Final Study Guide

15. The radii of the ions in this series decreases because a. the elements are in the same period b. the effective nuclear charge is increasing c. the atomic radius of Na decreases from Na to Al d. the first ionization energies increase from Na to Al 16. The number of atoms in 9.0 g of aluminum is the same as the number of atoms in a. 8.1 g of Mg b. 9.0 g of Mg c. 12.1 g of Mg d. 18.0 g of Mg 17. A typical silicon chip, such as those in electronic calculators, has a mass of 2.3 x 10-4 g. Assuming the chip is pure silicon, how many silicon atoms are in the chip? a. 4.9 c 10 18 b. 1.4 x 10 20 c. 3.9 x 10 21 d. 2.6 x 10 27 18. Which compound has the highest percent composition by mass of oxygen? a. CaCO 3 b. CaSO 3 c. Li 2 CO 3 d. Li 2 SO 3 19. What is the empirical formula of a compound of carbon, hydrogen, and oxygen, that contains 51.56% carbon and 14.09% hydrogen by mass? a. C 2 H 2 O b. C 6 H 12 O 2 c. C 7 H 2 O 5 d. C 8 H 13 O 2 20. What mass of oxygen, in grams, does 25.5 g of aluminum carbonate, Al 2 (CO 3 ) 3 , contain? Molar mass = 233.99 g/mol. a. 1.59 g b. 1.74 g c. 5.23 g d. 15.7 g 21. The combustion of C 3 H 8 O with O 2 is represented by this equation: 2C 3 H 8 O + 9O 2  6CO 2 + 8 H 2 O When 3.00 g C 3 H 8 O and 7.38 g O 2 are combined, what is the excess reagent and how many moles of that reagent remain? a. 0.006 mol O 2 b. 0.24 mol O 2 c. 0.024 mol C 3 H 8 O d. 0.18 mol C 3 H 8 O 22. Equimolar amounts of nitrogen, hydrogen, and argon are placed in a reaction chamber. The amount of which substance(s) will determine the amount of ammonia produced in the reaction below if the reaction goes to completion? N 2 (g) + 3 H 2 (g)  2NH 3 (g) a. argon b. hydrogen c. nitrogen d. nitrogen and hydrogen

35. a. 1.76 kJ b. 2.52 kJ c. 5.04 kJ d. 13.4 kJ 36. What is the correct Lewis structure for PF 3 ? 37. What is the molecular geometry around the N atom in the molecule depicted? a. t-shaped b. tetrahedral c. trigonal planar d. trigonal pyramidal 38. According to VSEPR, what are the approximate values of the bond angles X and Y? a. X is 90 and Y is 180 b. X is 90 and Y is 120 c. X is 109.5 and Y is 180 d. X is 109.5 and Y is 120