Gen. Chemistry Exam #1

Write the following numbers and results in scientific notation, with appropriate significant figures. b. Area, πr2 , where r = 8.7 cm

2.37787148 x 10^2

Write the following numbers and results in scientific notation, with appropriate significant figures. a. 0.000000673

6.73 x 10^-7

An evacuated 276 mL glass bulb weighs 129.6375 g. Filled with an unknown gas, the bulb weighs 130.0318 g. Calculate the gas density in g/L, and express it with an appropriate number of significant figures.

1.43 g/L

Write the following numbers and results in scientific notation, with appropriate significant figures. c. 23.24 + 18.6 - 5

3.684 x 10^1

A flask has a mass of 78.23 g when empty and 593.63 g when filled with water. When the same flask is filled with concentrated sulfuric acid, H2SO4, its mass is 1026.57 g. What is the density of concentrated sulfuric acid? (Assume water has a density of 1.00 g/cm3 at the temperature of the measurement.) A) 1.992 g/cm3 B) 1.840 g/cm3 C) 1.729 g/cm3 D) 1.598 g/cm3 E) 0.543 g/cm3

A) 1.992 g/cm3

A large pizza has a diameter of 15 inches. Express this diameter in centimeters. A) 38 cm B) 24 cm C) 18 cm D) 9.3 cm E) 5.9 cm

A) 38 cm

Bud N. Chemist must determine the density of a mineral sample. His four trials yield densities of 4.77 g/cm3 , 4.67 g/cm3 , 4.69 g/cm3 , and 4.81 g/cm3 . Independent studies found the correct density to be 4.75 g/cm3 . Which of the following statements represents the best analysis of the data? A) Bud's results have much greater accuracy than precision. B) Bud's results have much greater precision than accuracy. C) Bud's results have high accuracy and high precision. D) Bud's results have low accuracy and low precision. E) Bud's equipment is faulty.

A) Bud's results have much greater accuracy than precision.

Select the best statement. A) Physical changes may be reversed by changing the temperature. B) Physical changes alter the composition of the substances involved. C) Physical properties are not valid characteristics for identifying a substance. D) Physical properties are mostly extensive in nature. E) Physical changes are usually accompanied by chemical changes.

A) Physical changes may be reversed by changing the temperature.

Acetone, which is used as a solvent and as a reactant in the manufacture of Plexiglas®, boils at 56.1°C. What is the boiling point in degrees Fahrenheit? A) 159°F B) 133°F C) 101°F D) 69.0°F E) 43.4°F

B) 133°F

Isopropyl alcohol, commonly known as rubbing alcohol, boils at 82.4°C. What is the boiling point in kelvins? A) 387.6 K B) 355.6 K C) 323.6 K D) 190.8 K E) -190.8 K

B) 355.6 K

A student makes several measurements of the density of an unknown mineral sample. She then reports the average value of these measurements. The number of significant figures she uses in her result should be a measure of its A) accuracy. B) precision. C) systematic error. D) determinate error. E) human error.

B) precision.

The distance between carbon atoms in ethylene is 134 picometers. Which of the following expresses that distance in meters? A) 1.34 × 10-13 m B) 1.34 × 10-12 m C) 1.34 × 10-10 m D) 1.34 × 10-7 m E) 1.34 × 10-6 m

C) 1.34 × 10-10 m

Which of the following represents the largest volume? A) 10,000 µL B) 1000 pL C) 100 mL D) 10 nL E) 10 cm3

C) 100 mL

Select the answer that expresses the result of this calculation with the correct number of significant figures and with correct units. 16.18 cm × 9.6114 g ÷ 1.4783 cm2 = A) 105.2 g/cm3 B) 105.2 g/cm2 C) 105.2 g/cm D) 72.13 g/cm2 E) 72.13 g/cm

C) 105.2 g/cm

The mass of a sample is 550 milligrams. Which of the following expresses that mass in kilograms? A) 5.5 × 108 kg B) 5.5 × 105 kg C) 5.5 × 10-4 kg D) 5.5 × 10-6 kg E) 5.5 × 10-1 kg

C) 5.5 × 10-4 kg

Select the best statement. A) Chemical changes provide the only valid basis for identification of a substance. B) Chemical changes are easily reversed by altering the temperature of the system. C) Chemical changes always produce substances different from the starting materials. D) Chemical changes are associated primarily with extensive properties. E) Chemical changes are accompanied by changes in the total mass of the substances involved.

C) Chemical changes always produce substances different from the starting materials.

