Answer:
Dissolve the impure solid in a minimal amount of boiling solvent, cool the solution to form crystals, vacuum filter the solution to collect the pure crystals.
Explanation:
Recrystallization is a process when a solid with impurities is purified. To do this a solvent of the compound we want must be used. We need to use only the quantity necessary to dissolve the compound of interest, otherwise, the solvent will dissolve the impurities or it will interfere in the crystallization.
For most of the solids, the solubility increases with the increase of the temperature, so to speed up the process, heat must be added at the system, or the solvent must be boiling. Then, the solution will be cooled to form the crystals of the compound purified, and then it must be filtered in a vacuum because the crystals can slow down the filtration.
Answer:
<h2>775.75 moles</h2>
Explanation:
To find the number of moles in a substance given it's number of entities we use the formula
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
We have the final answer as
<h3>775.75 moles</h3>
Hope this helps you
Thats hard as hell just drop out of the class lol
Answer:- Na = 27.37%, H = 1.20%, C = 14.30% and O = 57.14%
Solution:- For the percentage composition of a compound, the atomic mass of each atoms times its subscript is divided by the molar mass of the compound and multiplied by 100.
The given compound is 
.
mass of Na = 22.99 g
mass of H = 1.008 g
mass of C = 12.01 g
mass of O = 3(16) = 48 g
Molar mass of compound = 22.99 g + 1.008 g + 12.01 g + 48 g = 84.008 g
percentage of Na = 
= 27.37%
percentage of H = 
= 1.20%
percentage of C = 
= 14.30%
percentage of O = 
= 57.14%
We need to first calculate the empirical formula. Empirical formula is the simplest ratio of whole numbers of components in a compound,
Mass percentages have been given. We need to then calculate for 100 g of the compound
C H O
mass 77.87 g 11.76 g <span>10.37 g
number of moles 77.87/12 11.76/1 10.37/16
moles = 6.48 = 11.76 =0.648
divide by least number of moles
6.48/0.648 11.76/0.648 0.648/0.648
= 10 =18.1 = 1
rounded off
C - 10 , H - 18 and O - 1
empirical formula - C</span>₁₀H₁₈O
mass of empirical unit = 12 x 10 + 1x 18 + 16 = 120 + 18 + 16 = 154
number of empirical units = molecular mass / mass of one empirical unit
= 154.25 / 154 = 1.00
Therefore molecular formula = C₁₀H₁₈O
