Answer:
The density of Lithium β is 0.5798 g/cm³
Explanation:
For a face centered cubic (FCC) structure, there are total number of 4 atoms in the unit cell.
we need to calculate the mass of these atoms because density is mass per unit volume.
Atomic mass of Lithium is 6.94 g/mol
Then we calculate the mass of four atoms;
⇒next, we estimate the volume of the unit cell in cubic centimeter
given the edge length or lattice constant a = 0.43nm
a = 0.43nm = 0.43 X 10⁻⁹ m = 0.43 X 10⁻⁹ X 10² cm = 4.3 X 10⁻⁸cm
Volume of the unit cell = a³ = (4.3 X 10⁻⁸cm)³ = 7.9507 X 10⁻²³ cm³
⇒Finally, we calculate the density of Lithium β
Density = mass/volume
Density = (4.6097 X 10⁻²³ g)/(7.9507 X 10⁻²³ cm³)
Density = 0.5798 g/cm³
Answer:
46.761g/mol
Explanation:
Given parameters:
Element = Hilarium , Hi
Isotopes: Hi- 45, Hi-46 and Hi- 48
Natural abundance of Hi-45 = 18.3%
Hi-46 = 34.5%
Hi-48 = 47.2%
Unknown:
Atomic weight of naturally occurring Hilarium = ?
Solution:
Isotopes have been studied extensively by mass spectrometry. The method is used to determine the proportion/percentage/fraction by which each of the isotopes of an element occurs in nature. The proportion is called geonormal abundance. From this we can calculate the atomic weight of an element.
We can use the expression below to find this value:
Atomic weight = m₄₅α₄₅ + m₄₆α₄₆ + m₄₈α₄₈
m is the atomic mass of each isotope and α is the abundance
Atomic weight = (45 x 
) + (46 x 
) + (48 x 
)
Atomic weight of Hi = 8.235 + 15.870 + 22.656 = 46.761g/mol
Since the heat of solution of KI is 20.3 kJ/mol, the answer to the question is a. Exothermic, ΔH is positive
There are two types of chemical reactions namely exothermic and endothermic reaction.
- For exothermic reactions, heat is released. So, ΔH is positive
- For endothermic reactions, heat is absorbed. So, ΔH is negative
Given the heat of solution of KI as 20.3 kJ/mol.
Since it is positive, the reaction is exothermic and ΔH is positive
Since the heat of solution of KI is 20.3 kJ/mol, the answer to the question is a. Exothermic, ΔH is positive
Learn more about heat of solution here:
brainly.com/question/15103902
Well, when you leave the water outside, the molecules start to lose some thermal energy and they stop moving, making them more solid and less able to move around. Then, the water turns into ice.
