1) An object weighs 75.7 kg. What is this weight in lbs? [1 lb = grams]

Transcription

1 CHEMISTRY 51 SPRING 2016 NAME: Exam 1 Multiple Choice (2 pts each) 1) An object weighs 75.7 kg. What is this weight in lbs? [1 lb = grams] a) 34.3 pounds b) 167 pounds c) 343 pounds d) 16.7 pounds 2) The heat of vaporization for water is 540 cal/g. How many kilocalories are needed to change 22 g of liquid water to steam at 100 C? a) 1.8 kcal b) 25 kcal c) 12 kcal d) kcal 3) A can of vegetable noodle soup is an example of a) an element b) a compound c) a homogeneous mixture d) a heterogeneous mixture 4) Alloys such as bronze, brass or steel are examples of which of the following? a) compounds b) heterogeneous mixtures c) homogeneous mixtures d) Elements 5) Material A has a larger specific heat than material B. Which of the following statements is true about materials A and B? a) A heats faster, but cools slower than B b) A heats and cools faster than B c) A heats slower, but cools faster than B d) A heats and cools slower than B 6) Which of the following is a scientific observation? a) Water freezes at 0 ºC b) When a substance freezes, its molecules lose potential energy c) Freezing and boiling are called physical changes d) If a substance freezes at 0 ºC, it must be water 1

2 7) In a laboratory class with 24 students, 54% of the students are male and 31% of the male students wear blue lab coats. How many students in the laboratory are male students wearing blue lab coats? a) 7 b) 10 c) 13 d) 4 8) Which of the following is a physical change? a) a piece of sulfur is burned b) steam condenses c) a potato rots d) a nail rusts 9) Convert 176 mm to inches (1 in = 2.54 cm). a) 6.93 in b) 69.3 in c) in d) 44.7 in 10) Which of the following is a chemical change? a) Rocks are ground to sand b) Ice melts c) A penny tarnishes d) Water evaporates 11) Which of the following possesses mainly potential energy? a) a stretched rubber band b) a book sitting on a shelf c) a gallon of gasoline d) All of the above 12) The amount of energy required to heat 2.00 g of carbon from 50.0 C to 80.0 C is 42.6 J. of carbon is The specific heat a) J/g C b) J/g C c) 1.42 J/g C d) 2556 J/g C 2

3 13) An empty graduated cylinder weighs g. When filled with 50.0 ml of a liquid it weighs g. The density of the liquid is a) 1.95 g/ml b) g/ml c) 1.10 g/ml d) g/ml 14) Which of the following statements is NOT true of a compound? a) a compound is a pure substance b) a compound has fixed composition c) a compound has properties similar to its components d) all of the above are true 15) Which state of matter retains its volume but adapts its shape to that of its container? a) gas b) liquid c) solid d) none of these 16) A sandy beach stays warm into the evening after a sunny day primarily because a) sand has a small specific heat. b) sand reflects sunlight so well. c) sand has a large specific heat. d) sand absorbs sunlight so well. 17) The measurement m rounded to four significant figures is a) b) c) d) ) Which of the following statements is true of a mixture? a) some mixtures can be separated by simple physical techniques b) a mixture has variable properties c) a mixture does not have fixed composition d) all of the above 3

4 19) The boiling point of octane is 126 o C. What is this temperature on the Fahrenheit scale? a) 102 o F b) 284 o F c) 259 o F d) 52.2 o F 20) Express 549,000,000 in scientific notation. a) 5.49 x 10 8 b) 5.49 x 10 8 c) 54.9 x 10 7 d) 549 x ) Which of the following is a chemical property of chlorine? a) It boils at 34.6 C b) It is a yellowish-green gas c) It has a sharp, suffocating odor d) It combines with sodium to form sodium chloride 22) 5.18 cm 3 of a metal has a mass of g. What is the density of the metal? a) 1.93 g/cm 3 b) 19.3 g/cm 3 c) 5 g/cm 3 d) g/cm 3 23) The boiling point of liquid nitrogen is 77K. What is this temperature on the Celsius scale? a) 25 o C b) 350 o C c) 196 o C d) 171 o C 24) How many significant figures are in the quantity cm? a) 4 c) 3 b) 5 d) 2 25) Which of the following is a mixture? a) gold b) air c) hydrogen fluoride gas d) purified water 4

