How long will it take for 475 mg of a sample of radium-225, which has a half-life of about 15 days, to decay to 30 mg
1 answer:
<h3>Answer:</h3>
60 days
<h3>Explanation:</h3>Half-life is the amount of time it takes half of a substance to decay away.
Guess and Check
One method for solving half-life problems like this is to guess and check. To do this, we can continue to divide 475mg by 2 until we get to 30mg.
- 475 ÷ 2 = 237.5
- 237.5 ÷ 2 = 118.75
- 118.75 ÷ 2 = 59.375
- 59.375 ÷ 2 = 29.6875
As seen here, it takes approximately 4 half-lives for this sample of Ra-225 to decay to 30mg. Now, we can multiply 4 by the length of the half-life, 15 days.
- 4 * 15 = 60 days.
Fractions
Another way to solve this is to use fractions.
- 30 is about 1/16 of 475
- 16 is equivalent to
.
This means that it takes 4 half-lives for 475mg to decay to 30mg. Using the same method above, we can tell that 4 half-lives are 60 days.
Important Note
In this question, I rounded occasionally. So, not all of the values are exact, but they are all very close.
You might be interested in
The climate controls that best explains the difference in average daytime temperature variation from month to month between Seattle and Fargo as well as between Dublin and Moscow is latitude
- Latitude is simply known as the highest force behind differences in temperature which also are fluctuations in incoming solar radiation. It alters (change) the angle of the sun and length of daylight control of the global distribution of temperature.
- The 2 factors that causes this alterations or changes in latitude are therefore sun angle and length of daylight.
- Latitudes is known to show how much of the changes or variation in average temperature at a fixed latitude, average daytime temperature variation and seasonal fluctuations in temperature.
Conclusively, we can say that The climate controls that best explains the difference in average daytime temperature variation from month to month between Seattle and Fargo as well as between Dublin and Moscow is latitude
Learn more from