Select the best statement about chemistry before 1800. A) Alchemy focused on objective experimentation rather than mystical explanations of processes. B) The phlogiston theory laid a valuable theoretical basis for modern chemistry. C) Lavoisier's quantitative work on the role of oxygen in combustion was the beginning of modern chemistry. D) The interpretation of data by alchemists was not biased by their overall view of life. E) Alchemists failed because they did not develop any practical chemical methods.

C) Lavoisier's quantitative work on the role of oxygen in combustion was the beginning of modern chemistry.

Which of the following is a chemical change? A) boiling of water B) melting wax C) broiling a steak on a grill D) condensing water vapor into rainfall E) carving a piece of wood

C) broiling a steak on a grill

As chief chemist at Superior Analytical Products (SAP) you must design an experiment to determine the density of an unknown liquid to three (3) significant figures. The density is of the order of 1 g/cm3 . You have approximately 7 mL of the liquid and only graduated cylinders and balances are available for your use. Which of the following combinations of equipment will allow you to meet but not exceed your goal? A) graduated cylinder with ±0.1 mL uncertainty; balance with ±0.1 g uncertainty B) graduated cylinder with ±0.01 mL uncertainty; balance with ±0.1 g uncertainty C) graduated cylinder with ±0.01 mL uncertainty; balance with ±0.01 g uncertainty D) graduated cylinder with ±0.001 mL uncertainty; balance with ±0.001 g uncertainty E) graduated cylinder with ±0.1 mL uncertainty; balance with ±0.001 g uncertainty

C) graduated cylinder with ±0.01 mL uncertainty; balance with ±0.01 g uncertainty

The symbol for the SI base unit of mass is A) mg. B) g. C) kg. D) metric ton. E) lb

C) kg.

A scientist made careful measurements of the pressure and temperature of many different gases. Based on these measurements, he concluded that "the pressure of a fixed amount of gas, measured at constant volume, is directly proportional to its absolute temperature." This statement is best described as a A) theory. B) hypothesis. C) law. D) experiment. E) definition.

C) law.

Which one of the following numbers contains a digit or digits which is/are not significant? A) 970.0 B) 502 C) 0.300 D) 0.0043 E) 20.01

D) 0.0043

The density of mercury, the only metal to exist as a liquid at room temperature, is 13.6 g/cm3 . What is that density in pounds per cubic inch? Hint: 1 lb = 454 grams A) 849 lb/in3 B) 491 lb/in3 C) 376 lb/in3 D) 0.491 lb/in3 E) 1.83 × 10-3 lb/in3

D) 0.491 lb/in3

Which of the following correctly expresses 52,030.2 m in scientific notation? A) 5.20302 × 104 m B) 5.20302 × 105 m C) 5.203 × 104 m D) 5.20 × 104 m E) 5.2 × 104 m

D) 5.20 × 104 m

Which of the following correctly expresses 0.000007913 g in scientific notation? A) 7.913 × 106 g B) 7.913 × 105 g C) 7.913 × 10-5 g D) 7.913 × 10-6 g E) 7.913 × 10-9 g

D) 7.913 × 10-6 g

Which of the following abbreviations of the given SI base unit is incorrect? A) second: s B) kilogram: kg C) kelvin: K D) mole: m E) ampere: A

D) mole: m

Which one of the following is a "substance" in the sense of the word as used in your textbook? A) air B) tap water C) sea water D) water E) toothpaste

D) water

Select the answer with the correct number of decimal places for the following sum: 13.914 cm + 243.1 cm + 12.00460 cm = A) 269.01860 cm B) 269.0186 cm C) 269.019 cm D) 269.02 cm E) 269.0 cm

E) 269.0 cm

Water vapor is less dense than ice because A) molecules in the gas phase are in constant motion. B) molecules in the gas phase have more potential energy than in solids. C) molecules in the gas phase have more kinetic energy than in solids. D) gaseous molecules have less mass. E) molecules in the gas phase have more space between them than in solids.

E) molecules in the gas phase have more space between them than in solids.

Calculate (to three significant figures) the numerical part of the conversion factors needed to carry out the following unit conversions: a. density in 1.00 g/cm3 to kg/m3 b. area in 1.00 km2 to cm2 c. mass/area of aluminum foil in 1.00 mg/cm2 to g/m2

a. 103 b. 1010 c. 10

Classify the following properties of hydrogen gas as either intensive or extensive. a. the mass of the gas sample b. the average speed of a molecule in the sample c. temperature d. density e. number of molecules present

a. Extensive b. Intensive c. Intensive d. Intensive e. Extensive