Chemistry, 04.10.2019 23:00 natalieburnett82

The table shows the amount of radioactive element remaining in a sample over a period of time.

radioactive decay rate

amount of radioactive sample

(grams) time

(years)

56.0 0

47.1 400

39.6 800

33.3 1,200

28 1,600

part 1: what is the half-life of the element? explain how you determined this.

part 2: how long would it take 312 g of the sample to decay to 9.75 grams? show your work or explain your answer.

Answers: 1

Show answers

Answers

Answer from: xxhighwolfxx7508

8,000 year.

Explanation:

It is known that the decay of a radioactive isotope isotope obeys first order kinetics.Half-life time is the time needed for the reactants to be in its half concentration.If reactant has initial concentration [A₀], after half-life time its concentration will be ([A₀]/2).Also, it is clear that in first order decay the half-life time is independent of the initial concentration.

Part 1: What is the half-life of the element? Explain how you determined this.

The half-life of the element is 1,600 years.

Half-life time is the time needed for the reactants to be in its half concentration.

The sample stats with 56.0 g and reaches its half concentration (28.0 g) after 1,600 years.

So, the half-life of the sample is 1,600 years.

Part 2: How long would it take 312 g of the sample to decay to 9.75 grams? Show your work or explain your answer.

For, first order reactions:

k = ln(2)/(t1/2) = 0.693/(t1/2).

Where, k is the rate constant of the reaction.

t1/2 is the half-life of the reaction.

∴ k =0.693/(t1/2) = 0.693/(1,600 years) = 4.33 x 10⁻⁴ year⁻¹.

Also, we have the integral law of first order reaction:

kt = ln([A₀]/[A]),

where, k is the rate constant of the reaction (k = 4.33 x 10⁻⁴ year⁻¹).

t is the time of the reaction (t = ??? year).

[A₀] is the initial concentration of the sample ([A₀] = 312.0 g).

[A] is the remaining concentration of the sample ([A] = 9.75 g).

∴ t = (1/k) ln([A₀]/[A]) = (1/4.33 x 10⁻⁴ year⁻¹) ln(312.0 g/9.75 g) = 8,000 year.

Answer from: whiteshawn02

Half life of the sample= 1600 years

Part 2: 8000 years

Explanation:

The half life of a radioactive substance is the time taken for the substance to decay to half its initial amount.

Since 56.0g of radioactive material was present at t= 0 years. Half of 56.0g is 28.0g hence the time taken to have 28.0g of the sample left is the half life of the material.

If the original sample contained 312g of radioactive material

First half life. 156g left

Second half life. 78 g left

Third half life. 39gleft

Fourth half life. 19.5 g left

Fifth half life. 9.75 g

If each half life takes 1600 years then five half life will take 5×1600= 8000 years

Answer from: Quest

the mass of the cathode increases because ions from the solution get reduced to atoms and become part of the cathode.

explanation:

subscribe to my yt channel yoongi jmz

follow my insta yoongi_jams

stan bts

Answer from: Quest

give me abc and i will get it for u.

Another question on Chemistry

Chemistry, 22.06.2019 01:30

When an object falls through the air and encounters air resistance its overall speed will be than if it had not encountered air resistance? (one word answer)

Answers: 2

Answer

Chemistry, 22.06.2019 08:30

Joan writes four numbers on the board in standard form, and then she writes their scientific notation

Answers: 1

Answer

Chemistry, 22.06.2019 12:30

The melting point of sulfur is 115 °c and its boiling point is 445 °c. what state would sulfur be in at 200 °c?

Answers: 1

Answer

Chemistry, 22.06.2019 13:00

Lab reagent, hypothesis test.a reference solution used as a lab reagent is purported to have a concentration of 5 mg/dl. six samples are taken from this solution and the following concentrations are recorded: (5.32, 4.88, 5.10, 4.73, 5.15, 4.75) mg/dl.these six measurements are assumed to be an srs of all possible measurements from solution.they are also assumed to have a standard deviation of 0.2, a normal distributin, and a mean concentration equal to the true concentration of the solution.carry out a significance test to determine whether these six measurements provide reliable evidence that the true concentration of the solution is actually not 5 mg/dl.

Answers: 1

Answer

You know the right answer?

The table shows the amount of radioactive element remaining in a sample over a period of time.
...

Questions