5 26) Which temperature change is smallest? a) 0 ºC to 10 ºC b) 0 ºF to 10 ºF c) 0 K to 10 K d) They are all the same 27) Two objects, A and B have the same volume. The mass of A is 17.0 g and the mass of B is 14.0 g. Which statement below is correct? a) the density of A is greater than the density of B b) the density of B is greater than the density of A c) the density of A is the same as the density of B d) no conclusive statements about density can be made from the given information 28) Which of the following statements is false? a) Every compound is a substance b) Every compound contains two or more elements c) Every mixture contains two or more substances d) Every substance is a compound 29) The sum ( ), to the correct number of significant figures is a) 25 b) 26 c) d) ) How many mm are in 251 cm? a) 2.51 x 10 2 mm b) 2.51 x 10 3 mm c) 2.51 d) 2.51 x 10 2 mm 31) The area of Asia is approximately 16.8 million square miles. Which of the following is the correct way to express this number in scientific notation? a) b) c) d) 1.68 x

6 32) In which step of the scientific method does the scientist test their hypothesis? a) theory b) conclusion c) observation d) experiment 33) A potato contains 20 g of carbohydrate. How many Calories are obtained from the carbohydrate in the potato? a) 40 Calories b) 20 Calories c) 80 Calories d) 60 Calories 34) Iron has a density of g/cm 3. What is the volume of a block of iron which has a mass of g? a) cm 3 b) cm 3 c) cm 3 d) cm 3 35) Which of the following is true of ice, water and steam? a) they are three different chemical substances b) they are the same substance in different chemical states c) they are the same substance in different chemical and physical states d) they are the same substance in different physical states 36) Which of the following is NOT a chemical change? a) lighting a match b) baking a cake c) boiling water d) burning paper 6

7 37) What is the correct value for the measurement shown below? a) 90.3 ml b) 92.7 ml c) ml d) 93 ml 38) How many milligrams (mg) are there is 1 kilogram (kg)? a) b) c) d) ) The state of matter that has no definite volume or shape is a) elemental b) gas c) liquid d) Solid 40) A serving of fish contains 50 g protein and 4 g of fat. How many Calories are in the serving? (Calculate answer to 2 significant figures) a) 470 Calories b) 220 Calories c) 240 Calories d) 490 Calories 7

8 Problems (20 Points) Where appropriate, show all calculations with units and the correct number of significant figures for full credit. 41. (2 pts.) Shown below is a heating curve for an unknown substance. Use this diagram to answer the questions below: A B Heat added a) What is the boiling point of this substance? b) What phase changes(s) occur between points A and B? 42. (3 pts.) Use the diagrams below to answer the following questions: a) Which diagram(s) represent a sample of an element?_ b) Which diagram(s) represents a sample of a pure compound? c) Which diagram(s) represents a sample of a mixture?_ 8

9 43. (2 pts.) Give the correct element name or symbol for the following: a) Na b) Silicon 44. (4 pts.) The specific heat capacity of aluminum is J/g C. Calculate the amount of energy (in kj) that is needed to warm g of aluminum from 73.0 C to C. 45. (4 pts.) A certain infant medicine has a single dose of 11.4 mg/kg of body weight. How many mg of medicine must be administered in a single dose for a 23 lb infant? (1 lb = 454 g) 46. (5 pts.) Equal amounts of iron, water and sand, all at the same temperature, were placed in an oven and heated briefly. Use the data below to determine which final temperature belongs to each material. Give a brief explanation for your choices. 31 C Specific Heat 5 C _ Water 1.00 cal/g C 46 C Sand 0.16 cal/g C Iron 0.11 cal/g C 9