College Chemistry Midterm

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13. (4 pts) The density of liquid acetone, (CH3)2CO (FM =58.08), is 0.790 g/mL at 68 degrees F. What

is this same temperature in K, and how many acetone molecules will occupy a cubic container, 1 mm on

each side?

14. (3 pts) Copper has two naturally occurring forms, 63Cu and 65Cu. The average atomic mass of Cu is

63.546 amu. If the mass of 63Cu is 62.930 amu, and the mass of 65Cu is 64.928 amu, what is the percent

abundance of 65Cu?

% abundance of 65Cu = ___________________

26Na+

16. (5 pts) Write the balanced net ionic equation using chemical formulas for the reaction between

aqueous solutions of lithium sulfate and lead (II) nitrate. Use the smallest whole number coefficients, and

identify the spectator ions.

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17. (3 pts) What is the mass percent of carbon in carbon tetrachloride (FM = 153.82)?

18. (6 pts) A certain compound contains only C and H and has a molar mass of about 86 g/mol. A

sample of the compound burns in a combustion apparatus yielding 26.4 g CO2 and 12.6 g H2O. What is

its molecular formula?

19. (5 pts) A sample of a compound containing carbon and hydrogen contains 22.2 g carbon and 3.7 g

hydrogen. How many grams of carbon are in a 50 g sample of this compound?

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21. (6 pts) What is the theoretical yield of CaSO4 (in g) if 3.00 g CaF2 (FM = 78.08) react with 3.60 g

H2SO4 (FM = 98.09)? What is the percent yield if 1.97 g of CaSO4 (FM = 136.14) are actually obtained?

22. (a) (2 pts) What volume (in mL) of 1.67 M LiOH (FM = 23.95) is required to make 100.0 mL of

0.500 M LiOH?

23. If 15.0 mL of aqueous acetic acid solution is neutralized by (i.e., completely reacted with) 13.3 mL of

0.049 M barium hydroxide, what is the molar concentration of acetic acid in solution?

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Convert 430 nm to frequency (Hz).

25. (4 pts) Calculate the wavelength of a photon emitted when hydrogen atoms relax from the n = 5

state to n = 2.

(0, 1, -1, 1/2)

(2, 2, -1, -1/2)

27. The ionization energy of P is larger than that of Ga. Explain why. (Merely pointing out their location

on the periodic table will not suffice – you should discuss effective charge in your answer.

28. (3 pts) Sketch the energy level diagram of the C atom in its ground state. Are C atoms paramagnetic

or diamagnetic? Briefly explain.