Problem Set I - Chem 1211

Problem Set I - Chem 1211 (Answer Key)

1. Express the results of the following calculations with the correct number of significant figures.

a. (3.41 – 0.23) x 0.205 (Ans. 3 sig fig.) 5.233 b. (5.556 x 2.3) (Ans. 2 sig. fig.) (4.223 – 0.08)

2. The normal body temperature of a goat is 39.9 oC. Express the temperature in oF and K. (Ans. = 103.8 oF, 313.05 K)

3. Sodium chloride has a melting point of 1074 K. Convert this temperature to oC and oF. (Ans. = 801 oC; 1474 oF))

o 4. The density of chloroform, CHCl3, is 1.4832 g/mL at 20 C. What would be the volume of 112.5 grams of chloroform? (Ans. = 75.85 mL)

5. Give the names or the chemical formula of the following compounds: a. PbS (lead(II)sulfide) b. BaCl2 (barium chloride) c. P4O7 (tetraphosphorus heptaoxide) d. HIO4 (aq) ( periodic acid) e. Calcium hypochlorite (Ca(ClO)2) f. Iron(I)carbonate (Fe2(CO3)) g. Dinitrogen triiodide (N2I3) h. Beryllium bromide (BeBr2) i. Sulfurous acid (H2SO3) j. Aluminum oxide (Al2O3) k. Hydrobromic acid (HBr) l. Tin(IV)oxide (SnO2) m. NaBrO3 (sodium bromate)

6. Give the number of protons, electrons and neutrons for 207Pb. (Ans. = 82 p+, 82 e-, 125 n)

7. Give the complete isotope symbol for Gold-197. (Ans. = 197Au)

8. Given 21.5 grams of C3H4O3, calculate the following:

a. molar mass of C3H4O3. (Ans. = 88.065 grams/mole) b. number of moles of C3H4O3.(Ans. = 0.244 mole) c. number of moles of C. (Ans. = 0.732 mole) d. number of moles of H (Ans. = 0.976 mole) e. number of moles of O (Ans. = 0.732 mole) 23 f. number of molecules of C3H4O3. (Ans. = 1.47 x 10 ) g. number of atoms of C. (Ans. = 4.41 x 1023) h. number of atoms of H. (Ans. = 5.88 x 1023) i. % Mass of C in C3H4O3. (Ans. = 40.9%)

9. Determine the empirical formula and the molecular formula for the compound that contains 24.25% F and 75.75% Sn. The molar mass of the compound is 313.42 grams/mole. (Ans. Empirical formula = SnF2; molecular formula = Sn2F4)