1 Chemistry Foundations

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1 Aubrey High School PreAP -Chemistry 1 Chemistry Foundations Name Period Date / / 1.2 Problems - Density You may use a pencil, eraser, and scientific calculator to complete the test. No other resources are allowed. You have fifty (50) minutes to complete this test, unless other arrangements have been made. Unless otherwise specified, please provide explanations in complete sentences. For calculation questions, please show all work; numerical answers must have the correct number of significant figures and units to receive full credit. SECTION 1: MULTIPLE CHOICE. Select the best answer choice for each question. (1 point each) 1. Which of the following is a correct measurement for the length of the line shown below, using the ruler given? (A) 4 cm (B) 4.5 cm (C) 4.50 cm (D) cm 2. Which of the following is a correct measurement for the volume of water in the graduated cylinder shown to the right? (A) 12 ml (B) 12.1 ml (C) 13 ml (D) 13.1 ml 3. The measurement mg has how many significant figures? (A) 2 (B) 3 (C) 5 (D) 7 4. Which of the following measurement(s) has three significant figures? I II. 320 III. 85,100. (A) I only. (B) II and III only. (C) I and III only. (D) I, II, and III Which of the following expresses the result written with the correct significant figures? 3.26 (0.2900)(1.481) (A) 7.59 (B) (C) 7.6 (D) The following marks on the target represents someone who is: (A) Accurate, but not precise. (B) Precise, but not accurate. (C) Both accurate and precise. (D) Neither accurate nor precise. 7. How close a measurement is to the true value is the of the measurement and is communicated as (A) accuracy, % error (B) accuracy, average deviation (C) precision, % error (D) precision, average deviation 8. When measuring the volume of a metal sphere, the following class results were obtained: Mr. Ku ± 0.5 cm 3 0.7% error Mr. Groves ± 0.2 cm 3 1.0% error Compared to those of Mr. Groves class, the data for Mr. Ku s class are: (A) Less precise and accurate. (B) More accurate, but less precise. (C) More precise and accurate. (D) More precise, but less accurate.

2 9. Which of the following quantity is INCORRECTLY paired with its unit? (A) Length kl (B) Mass dg (C) Time s (D) Volume dm Which of the following relationships is correct? (A) 1 cg = 100 g 1 (B) 1 dm = 100 m (C) 1 km = 100 m (D) 1 ml = L 14. C 2H 5OH (l) C 2H 5OH (g) The chemical equation below best represents (A) A chemical change (B) A chemical property (C) A physical change (D) A physical property 15. All of the following are physical properties EXCEPT: (A) Color (B) Corrosiveness (C) Density (D) Mass 11. Your average body temperature is 37 C. What is this in Kelvin? (A) 237 K (B) 37 K (C) 287 K (D) 310 K 12. When converting 35.2 inches to centimeters, the following fraction is used: (1 in = 2.54 cm) 35.2 in?? 16. Blocks A and B are both made of copper and have masses 1.5 kg and 4.5 kg, respectively. The density of Block A that of Block B. (A) Is greater than (B) Is less than (C) Is the same as (D) Cannot be compared with 17. Consider a 2-L block of zinc (density = 7.12 g/ml) and a 2-L block of silver (density = 10.5 g/ml). Which has a greater mass? (A) 1 in (A) The block of zinc cm (B) The block of silver. (B) 2.54 cm (C) They have the same mass. 1 in (D) It cannot be determined in (C) 1 cm mL samples of olive oil and sea water are 1 cm combined, forming separate layers. The olive oil (D) 2.54 in forms the top layer, and the sea water forms the bottom layer. Which liquid has a greater mass? 13. Which of the following factors is used when (A) Olive oil converting 15,000 cm 2 to m 2? (B) Sea water 1 m 2 (C) They have the same mass. (A) 2 (D) It cannot be determined. 100 m 2 (B) 1 cm The density of limestone is 2.7 g/cm 3. Which of 1 m the following expressions gives the volume of a (C) 1 m 32.0 g chunk of limestone? 1 m 1 m 2.7 (D) (A) (B) 2.7 (C) (32.0)(2.7) (D)

