Answer:
The length of an edge of this unit cell is 407.294 pm
Explanation:
Face centered cubic structure contains 4 atoms in each unit cell and 12 coordination number, occupying about 74% volume of the total cell. Face centered cubic structure is known for efficient use of space for atom packing.
To determine the edge length, a relationship between the radius of the atom and edge length is used.
X = R√8
Where;
X is the length of an edge of this unit cell
R is the radius of the gold atom = 144 pm = 144 X 10⁻¹² m
X = 144 X 10⁻¹²√8
X = 407.294 X 10⁻¹² m
X = 407.294 pm
Therefore, the length of an edge of this unit cell is 407.294 pm
<u>Ans: Acetic acid = 90.3 mM and Sodium acetate = 160 mM</u>
Given:
Acetic Acid/Sodium Acetate buffer of pH = 5.0
Let HA = acetic acid
A- = sodium acetate
Total concentration [HA] + [A-] = 250 mM ------(1)
pKa(acetic acid) = 4.75
Based on Henderson-Hasselbalch equation
pH = pKa + log[A-]/[HA]
[A-]/[HA] = 10^(pH-pKa) = 10^(5-4.75) = 10^0.25 = 1.77
[A-] = 1.77[HA] -----(2)
From (1) and (2)
[HA] + 1.77[HA] = 250 mM
[HA] = 250/2.77 = 90.25 mM
[A-] = 1.77(90.25) = 159.74 mM
you add the masses of the reactants, because of conservation of mass. if there are two or more products they will ask you to find the mass of only one product or the sum of the mass of all products
