Chapter 18: Problem 24
Potassium-40 has a half-life of \(1.25 \times 10^{9}\) years. How many months will it take for one-half of a \(25.0-g\) sample to disappear?
Short Answer
Expert verified
It takes 1.5 billion months for half the sample to disappear.
Step by step solution
01
Identify the Given Information
Potassium-40 has a half-life of 1.25 billion years and the sample is 25.0 grams. We need to find out how many months it takes for one-half of the sample to disappear.
02
Understanding Radioactive Decay
The half-life of a substance is the time required for half of the sample to decay. After one half-life, half of the initial amount remains.
03
Convert Half-Life to Months
First, convert the given half-life from years to months. Since there are 12 months in a year, multiply the half-life by 12: \(1.25 \times 10^9 \text{ years} \times 12 = 1.5 \times 10^{10} \text{ months} \).
04
Calculate the Time for Half of the Sample to Decay
It takes exactly one half-life for half of the sample to decay. Therefore, the time it will take for one-half of a 25.0-g sample to disappear is 1.5 billion months.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Half-Life Calculation
Radioactive decay is a fundamental concept in understanding how unstable isotopes change over time. The half-life is the period it takes for half of a given sample of a radioactive substance to decay.
Let's break this down with the example of Potassium-40. If you have a 25g sample of Potassium-40, after one half-life, specifically 1.25 billion years, only 12.5g will remain.
To put it simply, the remaining amount decreases by half every half-life. After another 1.25 billion years, you would be left with only 6.25g of Potassium-40. This predictable pattern allows scientists and students alike to calculate how long it takes for radioactive materials to decay to certain levels.
Let's break this down with the example of Potassium-40. If you have a 25g sample of Potassium-40, after one half-life, specifically 1.25 billion years, only 12.5g will remain.
To put it simply, the remaining amount decreases by half every half-life. After another 1.25 billion years, you would be left with only 6.25g of Potassium-40. This predictable pattern allows scientists and students alike to calculate how long it takes for radioactive materials to decay to certain levels.
Potassium-40
Potassium-40 is a radioactive isotope of potassium. It is naturally occurring and widely present in the environment, contributing to natural background radiation. Potassium-40 undergoes radioactive decay to form either Calcium-40 or Argon-40.
This isotope has a half-life of approximately 1.25 billion years, making it very useful in geological dating techniques. By measuring the ratio of Potassium-40 to its decay products in a rock sample, geologists can determine the age of the sample.
Remember, the significance of Potassium-40 in scientific research demonstrates how understanding radioactive decay can impact various fields from geology to archaeology.
This isotope has a half-life of approximately 1.25 billion years, making it very useful in geological dating techniques. By measuring the ratio of Potassium-40 to its decay products in a rock sample, geologists can determine the age of the sample.
Remember, the significance of Potassium-40 in scientific research demonstrates how understanding radioactive decay can impact various fields from geology to archaeology.
Radioactive Isotopes
Radioactive isotopes, or radioisotopes, are atoms with an unstable nucleus that lose energy by emitting radiation. This process is known as radioactive decay. The rate at which a particular radioisotope decays is determined by its half-life.
Isotopes like Potassium-40 have different decay paths based on their nuclear structures. Some decay by emitting alpha particles, others by beta particles, and some via gamma rays. Each type of radiation has unique properties and effects.
The study of radioactive isotopes is crucial not only in academic fields but also in medical treatments, where radioisotopes are used for diagnostic imaging and cancer treatments due to their ability to target and destroy unhealthy cells.
Isotopes like Potassium-40 have different decay paths based on their nuclear structures. Some decay by emitting alpha particles, others by beta particles, and some via gamma rays. Each type of radiation has unique properties and effects.
The study of radioactive isotopes is crucial not only in academic fields but also in medical treatments, where radioisotopes are used for diagnostic imaging and cancer treatments due to their ability to target and destroy unhealthy cells.
Time Conversion
Understanding time conversions in radioactive decay problems is essential for interpreting the results correctly. When dealing with half-life calculations, you often need to convert time units to suit your needs.
For instance, the given half-life of Potassium-40 is in years, but the question asks for the time in months. There are 12 months in a year, so you multiply the number of years by 12. In this example, the conversion is as follows: \( 1.25 \times 10^9 \text{ years} \times 12 = 1.5 \times 10^{10} \text{ months} \).
Being comfortable with these conversions allows you to handle and manipulate data effectively, ensuring you arrive at the correct results. Always double-check your calculations to avoid any mistakes.
For instance, the given half-life of Potassium-40 is in years, but the question asks for the time in months. There are 12 months in a year, so you multiply the number of years by 12. In this example, the conversion is as follows: \( 1.25 \times 10^9 \text{ years} \times 12 = 1.5 \times 10^{10} \text{ months} \).
Being comfortable with these conversions allows you to handle and manipulate data effectively, ensuring you arrive at the correct results. Always double-check your calculations to avoid any mistakes.