Practice Exam 1 100 points
Chapters 1 - 4
75 minute Exam
Multiple Choice: (2 pts each) Carefully read and deduce or calculate (as needed) the best answer. Indicate your choice in the blank provided. There is only one correct answer unless stated otherwise.
_____1. Which of the following is a set of isotopes?
E) all sets are isotopes
F) none of the sets are isotopes
_____2. The molar mass of Ni3(PO4)2 is (g/mol):
A) 105.66 B) 153.66 C) 271.04
D) 302.01 E) 303.04 F) 334.01
G) 335.04 H) 366.01
_____3. Which of the following has three significant figures? State all that apply.
A) 0.67 B) 0.0300 C) 0.004
D) 2.54 cm/in E) 270 F) all have 3 sig figs
_____4. These three equations describe an oxidation-reduction method for determining dissolved oxygen in water. How many moles of S2O32¯ are equivalent of each mole of O2?
1) 2Mn2+(aq) + 4OH¯(aq) + O2(g) ---> 2MnO2(s) + 2H2O(l)
2) MnO2(s) + 2I¯(aq) + 4H+(aq) ---> Mn2+(aq) + I2(aq) + 2H2O(l)
3) 2S2O32¯(aq) + I2(aq) ---> S4O62¯(aq) + 2I¯(aq)
A) 4 mol B) 2 mol C) 1 mol D) 0.5 mol
_____5. A dilute HCl solution is to be prepared from a more concentrated solution. Which of pieces of glassware will give the highest level of precision?
A) pipet and graduated cylinder
B) two graduated cylinders
C) pipet and volumetric flask
D) graduated cylinder and volumetric flask
_____6. Calculate the percent by mass of hydrogen in diethylamine, (C2H5)2NH.
______7. Given an HNO3 sample containing 6.02 x 1023 atoms of O. How many moles of HNO3 are in the sample?
A) 0.20 moles B) 0.33 moles C)1mole D)3 moles E) 5 moles
F) not enough information to determine
_____8. Given the reaction: 6 Li (s) + N2 (g) > 2 Li3N (s)
Given that 0.50 moles of Li3N (s) are produced, how many moles of Li (s) would be needed? Assume excess nitrogen.
A) 0.33 mols B) 0.67 mols C) 0.50 mols D) 1.0 mols
E) 1.5 mols F) 4.0 mols G) 6.0 mols H) 12 mols
_____9. Calculate the density of a gold coin from the given data.
Table of Data
Mass of the gold coin 13.5243 g
Volume of the coin and water 22.90 mL
Volume of the water alone 22.20 mL
A) 19.32 g/mL
B) 19.3 g/mL
C) 19 g/mL
D) 2 x 101 g/mL
_____10. Which of the following has a molecular formula that is also the empirical formula?
A) Na2C2O4 B) P2O10 C) C4H10 D) Hg2(NO3)2 E) C2H4O
F) none of these
_____11. Each of three samples was weighed on a different balance. The masses of the three are 1.028 kg, 82.9 g, and 45.1 mg. The sum of the three masses should be reported as
A) 1.11 x 103 g B) 1110.9451 g C) 1111 g D) 110 g
_____12. Which pair of substances could be used to illustrate the law of multiple proportions?
A) SO3 and H2SO4
B) CO and CO2
C) Fe2+ and Fe3+
D) CH2O and C6H12O6
E) Chlorine-35 and chlorine-37
13.(4 pts) Calculate and report the final answer to the correct number of significant figures.
A) 27.2 + 1.80 = ____________ B) (6.84 x 105 )/ 4273 = ______________
14. (6 pts) Balance the following redox reaction in acidic conditions.
H2O2 + MnO4- à O2 + Mn2+
For the above reaction ___________ is the element oxidized, and _________________ is the oxidizing agent.
15. (8 pts) A 1.42 g sample of a pure compound, with formula M2SO4, was dissolved in water and treated with an excess of aqueous barium chloride, resulting in the precipitation of all the sulfate ion as barium sulfate. The precipitate was collected, dried, and found to weigh 2.33 g. Determine the atomic mass of M, and identify M.
16. (6 pts) A compound contains only carbon, hydrogen, nitrogen, and oxygen. Combustion of 0.157 g of the compound produced 0.213 g CO2 and 0.0310 g of H2O. In another experiment, it is found that 0.103 g of the compound produced 0.0230 g of NH3. What is the empirical formula of the compound?
17. (4 pts) When FeCl3 is ignited in an atmosphere of pure oxygen, this reaction takes place.
4 FeCl3(s) + 3 O2(g) à 2 Fe2O3(s) + 6 Cl2(g)
If 3.4 mol of FeCl3 are ignited in the presence of 2.2 mol of O2 gas, how much (in moles) of which reagent is present in excess and therefore remains unreacted?
18. (8 pts) What mass (in grams) of carbon dioxide is collected when 300.0 mL of 0.200 M sodium bicarbonate is added to 200.0 mL of 0.15 M citric acid, H3C6H5O7?
____ NaHCO3 + _1_ H3C6H5O7 > ____ CO2 + ___ H2O + _1_ Na3C6H5O7 (unbalanced)
19. (8 pts) An alloy used in aircraft structures consists of 93.7 % Al and 6.3 % Cu by mass. The alloy has a density of 2.85 g/cm3. A 0.691 cm3 piece of the alloy reacts with excess HCl(aq). If we assume than all of the Al but none of the Cu reacts with hydrochloric acid, what is the mass of H2 obtained? The reaction of Al with the acid is given below:
2 Al (s) + 6 HCl (aq) → 2 AlCl3(aq) + 3H2(g)
Nomenclature and Net Ionic Equations
20. (6 pts) A) Convert the following description into a balanced chemical (molecular) equation:
When solutions of calcium chloride and sodium phosphate are mixed, solid calcium phosphate forms and sodium chloride remains in solution.
B) Draw in the beaker below the ions and compound present after the reaction occurs.
21. (6 pts) 1. Name the following compounds
A. P2O4 ____________________________
B. H2SO3 ____________________________
C. H2S (aq) ____________________________
D. NaBrO3 ____________________________
F. Cu(H2PO4)2 ____________________________
22. (6 pts) Write formulas for the following compounds
A. lead(IV) carbonate ____________
B. dinitrogen pentoxide ____________
C. nitrous acid ____________
D. mercury(I) acetate ____________
E. ammonium dichromate ____________
F. barium hydrogen sulfate ____________
23. (6 pts) For the following reactions, clearly predict the products and balance the molecular equation. Show the complete Net Ionic Equation on the indicated line and show all physical states in parenthesis.
A) ___ FeCl3+ ___ NH3 + ___H2O >
B) _____ Ag3PO4 + _____ HNO3 >
(6) 24. (6 pts) Write balanced net ionic equations for the following reactions. Show all physical states in parenthesis.
A. aqueous copper(II) chloride and aqueous potassium hydroxide
B. aqueous hydrochloric acid and aqueous sodium nitrite
C. aqueous ammonia and hydrofluoric acid