2Ca + O2 = 2CaO
First, determine which is the excess reactant
72.5 g Ca (1 mol) =1.8089725036
(40.078 g)
65 g O2 (1 mol) =2.0313769611
(15.999g × 2)
Since the ratio of to O2 is 2:1 in the balanced reaction, divide Ca's molar mass by 2 to get 0.9044862518. this isn't necessary because Ca is already obviously the limiting reactant. therefore, O2 is the excess reactant.
Now do the stoichiometry
72.5 g Ca (1 mol Ca) (1 mol O2)
(40.078 g Ca)(2 mol Ca)(31.998g O2)
=0.0282669621 g of O2 left over
Answer: :))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))
Explanation:
The quantity of substance remains after 850 years is 8.98g if the half life of radioactive radium is 1,599 years.
<h3>What is half life period? </h3>
The time taken by substance to reduce to its half of its initial concentration is called half life period.
We will use the half- life equation N(t)
N e^{(-0.693t) /t½}
Where,
N is the initial sample
t½ is the half life time period of the substance
t2 is the time in years.
N(t) is the reminder quantity after t years .
Given
N = 13g
t = 350 years
t½ = 1599 years
By substituting all the value, we get
N(t) = 13e^(0.693 × 50) / (1599)
= 13e^(- 0.368386)
= 13 × 0.691
= 8.98
Thus, we calculated that the quantity of substance remains after 850 years is 8.98g if the half life of radioactive radium is 1,599 years.
learn more about half life period:
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El número de Avogadro es 6,022 x 10^23, y es el número de átomos que hay en un mol de dicho elemento. A su vez un mol es la cantidad de un elemento cuya masa en gramos coincide con el peso atómico.
Por tanto, 6,022 x 10^23 átomos del elemento tienen una masa en gramos igual a su peso atómico. Hacemos una regla de tres:
1 gramo -------- 1,5 x 10^22 átomos
x ------------------ 6,022 x 10^23 átomos
=> x = 40,1 gramos por mol del elemento.
De modo que su peso atómico es 40,1. Se trata del calcio.
Saludos.
