Equation for Half life :
A = a(0.5)^(t/h)
A is current amount, "a" is initial amount, h is halflife, t is time
5 = 40(0.5)^(t/1.3x10^9)
5/40 = (0.5)^(t/1.3x10^9)
take the log of both sides , power rule
Log(5/40) = (t/1.3x10^9) * Log(0.5)
(1.3x10^9) * Log(5/40) / Log(0.5) = t
3.9x10^9 years = t
And if you think about what a half life is, the time it take for the amount to reduce to half.
40/2 = 20
20/2 = 10
10/2 = 5
It went through 3 half-lifes
3 * 1.3x10^9 = 3.9x10^9 years
Answer & Explanation:
The given number above, 0.002353, may be rounded to only two significant figures by adding 1 to the 3 which is in the fourth place of the decimal position. This becomes, 0.0024. Addition of 1 was done because the number that follows 3 in the original number is 5.
<u>Answer:</u> The molar concentration of NaOH in the final diluted solution is 0.056 M
<u>Explanation:</u>
To calculate the molarity of solution, we use the equation:
Given mass of NaOH = 4.00 g
Molar mass of NaOH = 40 g/mol
Volume of solution = 5.00 mL
Putting values in above equation, we get:
To calculate the molarity of the diluted solution, we use the equation:
where,
are the molarity and volume of the concentrated NaOH solution
are the molarity and volume of diluted NaOH solution
We are given:
Putting values in above equation, we get:
Hence, the molar concentration of NaOH in the final diluted solution is 0.056 M
The moles of Al that is needed to react with 6.34 moles of Fe3O4 is 16.9 moles
<u><em> Explanation</em></u>
<em> </em>8 Al+ 3Fe3O4 → 4 Al2O3 + 9Fe
use of mole ratio of Al: fe3O4 to calculate the moles of Al
The mole ratio of Fe3O4 : Al is 8:3 therefore the moles of Al =
6.34 moles x8/3 = 16.9 moles
Answer:
The answer to your question is Gallium-71 = 70.9202 amu
Explanation:
Gallium atomic weight = 69.7
Gallium-69 = 68.9 amu abundance = 60.4%
Gallium-71 = x abundance = 39.6%
To solve this problem just write an equation and solve it for the mass of gallium-71.
Equation
Gallium = Gallium-69(abundance) + Gallium-71(abundance)
Substitution
69.7 = (68.9)(0.604) + Gallium-71(0.396)
69.7 = 41.6156 + Gallium-71(0.396)
Gallium-71(0.396) = 69.7 - 41.6156
Gallium-71(0.396) = 28.0844
Gallium-71 = 28.0844/0.396
Gallium-71 = 70.9202 amu