Problems B
99
28. The density of Dowmetal, a magnesium alloy, is 1.78 g/ml. Find the weight (in
grams) of a rod i inch in diameter and 2 ft long.
29. Neptunium has a density of 17.7 g/ml. What would be the radius of a sphere of
neptunium that weighed 500 g?
30. Gallium (density = 3.01 g/ml) may be purchased at the rate of $6.90 per gram.
How much does 1 cu ft of gallium cost?
31. When 235 g of uranium-235 disintegrates by nuclear fission, 0.205 g is converted into 4.4 x 10'- calories (4.4 million million calories!) of energy. What
volume of uranium is converted to energy if its density is 18.9 g/ml?
32. (a) Find a general factor by which pounds per cubic foot could be multiplied
to convert to density in grams per milliliter.
(b) Find a factor to convert grams per milliliter to pounds per cubic foot.
33. A metal earring weighs 2.6321 g when suspended in air. When immersed in
water at 22°C, it weighs 2.3802 g. What is the density of the earring?
34. A thousandth of a milliliter is called a lambda (X). A certain biochemical
procedure calls for the addition of 5 X of a 2.00% solution of sodium chloride
(density = 1.012 g/ml). How many milligrams of sodium chloride will be added
from the 5 X pipet?
35. The weight of a metal sample is measured by finding the increase in weight of
a volumetric flask when the metal sample is placed in it. The volume of the
metal sample is measured by finding how much less water the volumetric flask
holds when it contains the metal sample. Compute the density of the metal
sample from the following data, assuming that the density of the water is 1.000
g/ml.
Weight of empty flask = 23.482 g
Weight of flask + sample = 40.375 g
Weight of flask + sample + water = 63.395 g
Weight of flask + water (without sample) = 48.008 g
36. (a) Repeat the calculations of Problem 35, using an exact density value for
water (refer to Table 7-1) and assuming a temperature of 68°F.
(b) In which decimal place does it make a significant difference if the exact
density for water is used instead of the approximate value of 1 g/ml?
37. A chemical is soluble in water but insoluble in kerosene. As a consequence,
kerosene may be used to determine its density. The density of kerosene is
0.735 g/ml at 22°C. From the following data (obtained as in Problem 35),
compute the density of the sample.
Weight of empty flask = 28.176 g
Weight of flask + sample = 40.247 g
Weight of flask + sample + kerosene to fill = 51.805 g
Weight of flask + kerosene (without sample) = 45.792 g
99
28. The density of Dowmetal, a magnesium alloy, is 1.78 g/ml. Find the weight (in
grams) of a rod i inch in diameter and 2 ft long.
29. Neptunium has a density of 17.7 g/ml. What would be the radius of a sphere of
neptunium that weighed 500 g?
30. Gallium (density = 3.01 g/ml) may be purchased at the rate of $6.90 per gram.
How much does 1 cu ft of gallium cost?
31. When 235 g of uranium-235 disintegrates by nuclear fission, 0.205 g is converted into 4.4 x 10'- calories (4.4 million million calories!) of energy. What
volume of uranium is converted to energy if its density is 18.9 g/ml?
32. (a) Find a general factor by which pounds per cubic foot could be multiplied
to convert to density in grams per milliliter.
(b) Find a factor to convert grams per milliliter to pounds per cubic foot.
33. A metal earring weighs 2.6321 g when suspended in air. When immersed in
water at 22°C, it weighs 2.3802 g. What is the density of the earring?
34. A thousandth of a milliliter is called a lambda (X). A certain biochemical
procedure calls for the addition of 5 X of a 2.00% solution of sodium chloride
(density = 1.012 g/ml). How many milligrams of sodium chloride will be added
from the 5 X pipet?
35. The weight of a metal sample is measured by finding the increase in weight of
a volumetric flask when the metal sample is placed in it. The volume of the
metal sample is measured by finding how much less water the volumetric flask
holds when it contains the metal sample. Compute the density of the metal
sample from the following data, assuming that the density of the water is 1.000
g/ml.
Weight of empty flask = 23.482 g
Weight of flask + sample = 40.375 g
Weight of flask + sample + water = 63.395 g
Weight of flask + water (without sample) = 48.008 g
36. (a) Repeat the calculations of Problem 35, using an exact density value for
water (refer to Table 7-1) and assuming a temperature of 68°F.
(b) In which decimal place does it make a significant difference if the exact
density for water is used instead of the approximate value of 1 g/ml?
37. A chemical is soluble in water but insoluble in kerosene. As a consequence,
kerosene may be used to determine its density. The density of kerosene is
0.735 g/ml at 22°C. From the following data (obtained as in Problem 35),
compute the density of the sample.
Weight of empty flask = 28.176 g
Weight of flask + sample = 40.247 g
Weight of flask + sample + kerosene to fill = 51.805 g
Weight of flask + kerosene (without sample) = 45.792 g