To completely describe an electron in an atom, four quantum numbers are needed: energy (n), angular momentum (ℓ), magnetic moment (mℓ), and spin (ms). The first quantum number describes the electron shell, or energy level, of an atom.
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.
Solution: Change in state of matter is a physical change because of the physical condition and appearance changes but not the chemical composition.
The lithosphere is divided into large tectonic plates.
The major plates include the North American,Antarctic ,African ,pacific,
European,South American and the indo-Australian. Each plate consists of dense organic material as well a less dense crust material.
(The answers are in the paragraph)
Answer:
9.28 g/L
Explanation:
We will be using the ideal gas law to solve this problem:
PV = nRT where P is the pressure (atm)
V is the volume (L)
R is the gas constant 0.08205 Latm/Kmol
T is the temperature (K)
n is the number of moles
The number of moles is the mass divided by the molecular weight, and from here we can solve for the density. (Note here we use the atomic weight of radon since its is a monoatomic noble gas)
PV = m/AW RT ⇒ P = (m/V ) RT/AW ⇒ P AW /RT =D
0.950 atm x 222.0 g/mol / [( 0.08205 Latm/Kmol ) x 277 K ] = D
9.28 g/L = D
