e. As a transition metal, cannot be determined from the information given

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1 hemistry 121 Exam 2 Practice Winter 2018 The following practice examination contains 31 questions. Tuesday s exam will contain 32 questions valued at 3.5 points/question and some rather tasty opportunities for bonus points Name KEY 1. Which of the following contains no covalent bonds? a. 2 S b. 2 SO 4 c. Na 2 S d. Na 2 SO 4 e. (a) & (c) 2. Which of the following contains both an ionic and a covalent bond? a. 2 S b. 2 SO 4 c. Na 2 S d. Na 2 SO 4 e. (b) & (d) 3. What is the formula of the compound that forms when elemental copper reacts with elemental sulfur? a. u 2 S b. us c. u 2 S 3 d. us 2 e. As a transition metal, cannot be determined from the information given 4. What is the formula of the compound that forms when elemental magnesium reacts with elemental nitrogen? Answer: Mg 3 N 2

2 Bonus (3.5 E): Draw the Lewis structure for [the stable form of] elemental nitrogen and then write the balanced chemical equation for the reaction magnesium and nitrogen. :N N: 3Mg + N 2 Mg 3 N 2 As mentioned very early in the quarter, metals exist as very large collections of metal atoms bonded together. As such we just write the symbol for one Mg. We know nitrogen exists as a diatomic elemental species so we write N 2. It is just a matter of ensuring we have the same number of atomic tinker toys we finish with as we started with 5. What is the charge on the barium ion? a. +2 b. +1 c. 0 d. -1 e What is the charge on dihydrogen sulfide? a. +2 b. +1 c. 0 d. -1 e. -2 Nonpolar covalent molecule 7. The mineral portion of bone is primarily hydroxyapatite, a 10 (PO 4 ) 6 (O) 2. Name each ion in hydroxyapatite, give it s charge and show the formula represents a neutral compound Ion Name harge on Ion Total harge for Ion alcium Phosphate ydroxide -1-2 Summing total charge: (+20) + (-18) + (-2) = 0 harge neutrality count on it

3 Please name the following compounds 8. si 1 cesium iodide 9. Sr 2 strontium chloride 10. BaSO 4 barium sulfate 11. u(o) 2 copper(ii) hydroxide 12. uo copper(ii) oxide Please provide the formula for the following compounds 13. alcium bromide abr Lithium carbonate Li 2 O Ammonium nitrate N 4 NO Dinitrogen tetrahydride N 2 4 Bonus: On questions drawing an additional isomer with earn 1.75 extra credit points but every incorrect or repeated molecule will cost you 1.75 extra credit points limit 2 additional isomers 17. Draw an acceptable Lewis structure for Show appropriate geometry and include non-bonded pairs of electrons if applicable. Many other possibilities exist. Make certain you include non-bonded pairs of electrons 1 Anyone who writes rime Scene Investigation or puts Miami in the blank will perish

4 18. Draw an acceptable Lewis structure for Show appropriate geometry and include non-bonded pairs of electrons if applicable. 19. Draw an acceptable Lewis structure for 3 7 NO. Show appropriate geometry and include non-bonded pairs of electrons if applicable. 20. Which of the following molecules is the most polar? a b c O d S e. All have approximately the same polarity Oxygen has the 2 nd highest electronegativity value of the elements (fluorine is top dog) 21. Which of the following would you expect to have the greatest solubility in water? a b c O d S e. All have approximately the same water solubility

22. ow many moles are contained in 64.0 g of methane, 4? a. 2.50 x 10-1 mol b. 7.50 x 10-1 mol c. 1.33 x 10 0 mol d. 4.00 x 10 0 mol 64.0 g(mol/16.0 g) 23.

5 22. ow many moles are contained in 64.0 g of methane, 4? a x 10-1 mol b x 10-1 mol c x 10 0 mol d x 10 0 mol 64.0 g(mol/16.0 g) 23. Please provide balanced chemical equations for the combustion of methane, 4, and the combustion of propane, O 2 O O O 2 3O O 24. Please balance the following acid-base reaction. 2NO 3 + 1Ba(O) 2 1Ba(NO 3 ) O Look at as a swap nitrate for hydroxide or Ba +2 for + and you will be fine 25. Write the net ionic equation when solutions of uso 4 and N 4 are mixed. If there is no reaction, write N.R. Possibilities: (N 4 ) 2 SO 4 or u 2 NR

6 26. Write the net ionic equation when solutions of Na 3 PO 4 and Sr(NO 3 ) 2 are mixed. If there is no reaction, write N.R. Possibilities: NaNO 3 or Sr 3 (PO 4 ) 2 3Sr +2 (aq) + 2PO 4-3 (aq) Sr 3 (PO 4 ) 2 (s) 27. Write the net ionic equation when solutions of FeSO 4 and NaO are mixed. If there is no reaction, write N.R. Possibilities: Na 2 SO 4 or Fe(O) 2 Fe +2 (aq) + 2O - (aq) Fe(O) 2 (s) Fe = transition metal; determine charge via charge on nitrate 28. In the acid-base reaction below, indicate the conjugate base of the acid and the conjugate acid of the base by drawing a line between them and labeling. Label both members of each pair. Base A. NaO + 2 O 3 NaO O Acid B. The stronger the acid or base, the weaker its conjugate. Much more on this later 29. Please give the products of the following acid-base reaction. If there is no reaction write NR 2 SO 4 + 2NaO Na 2 SO O strong acid + strong base Water as a [conjugate acid] product only with hydroxide as base 30. Please give the products of the following acid-base reaction. If there is no reaction write NR 2 SO 4 + 2N 3 (N 4 ) 2 SO 4 strong acid + weak base No hydroxide as base, no water as product; neutral ammonia becomes ammonium cation 31. Please give the products of the following acid-base reaction. If there is no reaction write NR 2 SO O 3 NR 2 acids, no base to accept +

The following practice examination contains 32 questions. Thursday s examination will contain 32 questions valued at 3.

Chemistry 121 Exam 2 Practice Spring 2018 The following practice examination contains 32 questions. Thursday s examination will contain 32 questions valued at 3.5 points/question Name KEY 1. Which of the