# Gravimetric Stoichiometry Stoichiometry a measure of the relative proportions of the elements that take part in a chemical reaction 4 Al (s) + 3 O2 (g)

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Gravimetric Stoichiometry

Stoichiometry a measure of the relative proportions of the elements that take part in a chemical reaction 4 Al (s) + 3 O2 (g) = 2 Al2O3 (s) 6.49 g ? mol 26.98 g/mol

Stoichiometry a measure of the relative proportions of the elements that take part in a chemical reaction 4 Al (s) + 3 O2 (g) = 2 Al2O3 (s) 6.49 g ? mol 26.98 g/mol n Al = m/M = 6.49g/26.98g/mol = 0.2405485 mol n O 2 = n Al x mole ratio

Stoichiometry a measure of the relative proportions of the elements that take part in a chemical reaction 4 Al (s) + 3 O2 (g) = 2 Al2O3 (s) 6.49 g ? mol 26.98 g/mol nAl = m/M = 6.49g/26.98g/mol = 0.2405485 mol nO2 = nAl x mole ratio 0.2405485 mol Al x 3 mol O 2 4 mol Al 0.1804114 mol O 2 0.180 mol O 2 *example from http://www.cdli.ca/courses/chem2202/unit01_org02_ilo03/b_activity.html

Gravimetric Stoichiometry Gravimetric stoichiometry is stoichiometry with the answer expressed in mass. n Al 2 O 3 = n O 2 x mole ratio =0.1804 mole O 2 x 2 mol Al 2 O 3 3 mol O 2 = 0.1202666 mol Al 2 O 3

Gravimetric Stoichiometry Gravimetric stoichiometry is stoichiometry with the answer expressed in mass. nAl2O3 = nO2 x mole ratio =0.1804 mole O2 x 2 mol Al2O3 3 mol O2 = 0.1202666 mol Al2O3 m Al 2 O 3 = n x M = 0.1202666 mol x 101.96 g/mol =12.262389g =12.26g of Al 2 O 3 *example from http://www.cdli.ca/courses/chem2202/unit01_org02_ilo03/b_activity.html

Gravimetric Stoichiometry 1) Which word is most closely associated with meaning of the term gravimetric? A ) density B ) mass C ) mole D ) volume 2) Which device is best suited to obtaining a specific mass of a chemical species? A ) balance B ) beaker C ) flask D ) graduated cylinder

Gravimetric Stoichiometry 1) Which word is most closely associated with meaning of the term gravimetric? A ) density B ) mass C ) mole D ) volume 2) Which device is best suited to obtaining a specific mass of a chemical species? A ) balance B ) beaker C ) flask D ) graduated cylinder

Gravimetric Stoichiometry 1) Which word is most closely associated with meaning of the term gravimetric? A ) density B ) mass C ) mole D ) volume 2) Which device is best suited to obtaining a specific mass of a chemical species? A ) balance B ) beaker C ) flask D ) graduated cylinder

Gravimetric Stoichiometry 3) What mass of aluminum oxide can be produced from the complete reaction of 0.482 mol of oxygen gas? 4Al (s) + 3O (g) = 2Al 3 O 2 A ) 13.8 g B ) 32.8 g C ) 49.1 g D ) 73.7 g 4) Calculate the number of moles of hydrogen gas that should be produced from the complete reaction of 3.93g of zinc metal. Zn (s) + 2HCl (aq) = H 2(g) + ZnCl 2(aq) A ) 0.0601 mol B ) 3.93 mol C ) 16.6 mol D ) 257 mol

Gravimetric Stoichiometry 3) What mass of aluminum oxide can be produced from the complete reaction of 0.482 mol of oxygen gas? 4Al (s) + 3O (g) = 2Al 3 O 2 A ) 13.8 g B ) 32.8 g C ) 49.1 g D ) 73.7 g 4) Calculate the number of moles of hydrogen gas that should be produced from the complete reaction of 3.93g of zinc metal. Zn (s) + 2HCl (aq) = H 2(g) + ZnCl 2(aq) A ) 0.0601 mol B ) 3.93 mol C ) 16.6 mol D ) 257 mol

