Iridium-192 is used in cancer treatment, a small cylindrical piece of 192 Ir, 0.6 mm in diameter (0.3mm radius) and 3.5 mm long, is surgically inserted into the tumor. if the density of iridium is 22.42 g/cm3, how many iridium atoms are present in the sample?
Let us start by computing for the volume of the cylinder. V = π(r^2)*h where r and h are the radius and height of the cylinder, respectively. Let's convert all given dimensions to cm first. Radius = 0.03 cm, height is 0.35cm long.
V = π * (0.03cm)^2 * 0.35 cm = 9.896*10^-4 cm^3
Now we have the volume of 192-Ir, let's use the density provided to get it's mass, and once we have the mass let's use the molar mass to get the amount of moles. After getting the amount of moles, we use Avogadro's number to convert moles into number of atoms. See the calculation below and see if all units "cancel":
9.896*10^-4 cm^3 * (22.42 g/cm3) * (1 mole / 191.963 g) * (6.022x10^23 atoms /mole)
= 6.96 x 10^19 atoms of Ir-122 are present.
Answer:
10. Stacey
11. 7.86 g/cm^3 (3dp)
OR 786 kg/m^3 (SI units)
Explanation:
10. The correct exact answer for 10 is 26.169 (6.71x3.9). While Sam was correct in the precision of the number (2dp just like the given measurements), he was incorrect in the number itself. While Stacy's number was not as precise as Sam's (0dp), it is correctly rounded to the nearest whole number, therefore Stacy is correct.
11. The formula for density is mass/volume. The mass here is 264g and the volume is 33.6ml, therefore the density is 7.86 (3 sig figs because given values had 3) g/cm^3, because the mass was given in grams and 1ml = 1cm^3. Converted to SI units it is 786 kg/m^3.
Hope this helped!
The heat capacity or thermal capacity of a body is the quotient between the amount of heat energy transferred to a body or system in any process and the change in temperature it experiences. In a more rigorous form, it is the energy necessary to increase the temperature of a certain substance by one temperature unit. [1] It indicates the greater or lesser difficulty that said body presents in experiencing changes in temperature under the supply of heat. It can be interpreted as a measure of thermal inertia. It is an extensive property, since its magnitude depends not only on the substance but also on the amount of matter in the body or system; therefore, it is characteristic of a particular body or system. For example, the heat capacity of the water in an Olympic-size swimming pool will be greater than that of the water in a glass. In general, heat capacity also depends on temperature and pressure.
Explanation:
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Answer:
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