4...........................
Answer:
b. primitive cubic < body-centered cubic < face-centered cubic
Explanation:
The coordination number is defined as <em>the number of atoms (or ions) surrounding an atom (or ion) in a crystal lattice</em>. Its value gives us a measure of how tightly the spheres are packed together. The larger the coordination number, the closer the spheres are to each other.
- In the <u>primitive cubic</u>, each sphere is in contact with 6 spheres, so its <u>coordination number is 6</u>.
- In the <u>body-centered cubic</u>, each sphere is in contact with 8 spheres, so its <u>coordination number is 12</u>.
- In the <u>face-centered cubic</u>, each sphere is in contact with 12 spheres, so its <u>coordination number is 12</u>.
Therefore, the increasing order in density is the primitive cubic first, then the body-centered cubic, and finally the face-centered cubic.
Answer:
6.4 g BaSO₄
Explanation:
You have been given the molarity and the volume of the solution. To find the mass of the solution, you need to (1) find the moles BaSO₄ (via the molarity ratio) and then (2) convert moles BaSO₄ to grams BaSO₄ (via the molar mass). It is important to arrange the conversions in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 2 sig figs to reflect the sig figs of the given values.
Molarity (mol/L) = moles / volume (L)
(Step 1)
55 mL / 1,000 = 0.055 L
Molarity = moles / volume <----- Molarity ratio
0.5 (mol/L) = moles / 0.055 L <----- Insert values
0.0275 = moles <----- Multiply both sides by 0.055
(Step 2)
Molar Mass (BaSO₄): 137.33 g/mol + 32.065 g/mol + 4(15.998 g/mol)
Molar Mass (BaSO₄): 233.387 g/mol
0.0275 moles BaSO₄ 233.387 g
--------------------------------- x ------------------- = 6.4 g BaSO₄
1 mole
This must be a universal indicator, the pH is going down everytime you add more :)
