molecular mass of 313.3 g/mol. How many grams of Roofie contain 3.676 g of C (atomic mass =12 g/mol) 25% 25% 25% 25% A. 96.97 g B. 22.53 g C. 6.00 g D. 60.0 g 60.0 g 6.00 g 96.97 g 22.53 g
Mole Body Part Calculations level 2: More practice, practice, practice 1)mole to mole: how many moles of O are present in 0.1666 mole of C6 H12O6? 1 mol O 2)mole to mole how many moles of C6H12O6 can be made with 12 mole of O ? 2 moles C6H12O6
Mole Calculations: part 2 (cont.) 3) weight to moles how many moles of C6H12O6 in a sample containing 216 g C ? 3 mol 4)moles to weight how many grams of C6H12O6 are formed with 0.2666 mol H? = 4 g
Mole Calculations: part 2 (cont.) 5) moles to molecules how many molecules of O are present in 0.8333 mol of C6 H12O6? =5*1023 6) molecules to moles how many moles of C6 H12O6 are formed from 4.32*1025 atoms of H ? 6 moles
Mole Calculations: part 2 (cont.) 7) mass to molecules: how many molecules of C6 H12O6 form from 84 g of C ? 7 *1023 molecules ofC6H12O6 8) atoms to mass: how many grams of H are combined with 2.4*1024 atoms of O in C6H12O 6 ? 8 grams H
