Problems A
39
8. The wavelengths of X rays characteristic of certain metallic targets are (a)
copper, 1.537395 A; (b) chromium, 2.28503 A; (c) molybdenum, 0.70783 A:
(d) tungsten, 0.20862 A. Express these wavelengths in centimeters.
9. If the laboratory temperature is 21°C, what is the Fahrenheit temperature?
10. When the temperature gets to -50°F in Siberia, what would be the temperature on the Celsius and Kelvin scales?
11. Mercury freezes at -38.87°C. What are the freezing points on the Fahrenheit
and Kelvin scales?
12. What is the Fahrenheit temperature at absolute zero (0 K)?
13. At what temperature do the Fahrenheit and Celsius scales have the same
reading?
14. Light travels at a speed of 3.0 x 10
10 cm/sec. A light-year is the distance that
light can travel in a year's time. If the sun is 93,000,000 miles away, how many
light-years is it from the earth?
15. If 1 ml of water is spread out as a film 3 A thick, what area in square meters
will it cover?
16. The area of a powdered material is 100 trr/g. What volume of water is required
to form a film 10 A thick over the surface?
17. An agate marble is placed in a graduated cylinder containing 35.0 ml of water.
After the marble is added, the surface of the water stands at 37.5 ml. Find the
diameter and surface area of the marble.
18. (a) If there are 6.02 x 10
23 molecules in 18 ml of water, what is the volume
occupied by one molecule? (b) If the molecules were little spheres, what
would be the radius of a water molecule? (Give the answer in angstroms.)
19. If you should decide to establish a new temperature scale based on the assumptions that the melting point of mercury (-38.9°C) is 0°M and the boiling
point of mercury (356.9°C) is 100°M, what would be (a) the boiling point of
water in degrees M, and (b) the temperature of absolute zero in degrees M?
20. It has been found that the percentage of gold in sea water is 2.5 x 10~'°. How
many tons of sea water would have to be processed in order to obtain 1.0 g of
gold?
21. A solution contains 5.0 g of sodium hydroxide per liter. How many grams will
be contained in 50 ml?
22. A solution contains 40 g of potassium nitrate per liter. How many milliliters of
this solution will be needed in order to get 8.0 g of potassium nitrate?
23. The neck of a volumetric flask has an internal diameter of 12 mm. The usual
practice is to fill a volumetric flask until the liquid level (meniscus) comes just
to the mark on the neck. If by error one drop (0.050 ml) too much is added, at
how many millimeters above the mark on the neck will the meniscus stand?
Assume a plane (not curved) meniscus.
39
8. The wavelengths of X rays characteristic of certain metallic targets are (a)
copper, 1.537395 A; (b) chromium, 2.28503 A; (c) molybdenum, 0.70783 A:
(d) tungsten, 0.20862 A. Express these wavelengths in centimeters.
9. If the laboratory temperature is 21°C, what is the Fahrenheit temperature?
10. When the temperature gets to -50°F in Siberia, what would be the temperature on the Celsius and Kelvin scales?
11. Mercury freezes at -38.87°C. What are the freezing points on the Fahrenheit
and Kelvin scales?
12. What is the Fahrenheit temperature at absolute zero (0 K)?
13. At what temperature do the Fahrenheit and Celsius scales have the same
reading?
14. Light travels at a speed of 3.0 x 10
10 cm/sec. A light-year is the distance that
light can travel in a year's time. If the sun is 93,000,000 miles away, how many
light-years is it from the earth?
15. If 1 ml of water is spread out as a film 3 A thick, what area in square meters
will it cover?
16. The area of a powdered material is 100 trr/g. What volume of water is required
to form a film 10 A thick over the surface?
17. An agate marble is placed in a graduated cylinder containing 35.0 ml of water.
After the marble is added, the surface of the water stands at 37.5 ml. Find the
diameter and surface area of the marble.
18. (a) If there are 6.02 x 10
23 molecules in 18 ml of water, what is the volume
occupied by one molecule? (b) If the molecules were little spheres, what
would be the radius of a water molecule? (Give the answer in angstroms.)
19. If you should decide to establish a new temperature scale based on the assumptions that the melting point of mercury (-38.9°C) is 0°M and the boiling
point of mercury (356.9°C) is 100°M, what would be (a) the boiling point of
water in degrees M, and (b) the temperature of absolute zero in degrees M?
20. It has been found that the percentage of gold in sea water is 2.5 x 10~'°. How
many tons of sea water would have to be processed in order to obtain 1.0 g of
gold?
21. A solution contains 5.0 g of sodium hydroxide per liter. How many grams will
be contained in 50 ml?
22. A solution contains 40 g of potassium nitrate per liter. How many milliliters of
this solution will be needed in order to get 8.0 g of potassium nitrate?
23. The neck of a volumetric flask has an internal diameter of 12 mm. The usual
practice is to fill a volumetric flask until the liquid level (meniscus) comes just
to the mark on the neck. If by error one drop (0.050 ml) too much is added, at
how many millimeters above the mark on the neck will the meniscus stand?
Assume a plane (not curved) meniscus.