For the hexagonal close-packed crystal: (12 points) a. How many atoms are associated with the unit cell? b. What is the coordina
1 answer:
Answer :
(a) Total number of atoms in the cell = 6
(b) The coordination number of HCP is, 12
(c) The atomic packing factor is, 74.0 %
Explanation :
<u>Hexagonal close-packed structure (HCP) :</u>
Crystal structure : The manner in which the atoms or ions are spatially arranged.
(a) The HCP unit cell consist of three primitive unit cells in a hexagonal prism. That means, 3 atoms are in the middle layer and 12 atoms are at top and bottom layers and 2 face atoms.
So, the total number of atoms in the cell = 3 + (1/2)×2 + (1/6)×6 × 2 = 6
(b) Coordination number : It is defined as any constituent particle in a crystal is the number of its nearest neighbours.
The coordination number of HCP is, 12
(c) Packing fraction or factor : It is defined as the percentage of the total space filled by the particles.
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Explanation:
C: ΔH=+178 kJ/mol
For an endothermic reaction, heat is getting absorbed during a chemical reaction and is written on the reactant side.
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle. This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.
Treat heat as a reactant and on increasing a reactant at equilibrium, shifts the reaction in the forward direction.
Increase temperature → increase in heat → forward direction
Decrease temperature → decease in heat → backward direction
System C - Increase temperature : Reaction will move forward
System C - Decrease temperature : Reaction will move backward
D: ΔH=−88 kJ/mol
The total enthalpy of the reaction comes out to be negative .
The temperature of the surrounding will increase.
For an exothermic reaction, heat is released during a chemical reaction and is written on the product side.
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle. This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.
Treat heat as a product and on increasing a product at equilibrium, shifts the reaction in the backward direction.
Increase temperature → increase in heat → backward direction
Decrease temperature → decease in heat → forward direction
System D - Increase temperature : Reaction will move backward
System D - Decrease temperature : Reaction will move forward
The correct question is as follows:
How do you convert from grams to moles of a substance
1. Divide by the molar mass
2. Subtract the molar mass
3. Add the molar mass
4. Multiple by the molar mass
Answer: In order to convert from grams to moles of a substance divide by the molar mass.
Explanation:
The number of moles of a substance is the mass of substance in grams divided by its molar mass.
The formula to calculate moles is as follows.
This means that grams are converted to moles when grams is divided by molar mass.
Thus, we can conclude that in order to convert from grams to moles of a substance divide by the molar mass.
<u>Answer:</u> The nuclear equations for the given process is written below.
<u>Explanation:</u>
The chemical equation for the bombardment of neutron to U-238 isotope follows:
Beta decay is defined as the process in which neutrons get converted into an electron and a proton. The released electron is known as the beta particle.
The chemical equation for the first beta decay process of follows:
The chemical equation for the second beta decay process of follows:
Hence, the nuclear equations for the given process is written above.