Gravimetric Stoichiometry 3) What mass of aluminum oxide can be produced from the complete reaction of 0.482 mol of oxygen gas? 4Al (s) + 3O (g) = 2Al 3 O 2 A ) 13.8 g B ) 32.8 g C ) 49.1 g D ) 73.7 g 4) Calculate the number of moles of hydrogen gas that should be produced from the complete reaction of 3.93g of zinc metal. Zn (s) + 2HCl (aq) = H 2(g) + ZnCl 2(aq) A ) 0.0601 mol B ) 3.93 mol C ) 16.6 mol D ) 257 mol

Gravimetric Stoichiometry Use the following information to answer questions # 5-7: The Chemistry recipe for S’mores is : 2 graham crackers + 4 marshmallows + 3 pieces of chocolate →1 S’more You have the following supplies in your pantry: 50 graham crackers, 80 marshmallows, 65 pieces of chocolate. 5. What is limiting reactant? A. The graham crackers B. The marshmallows C. The pieces of chocolate. D. Chocolate and the graham crackers both limit the amount of S’mores 6. How many S’mores can you make? A. 25 B. 21 C. 20 D. 67 7. If you borrowed 10 graham crackers, 20 marshmallows, and 4 pieces of chocolate from your neighbor, and added these to your original amount, how many total S’mores could you make? A. 30 B. 25 C. 23 D. 78

Gravimetric Stoichiometry Use the following information to answer questions # 5-7: The Chemistry recipe for S’mores is : 2 graham crackers + 4 marshmallows + 3 pieces of chocolate →1 S’more You have the following supplies in your pantry: 50 graham crackers, 80 marshmallows, 65 pieces of chocolate. 5. What is limiting reactant? A. The graham crackers B. The marshmallows C. The pieces of chocolate. D. Chocolate and the graham crackers both limit the amount of S’mores 6. How many S’mores can you make? A. 25 B. 21 C. 20 D. 67 7. If you borrowed 10 graham crackers, 20 marshmallows, and 4 pieces of chocolate from your neighbor, and added these to your original amount, how many total S’mores could you make? A. 30 B. 25 C. 23 D. 78

Gravimetric Stoichiometry Use the following information to answer questions # 5-7: The Chemistry recipe for S’mores is : 2 graham crackers + 4 marshmallows + 3 pieces of chocolate →1 S’more You have the following supplies in your pantry: 50 graham crackers, 80 marshmallows, 65 pieces of chocolate. 5. What is limiting reactant? A. The graham crackers B. The marshmallows C. The pieces of chocolate. D. Chocolate and the graham crackers both limit the amount of S’mores 6. How many S’mores can you make? A. 25 B. 21 C. 20 D. 67 7. If you borrowed 10 graham crackers, 20 marshmallows, and 4 pieces of chocolate from your neighbor, and added these to your original amount, how many total S’mores could you make? A. 30 B. 25 C. 23 D. 78

Gravimetric Stoichiometry Use the following information to answer questions # 5-7: The Chemistry recipe for S’mores is : 2 graham crackers + 4 marshmallows + 3 pieces of chocolate →1 S’more You have the following supplies in your pantry: 50 graham crackers, 80 marshmallows, 65 pieces of chocolate. 5. What is limiting reactant? A. The graham crackers B. The marshmallows C. The pieces of chocolate. D. Chocolate and the graham crackers both limit the amount of S’mores 6. How many S’mores can you make? A. 25 B. 21 C. 20 D. 67 7. If you borrowed 10 graham crackers, 20 marshmallows, and 4 pieces of chocolate from your neighbor, and added these to your original amount, how many total S’mores could you make? A. 30 B. 25 C. 23 D. 78 *questions from http://k-12.pisd.edu/schools/pshs/science/Chem/LR_Study_Guide.pdf

Resources For those who need extra help with this subject please see these links or resources. http://k-12.pisd.edu/schools/pshs/science/Chem/LR_Study_Guide.pdf http://www.cdli.ca/courses/chem2202/unit01_org02_ilo03/b_activity.html Chemistry Alberta 20-30 Pages 286 - 293

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