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How much of 80g of sodium-23 (na) is left after 4 half-lives if each half-life is 2.6 years?
Jazmyn Coleman
By tabultion starting at 80 g
#1 half life = 40 g
#2 half life = 20g
#3 half life = 10g
#4 half life = 5 g
However, scientists use the equation
Half-lef = 1/2^(n)
Mass remaining after 'n' half lives. = M(o) X `1/2^(n)
So in this case
mass remaining after 4 half-lives = 80 x 1/2(4) =>
80 x 2^-4 =
80 x 0.0625 = 5 g
lenpollock
Willis Lavis
Each half-life of sodium-23 is 2.6 years, so 4 half-lives is 4 * 2.6 = 10.4 years.
After 10.4 years, only 80g * (1/2)^4 = 80g * (1/16) = 5g of sodium-23 would be left
Iconic
After 4 half-lives, 5% of the original amount of sodium-23 (Na) is left, so 0.8g of sodium-23 (Na) is left.
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