.42; 3.4 divided by 8.1 is about .42
Answer:
After 4 days 10 g will left
After 8 days 5 g will left.
Explanation:
Given data:
Half life of isotope = 4 days
Total amount of sample = 20 g
Amount left after each time period = ?
Solution:
The half life of radioactive isotope is 4 days it means after 4 days the amount left will be half of total amount.
20 g/2 = 10 g
The half amount which is left will be consume in next 4 days and remaining amount will be,
10 g/2 = 5 g
After 4 days 10 g will left
After 8 days 5 g will left.
HBr reacts with LiOH and forms LiBr and H₂O as the products. The balanced reaction is
LiOH(aq) + HBr(aq) → LiBr(aq) + H₂O(l)
Molarity (M) = moles of solute (mol) / volume of the solution (L)
Molarity of LiOH = 0.205 M
Volume of LiOH = 29.15 mL = 29.15 x 10⁻³ L
Hence,
moles of LiOH = molarity x volume of the solution
= 0.205 M x 29.15 x 10⁻³ L
= 5.97575 x 10⁻³ mol
The stoichiometric ratio between LiOH and HBr is 1 : 1.
Hence,
moles of HBr in 25.0 mL = moles of LiOH added
= 5.97575 x 10⁻³ mol
Hence, molarity of HBr = 5.97575 x 10⁻³ mol / 25.00 x 10⁻³ L
= 0.23903 M
≈ 0.239 M
Hence, the molarity of the HBr is 0.239 M.
Answer:
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