The way an experiment is carried is out is determined by the purpose of that experiment.
Answer: 
Explanation: Because barium is in Group 2, it forms ions with a charge of +2. Fluorine, in Group 17, form ions with a charge of -1. Cross the charges to get the subscripts (Since Ba has a charge of +2, F has a subscript of 2. Because F has a charge of -1, Ba needs a subscript of 1). Therefore, a formula unit of the compound is .
First, find the number of moles of UF6
Avagadro's number = 6.023 x 10^23
Number of moles = 8.0 x 10^26 / Avagadro's number = 8.0 x 10^26 / 6.023 x 10^23 = 1.328 x 10³ moles
Molecular weight of UF6 = Molecular weight of U (238.02891) + Molecular weight of F6 (6 x 18.9984032) = 238.02891 + 113.9904192 = 352.0193292 g/mol
Therefore mass of 8.0 x 10^26 UF6 molecules = 352.0193292 g/mol x 1.328 x 10³ moles = 467.481669 x 10³ grams
The volume of O₂ : 21 L
<h3>Further explanation</h3>
Given
8.7 grams of C₂H₄
Required
Volume O₂
Solution
Reaction
C₂H₄ + 3 O₂ ⇒ 2 CO₂ + 2 H₂O
mol C₂H₄(MW= 28 g/mol) :
= mass : MW
= 8.7 g : 28 g/mol
= 0.311
From the equation, mol O₂ :
= 3/1 x mol C₂H₄
= 3/1 x 0.311
= 0.933
At STP, 1 mol gas=22.4 L, so for 0.933 mol :
= 0.933 x 22.4 L
= 20.899 L ≈ 21 L
