Question

Carbon-141414 is an element which loses exactly half of its mass every 573057305730 years. The mass of a sample of carbon-141414 can be modeled by a function, MMM, which depends on its age, ttt (in years). We measure that the initial mass of a sample of carbon-141414 is 741741741 grams. Write a function that models the mass of the carbon-141414 sample remaining ttt years since the initial measurement.

Answer 1

M(t)=741*(1/2)^t/5730

Answer 2

The function that models the mass of the carbon-14 sample remaining t years since the initial measurement is

M(t) = 741 e⁻⁰•⁰⁰⁰¹²¹ᵗ

with M(t) in grams and t in years.

Explanation:

Radioactive reactions always follow a first order reaction dynamic

Let the initial concentration of Carbon-14 be M₀ and the concentration at any time be M

(dM/dt) = -kM (Minus sign because it's a rate of reduction)

(dM/dt) = -kM

(dM/M) = -kdt

∫ (dM/M) = -k ∫ dt

Solving the two sides as definite integrals by integrating the left hand side from M₀ to M and the Right hand side from 0 to t.

We obtain

In (M/M₀) = -kt

(M/M₀) = e⁻ᵏᵗ

M(t) = M₀ e⁻ᵏᵗ

Although, we can obtain k from the information on half life.

For a first order reaction, the rate constant (k) and the half life (T) are related thus

T = (In2)/k

The half life is the time taken for the radioactive substance to decay to hAlf of its original amount, and according to the question, T = 5730 years

k = (In 2)/5730 = 0.000120968 /year. = 0.000121 /year

M(t) = M₀ e⁻ᵏᵗ

k = 0.000121 /year, M₀ = 741 grams

The equation then becomes

M(t) = 741 e⁻⁰•⁰⁰⁰¹²¹ᵗ

with M(t) in grams and t in years.

Hope this Helps!!!