Answer:
19 g
Explanation:
Data Given:
Sodium Chloride (table salt) = 50 g
Amount of sodium (Na) = ?
Solution:
Molecular weight calculation:
NaCl = 23 + 35.5
NaCl = 58.5 g/mol
Mass contributed by Sodium = 23 g
calculate the mole percent composition of sodium (Na) in sodium Chloride.
Since the percentage of compound is 100
So,
Percent of sodium (Na) = 23 / 58.5 x 100
Percent of sodium (Na) = 39.3 %
It means that for ever gram of sodium chloride there is 0.393 g of Na is present.
So,
for the 50 grams of table salt (NaCl) the mass of Na will be
mass of sodium (Na) = 0.393 x 50 g
mass of sodium (Na) = 19 g
The formula of the hydrate = CuSO₄• 3H₂O
<h3>Further explanation</h3>
Given
4.175 grams sample CuSO₄• xH₂O
3.120 grams anhydrous compound CuSO₄
Required
The formula
Solution
mass of H₂O driven off :
= 4.175 - 3.12
= 1.055 g
MW CuSO₄ = 159.5 g/mol
MW H₂O = 18 g/mol
mol ratio of CuSO₄ : H₂O :
= 3.12/159.5 : 1.055/18
= 0.01956 : 0.05861
= 1 : 3
The half-life of Plutonium−239, t1/2 is 2.41 × 10⁴<span> yrs
time taken to reach tolerable level = seven half-lives
= 7 x t1/2
= 7 x </span>2.41 × 10⁴ yrs
= 168700 yrs
= 1.687 x 10⁵ yrs
Hence, the period of time that <span>Plutonium-239 must be stored is </span>1.687 x 10⁵ years.
