Knowee
Questions
Features
Study Tools

The half life for the radioactive decay of potassium-40 to argon-40 is ×1.26109 years.Suppose nuclear chemical analysis shows that there is 0.362mmol of argon-40 for every 1.000mmol of potassium-40 in a certain sample of rock. Calculate the age of the rock.Round your answer to 2 significant digits.

Question

The half life for the radioactive decay of potassium-40 to argon-40 is ×1.26109 years.Suppose nuclear chemical analysis shows that there is 0.362mmol of argon-40 for every 1.000mmol of potassium-40 in a certain sample of rock. Calculate the age of the rock.Round your answer to 2 significant digits.

🧐 Not the exact question you are looking for?Go ask a question

Solution

To solve this problem, we need to use the formula for radioactive decay, which is:

N = N0 * (1/2)^(t/T)

where: N is the final quantity of the substance N0 is the initial quantity of the substance t is the time that has passed T is the half-life of the substance

In this case, we know that the final quantity of potassium-40 (N) is 1.000mmol - 0.362mmol = 0.638mmol (because the amount of argon-40 represents the amount of potassium-40 that has decayed). The initial quantity (N0) is 1.000mmol, and the half-life (T) is 1.26109 years.

We can plug these values into the formula and solve for t:

0.638mmol = 1.000mmol * (1/2)^(t/1.26109 years)

To isolate t, we can take the natural logarithm of both sides and rearrange the equation:

ln(0.638) = ln(1.000 * (1/2)^(t/1.26109 years)) ln(0.638) = ln(1.000) + (t/1.26109 years) * ln(1/2) t = 1.26109 years * (ln(0.638) - ln(1.000)) / ln(1/2)

Calculating the right-hand side gives us the age of the rock. Please note that you need to use a calculator that can handle natural logarithms to get the numerical result.

This problem has been solved

Similar Questions

The half life for the radioactive decay of rubidium-87 to strontium-87 is ×4.881010 years.Suppose nuclear chemical analysis shows that there is 0.486mmol of strontium-87 for every 1.000mmol of rubidium-87 in a certain sample of rock. Calculate the age of the rock.Round your answer to 2 significant digits.

The half life for the radioactive decay of carbon-14 to nitrogen-14 is ×5.73103 years.Suppose nuclear chemical analysis shows that there is 0.414mmol of nitrogen-14 for every 1.000mmol of carbon-14 in a certain sample of rock. Calculate the age of the rock.Round your answer to 2 significant digits.

Metamorphic rock shows that only 25% of its original potassium-40 remains. What is the minimum age of the rock? The half-life of K-40 is 1.3 billion years. billion years

Suppose the amount of a certain radioactive substance in a sample decays from 9.70mg to 3.90mg over a period of ×3.23103 years. Calculate the half life of the substance.Round your answer to 2 significant digits.

Strontium-90 is radioactive and has a half life of 28.8 years. How much of a 2.20mg sample would be left after 117. years?Round your answer to 2 significant digits. Also, be sure your answer has a unit symbol.

1/3

Upgrade your grade with Knowee

Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.