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Problem 21a,b
Label each of the following as either a physical process or a chemical process: (a) crushing a metal can (b) production of urine in the kidneys
Problem 21c,d,e
Label each of the following as either a physical process or a chemical process: (c) melting a piece of chocolate (d) burning fossil fuel (e) discharging a battery.
Problem 22
A match is lit and held under a cold piece of metal. The following observations are made: (a) The match burns. (b) The metal gets warmer. (c) Water condenses on the metal. (d) Soot (carbon) is deposited on the metal. Which of these occurrences are due to physical changes, and which are due to chemical changes?
- Which separation method is better suited for obtaining sugar from cane juice—filtration or evaporation?
Problem 23
- A silvery metal is put inside a beaker of water. Bubbles form on the surface of the metal, and it dissolves gradually. (b) Do you expect the remaining solution to be a pure substance or a mixture?
Problem 24
Problem 24a
A silvery metal is put inside a beaker of water. Bubbles form on the surface of the metal and it dissolves gradually. (a) Is this an example of a chemical or a physical change?
- Convert this energy to calories. When the bullet is stopped by a bulletproof vest, which form of energy does the kinetic energy of the bullet convert to?
Problem 25
Problem 25a
(a) Calculate the kinetic energy, in joules, of a 15-g bullet moving at 120 m/s.
Problem 27b
Two positively charged particles are first brought close together and then released. Once released, the repulsion between particles causes them to move away from each other. (b) Does the potential energy of the two particles prior to release increase or decrease as the distance between them is increased.
Problem 28
For each of the following processes, does the potential energy of the object(s) increase or decrease? (b) Water is pumped from ground level to the reservoir of a water tower 30 m above the ground.
Problem 29
What is the kinetic energy and velocity of the aluminum sphere in Problem 1.4 at the moment it hits the ground? (Assume that energy is conserved during the fall and that 100% of the sphere's initial potential energy is converted to kinetic energy by the time impact occurs.)
Problem 31a
Convert the following expressions into exponential notation: (a) 3 terameters (tm)
Problem 31b,c
Convert the following expressions into exponential notation: (b) 2.5 femtoseconds (fs) (c) 57 micrometers (mm)
Problem 31d
Convert the following expressions into exponential notation: (d) 8.3 megagrams (mg).
Problem 32c
Use appropriate metric prefixes to write the following measurements without use of exponents: (a) 7.29×106 g (b) 6.1×10-10 m (c) 1.828×10-3 s
Problem 32d
Use appropriate metric prefixes to write the following measurements without use of exponents: (d) 3.523×109 m3 (e) 9.62×102 m/s (f) 8.923×10-12 kg
Problem 32g
Use appropriate metric prefixes to write the following measurements without use of exponents: (g) 3.552×1012 L.
Problem 33a,b
Make the following conversions: (a) 83 °F to °C (b) 29 °C to °F
Problem 33c
Make the following conversions: (c) 294 °C to K
Problem 33d
Make the following conversions: (d) 832 K to °C
Problem 33f
Make the following conversions: (f) 35 °F to K.
Problem 34a
(a) A child has a fever of 101 °F. What is the temperature in °C?
Problem 34b
(b) In a desert, the temperature can be as high as 45 °C, what is the temperature in °F?
Problem 35a
(a) A sample of tetrachloroethylene, a liquid used in dry cleaning that is being phased out because of its potential to cause cancer, has a mass of 40.55 g and a volume of 25.0 mL at 25 °C. What is its density at this temperature? Will tetrachloroethylene float on water? (Materials that are less dense than water will float.)
Problem 35b
(b) Carbon dioxide (CO2) is a gas at room temperature and pressure. However, carbon dioxide can be put under pressure to become a 'supercritical fluid' that is a much safer dry-cleaning agent than tetrachloroethylene. At a certain pressure, the density of supercritical CO2 is 0.469 g/cm3. What is the mass of a 25.0-mL sample of supercritical CO2 at this pressure?
- (a) What is the mass of a silver cube whose edges measure 2.00 cm each at 25 _x001F_C? The density of silver is 10.49 g/cm3 at 25 _x001F_C. (b) The density of aluminum is 2.70 g/cm3 at 25 _x001F_C. What is the weight of the aluminum foil with an area of 0.5 m2 and a thickness of 0.5 mm?
Problem 36
Problem 37b
(b) An experiment requires 45.0 g of ethylene glycol, a liquid whose density is 1.114 g/mL. Rather than weigh the sample on a balance, a chemist chooses to dispense the liquid using a graduated cylinder. What volume of the liquid should he use?
Problem 37c
(c) Is a graduated cylinder such as that shown in Figure 1.21 likely to afford the accuracy of measurement needed?
Problem 37d
(d) A cubic piece of metal measures 5.00 cm on each edge. If the metal is nickel, whose density is 8.90 g/cm3, what is the mass of the cube?
Problem 38a
(a) After the label fell off a bottle containing a clear liquid believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0-mL portion of the liquid had a mass of 21.95 g. A chemistry handbook lists the density of benzene at 15 °C as 0.8787 g/mL. Is the calculated density in agreement with the tabulated value?