Chemistry 121 Fall 2000 Oregon State University Exam 1 October 19

Chemistry 121
Fall 2000
Oregon State University
Exam 1
October 19, 2000
Dr. Richard Nafshun
Dr. Carroll DeKock

DO NOT OPEN THIS EXAM UNTIL INSTRUCTED.

CALCULATORS ARE NOT TO BE SHARED.

Instructions: You should have with you several number two pencils, an eraser, your 3" x 5" notecard, and your University ID Card. You may use a TI-25X Solar calculator if you wish. If you have notes with you, place them in a sealed backpack and place the backpack OUT OF SIGHT. Or place the notes directly on the table at the front of the room.

Fill in the front page of the Scantron answer sheet with your last name, first name, middle initial, and student identification number. Leave the class section number and the test form number blank.

This exam consists of 18 multiple-choice questions and 7 open-ended questions. Each multiple-choice question has four points associated with it. Select the best answer by filling in the corresponding circle on the rear page of the answer sheet. If you have any questions before the exam, please ask. If you have any questions during the exam, please raise your hand to attract the attention of a proctor. The proctor will come to you. Open and start this exam when instructed. Present your ID card when submitting the exam. Place your open-ended portion of this exam in the appropriate stack. Place your 3" x 5" notecard in the appropriate stack. You may keep the multi-choice portion of this exam, so please mark the answers you selected on it.

1. Which of the following is an ionic compound?

(A) Water.

(B) Tetraphosphorus trisulfide.

(D) Sulfate.

(E) Lithium chloride.

2. The mass of a sodium chloride crystal is measured to be 0.03450 kg. Expressed in grams:

(A) 0.00003450 g.

(B) 0.0003450 g.

(D) 34.50 g.

(E) 345.0 g.

3. A student obtains a sample of silver. She measures the volume of the sample to be 34.75 in³.

(1 in = 2.54 cm). Expressed in cm³, the volume of the sample is:

(A) 2.121 cm³.

(B) 13.68 cm³.

(D) 224.2 cm³.

(E) 569.5 cm³.

4. A student measures the mass of a zinc sample to be 0.0040 g.

(A) There are two significant figures in this measured quantity.

(B) There are three significant figures in this measured quantity.

(D) There are five significant figures in this measured quantity.

(E) This measured quantity is ambiguous. It is not clear how many significant figures are in this measured quantity.

5. Consider the following operation: 3.1017 g + 29.23 g. The correct answer with the proper number of significant figures is:

(A) 32. g.

(B) 32.3 g.

(D) 32.332 g.

(E) 32.3317 g.

6. ⁴⁰Ca²⁺ has:

(A) 2 electrons.

(B) 18 electrons.

(D) 22 electrons.

(E) 40 electrons.

7. ¹⁶O has:

(A) 2 neutrons.

(B) 6 neutrons.

(D) 14 neutrons.

(E) 16 neutrons.

8. ⁷Li has:

(A) 1 proton.

(B) 3 protons.

(D) 6.941 protons.

(E) 7 protons.

9. Which of the following sets of elements are expected to have similar properties?

(A) Calcium and potassium.

(B) Calcium and magnesium.

(D) Calcium and bromine.

(E) Calcium and selenium.

10. The chemical formula of magnesium nitrate is:

(A) Mg₂N.

(B) Mg₃N₂.

(D) Mg₂NO₃.

(E) Mg(NO₃)₂.

11. The chemical formula of calcium carbonate is:

(A) Ca₂C.

(B) CaC₂.

(D) Ca₃CO₂.

(E) CaCO₃.

12. Which of the following sets of elements will form a molecular compound?

(A) Na and Mg.

(B) Na and F.

(D) He and Na.

(E) C and Cl.

13. When combined with fluorine, a Group 1 element will tend to:

(A) Gain one electron.

(B) Gain two electrons.

(D) Lose two electrons.

14. CH₃OCH₃ is:

(A) an alkane.

(B) an alkene.

(D) an alcohol.

(E) an ether.

15. Which of the following is hexene?

(A) CH₃CH₂CH₂CH₂CH₂CH₃.

(B) CH₃CH=CHCH₂CH₂CH₃.

(D) CH₃CH₃CH₃CH₃CH₃CH₃.

(E) CH₂CH₂CH₂CH₂CH₂CH₂.

16. Which of the following is a base?

(A) Na₂SO₄.

(B) CH₃CH₃.

(D) HCl.

(E) CH₃COOH.

17. A student obtains a 20.823 gram sample of lithium metal. There are:

(A) 3.000 moles of lithium present.

(B) 6.941 moles of lithium present.

(D) 62.469 moles of lithium present.

(E) 1.81 x 10²⁴ moles of lithium present.

18. The formula mass (AKA molar mass) of lithium sulfate is:

(A) 3.00 g/mol.

(B) 39.00 g/mol.

(D) 71.06 g/mol.

(E) 109.94 g/mol.

Chemistry 121 Fall 2000 Oregon State University

Exam 1 October 19, 2000

Student's Name __________________________________________

ID Number __________________________________________

Lecture Instructor (Circle One)          Dr. Richard Nafshun            Dr. Carroll DeKock
Recitation Day (Circle One)                                M/W                                      T/R
Recitation Time (Circle One)                              0800        0900        1000        1100        1200        1300        1400        1500

YOU MUST SHOW ALL WORK ON NUMERICAL PROBLEMS TO RECEIVE CREDIT

1. [3 points] Convert 46.8 ounces to kg. [16 ounces = 1 lb by definition and 1 lb = 453.59 g]

2. [3 points] Discuss why NaCl(common table salt) is said to be a pure substance while wine (or beer)

is said to be a homogeneous mixture.

3. [4 points] Circle the compounds in the following list of five which are ionic.

CO₂ H₂S K₂CO₃ Na₃PO₄ PF₅

4. [4 points] Write correct formulas for:

(a) aluminum fluoride ___________________________________

(b) sodium oxide ___________________________________

(d) tetraphosphorous hexoxide ___________________________________

5. [4 points] Draw the isomers for the alcohol C₃H₇OH.

6. [6 points] (a) Calculate the molecular mass (formula mass) of C₅H₁₂.

Answer:

(b) Calculate the number of moles of C₅H₁₂ in 175.0 kg of C₅H₁₂.

Answer:

7. [4 points] Each of the compounds below belongs to one of the following classes of substance: alkane, alkene, alkyne, ether, and carboxylic acid. Write the name of each class adjacent to the formula of the compound.

(a) CH₃CH₂CH₂OCH₃

(b) CH₃CH₂COOH

(d) C₅H₁₂