Half Life Practice If the halflife of iodine131

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Half Life Practice

Half Life Practice

If the half-life of iodine-131 is 8. 10 days, how long will it take

If the half-life of iodine-131 is 8. 10 days, how long will it take a 50. 00 g sample to decay to 6. 25 g?

What percentage of 50 g is 6. 25 g? 6. 25 g ÷ 50

What percentage of 50 g is 6. 25 g? 6. 25 g ÷ 50 g = 12. 5% How many half-lives leave you with 12. 5% of the parent isotope? 3 If 1 half-life = 8. 1 days, 3 half-lives are equal to 24. 3 days. 8. 1 days × 3 = 24. 3 days

The half-life of hafnium-156 is 0. 025 seconds. How long will it take a

The half-life of hafnium-156 is 0. 025 seconds. How long will it take a 560 g sample to decay to one-fourth of its original mass?

One-fourth is equal to 25%. How many half-lives result in 25% of the parent

One-fourth is equal to 25%. How many half-lives result in 25% of the parent isotope being left? 2 0. 025 seconds/half-life × 2 half-lives= 0. 05 sec

Chromium-48 has a short half-life of 21. 6 hours. How long will it take

Chromium-48 has a short half-life of 21. 6 hours. How long will it take 360. 00 g of chromium-48 to decay to 11. 25 g?

What percentage of 360 g is 11. 25 g? 11. 25 g ÷ 360

What percentage of 360 g is 11. 25 g? 11. 25 g ÷ 360 g × 100% = 3. 125% How many half-lives result in 3. 125% of the parent isotope? 5 If 1 half life = 21. 6 hours, then 5 half-lives would be equal to: 21. 6 hrs × 5 = 108 hrs

Potassium-42 has a half-life of 12. 4 hours. How much of an 848 g

Potassium-42 has a half-life of 12. 4 hours. How much of an 848 g sample of potassium-42 will be left after 62. 0 hours?

*T-chart time! Half Life Amount (g) 0 (initial) 848 1 (12. 4 hours) 424

*T-chart time! Half Life Amount (g) 0 (initial) 848 1 (12. 4 hours) 424 2 (24. 8 hours) 212 3 (37. 2 hours) 106 4 (49. 6 hours) 53 5 (62. 0 hours) 26. 5 OR… 62 hours ÷ 12. 4 hours/HL = 5 Half-Lives 5 half lives leave you with 3. 125% of your parent isotope, so 848 g × 3. 125% = 26. 5 g

Carbon-14 has a half-life of 5730 years. How much of a 144 g sample

Carbon-14 has a half-life of 5730 years. How much of a 144 g sample of carbon-14 will remain after 1. 719 × 104 years?

1. 719 × 104 = 17, 190 years If 1 half-life is equal to

1. 719 × 104 = 17, 190 years If 1 half-life is equal to 5730 years, how many half-lives are in 17, 190 years? 17, 190 years ÷ 5730 years/HL = 3 HL *T-chart time! Half Life Amount (g) 0 144 1 72 2 36 3 18

What is the half-life of a 100. 0 g sample of nitrogen-16 that decays

What is the half-life of a 100. 0 g sample of nitrogen-16 that decays to 12. 5 grams in 21. 6 seconds?

First, we realize that we are left with 12. 5% of the parent isotope

First, we realize that we are left with 12. 5% of the parent isotope (Nitrogen-18). We need to find out how many half-lives leave us with 12. 5% of the parent isotope. 1 half life= 50% parent isotope 2 half lives= 25% parent isotope (half of 50%) 3 half lives= 12. 5% parent isotope (half of 25%) If 21. 6 seconds is enough time for 3 half-lives, 1 half life = 7. 2 seconds. (21. 6 divided by 3)

All isotopes of technetium are radioactive, but they have widely varying half-lives. If an

All isotopes of technetium are radioactive, but they have widely varying half-lives. If an 800. 0 gram sample of technetium 99 decays to 100. 0 g of technetium-99 in 639, 000 years, what is its half-life?

We are left with 100 g out of 800 g. What percentage is that?

We are left with 100 g out of 800 g. What percentage is that? 12. 5% How many half-lives leave us with 12. 5% of the parent isotope? 3 If 3 half-lives are equal to 639, 000 years, how long is 1 half-life? 213, 000

A 208 g sample of sodium-24 decays to 13. 0 g of sodium-24 within

A 208 g sample of sodium-24 decays to 13. 0 g of sodium-24 within 60. 0 hours. What is the half-life of this radioactive isotope?

We are left with 13 g out of 208 g. What percentage is that?

We are left with 13 g out of 208 g. What percentage is that? 13 g ÷ 208 g × 100% = 6. 25% How many half-lives result in 6. 25% of the parent isotope? 4 If 4 half-lives have occurred in 60 hours, how much time is in 1 half-life? 60 hours ÷ 4 half-lives = 15 hours per half-life