gravimetric stoichiometry

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

nAl = m/M = 6.49g/26.98g/mol = 0.2405485 mol

nO2 = nAl x mole ratio

Stoichiometry

nAl = m/M = 6.49g/26.98g/mol = 0.2405485 mol

nO2 = nAl x mole ratio 0.2405485 mol Al x 3 mol O2

4 mol Al 0.1804114 mol O2

0.180 mol O2

*example from http://www.cdli.ca/courses/chem2202/unit01_org02_ilo03/b_activity.html

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

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

mAl2O3 = n x M = 0.1202666 mol x 101.96 g/mol =12.262389g =12.26g of Al2O3

*example from http://www.cdli.ca/courses/chem2202/unit01_org02_ilo03/b_activity.html

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

3) What mass of aluminum oxide can be produced from the complete reaction of 0.482 mol of oxygen gas? 4Al(s) + 3O(g) = 2Al3O2

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) = H2(g) + ZnCl2(aq)

A ) 0.0601 mol B ) 3.93 mol C ) 16.6 mol D ) 257 mol

A ) 13.8 g B ) 32.8 g C ) 49.1 g D ) 73.7 g

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’moreYou have the following supplies in your pantry: 50 graham crackers, 80 marshmallows, 65 pieces ofchocolate.5. What is limiting reactant?A. The graham crackersB. The marshmallowsC. The pieces of chocolate.D. Chocolate and the graham crackers both limit the amount of S’mores6. How many S’mores can you make?A. 25B. 21C. 20D. 677. If you borrowed 10 graham crackers, 20 marshmallows, and 4 pieces of chocolate from yourneighbor, and added these to your original amount, how many total S’mores could you make?A. 30B. 25C. 23D. 78

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’moreYou have the following supplies in your pantry: 50 graham crackers, 80 marshmallows, 65 pieces ofchocolate.5. What is limiting reactant?A. The graham crackersB. The marshmallowsC. The pieces of chocolate.D. Chocolate and the graham crackers both limit the amount of S’mores6. How many S’mores can you make?A. 25B. 21C. 20D. 677. If you borrowed 10 graham crackers, 20 marshmallows, and 4 pieces of chocolate from yourneighbor, and added these to your original amount, how many total S’mores could you make?A. 30B. 25C. 23D. 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

gravimetric stoichiometry

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