3 SECTION 2: FREE RESPONSE. Show all your work to receive full credit. 20. A Material Safety Data Sheet (MSDS) provides physical, chemical, and safety information about a chemical. The following is an excerpt for the MSDS for 30% hydrogen peroxide, H 2O 2. MATERIAL SAFETY DATA SHEET (MSDS) Section 1 Chemical Product and Company Identification Hydrogen Peroxide (30%) Section 2 Composition, Information, on Ingredients Hydrogen peroxide Synonyms: hydrogen dioxide Section 3 Hazards Identification Clear, colorless liquid. Slightly acrid odor. Harmful by ingestion, inhalation, or skin contact. Corrosive and severe irritant to skin, eyes, and respiratory tract. Causes severe burns. Avoid all body contact. Contact with eyes may cause blindness. 30% hydrogen peroxide will decompose rapidly when exposed to almost any substance and generate significant heat. Section 5 Fire Fighting Measures Noncombustible liquid, but a powerful oxidizer. Strong oxidizing agent; dangerous fire and explosion risk when in contact with combustible materials. Fire Fighting Instructions: Use a triclass, dry chemical fire extinguisher. Firefighters should wear PPE and SCBA with full facepiece operated in positive pressure mode. Section 9 Physical and Chemical Properties Clear, colorless, liquid with a slightly acrid odor. Solubility: Soluble in water and alcohol. Formula: H2O2 Formula weight: Boiling point: 106 C Melting point: -25 C ph (30%): 3.3 Specific gravity: Vapor density: 1.17 Section 10 Stability and Reactivity Keep away from reducing agents, strong bases, organics, combustible material, and oxidizable materials. Avoid heating this substance. Shelf life: Fair to poor. Stored at room temperature, this substance decomposes at about 0.5% per year. Section 11 Toxicological Information Acute effects: Corrosive to all body tissues. Chronic effects: Dermatitis. Target organs: N.A. (a) State two physical properties of H 2O 2. (b) State two chemical properties of H 2O 2. (c) State two safety procedures you should follow when handling H 2O 2. (It could be a procedure while working with the chemical, or if there is a spill that takes place.)

4 21. The reaction in the Elephant s Toothpaste demonstration (H 2O 2 with KI) was carried out, without the food coloring or dish soap. The following data was obtained: Volume of 30% H 2O 2 used: ml Room Pressure: kpa Initial Temperature: 29.2 C Final Temperature: C (a) The volume of the sample of H 2O 2 was reported as ml. What would be the volume markings on the graduated cylinder for the lines indicated? (2 points) (b) The density of the H 2O 2 solution is g/ml. What is the mass of this ml H 2O 2 solution? (4 points) I E S A (c) What is the temperature change in this experiment in kelvin? (Show your calculations and/or provide an explanation.) (4 points) (d) The room pressure was kpa. If 1 atm = kpa and 1 atm = 760 torr, what is the room pressure in torr? (Assume numbers in conversion factors are exact.) (Show your work using dimensional analysis.) (4 points) 22. Groups in Mr. Ku and Mr. Groves s classes determined the density of the H 2O 2 solution. Their results are shown below. Mr. Ku s Class Mr. Groves s Class Density (g/cm 3 ) Deviation Density (g/cm 3 ) Deviation Average: Average:

5 (a) Calculate the average and average deviation for the data from each class. Report the class data in ± notation. (Fill in the chart above. Work for the calculations does not need to be shown.) Mr. Ku s Class: ± g/ml Mr. Groves s Class: ± g/ml (b) Calculate the % error for the average of each class if the accepted value of the density of the H 2O 2 solution is g/ml. (Work for the calculations does not need to be shown.) Mr. Ku s Class: % Mr. Groves s Class: % (c) Which class is more accurate? Why? (Use complete sentences) (d) Which class is more precise? Why? (Use complete sentences) (e) If 20.0 g blocks of ice (H 2O) were placed in 500-mL samples of acetone and H 2O 2, would they sink or float? (Density of ice: 0.92 g/cm 3 ; density of acetone: 0.79 g/ml; density of H 2O 2: 1.45 g/ml) The 20.0-g block of ice would in 500-mL acetone solution because: The 20.0-g block of ice would in 500-mL H 2O 2 solution because: