Ch. 6, 9 & 11 light, mole, & stoichiometry [50 points] Chemistry
For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.
Academic Honesty: The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus. I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam. If you violate any of the preceding items or do not sign, your semester grade is a F.
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1. find the average atomic mass based on the following (hypothetical) data. [15 points]

atomic mass (amu) 
% abundance 
^{45 }Ca 
44.983 
3.00 
^{40 }Ca 
39.971 
87.00 
^{38 }Ca 
37.897 
? 
2. mass – mole conversion problems. [10 points]
a. 10.0 g Na_{3 }PO4 = ___ moles of Na_{3 }PO_{4 }b. 2.5 millimoles K_{2 }CO_{3 } = ___ grams of K_{2 }CO_{3 }
3. light [10 points]
a. if frequency = 2.6 * 10 ^{15 } Hz, the energy = ___.b. if wavelength = 217 nm, then energy = __.
4. How many grams of aluminum would be needed to produce 100. mL of water in the following reaction ? [15 points; assume there is excess NH_{4 }ClO_{4 }]
Al + NH_{4 }ClO_{4 } > Al_{2 }O_{3 } + AlCl_{3 } + NO + H_{2 }O