Admin Table of Contents
- 1 What percentage of uranium-238 remains after 2 half lives?
- 2 When a rock formed it contained the parent isotope uranium-238 but it did not contain the daughter isotope which claim describes how this rock would change over time?
- 3 What is the decay product of uranium-238?
- 4 How much uranium 206 is in the rock sample?
- 5 What changes does uranium-238 undergo?
- 6 What is the parent isotope?
- 7 What does the 238 in uranium-238 represent?
- 8 How old would a sample with 50% uranium-238 and 50% lead-206 be?
- 9 How old is the rock if the half life of uranium-238?
- 10 How much Uranium-238 is in a gram of uranium?
- 11 Why does uranium 238 decay faster than uranium 238?
What percentage of uranium-238 remains after 2 half lives?
Due to its natural abundance and half-life relative to other radioactive elements, 238U produces ~40% of the radioactive heat produced within the Earth….Uranium-238.
| General | |
|---|---|
| Neutrons | 146 |
| Nuclide data | |
| Natural abundance | 99.2745% |
| Half-life | 4.468 billion years |
When a rock formed it contained the parent isotope uranium-238 but it did not contain the daughter isotope which claim describes how this rock would change over time?
When a rock formed, it contained the parent isotope, uranium-238, but it did not contain the daughter isotope. How would this rock change over time? The amount of uranium-238 would decrease, and the amount of lead-206 would increase.
How long will it take for a quarter of the uranium-238 atoms in a rock to decay to lead 206?
about 4.5 billion years
Radiometric Dating Some examples: the half-life for the decay of potassium 40 atoms into argon 40 atoms is about 1.3 billion years, the half-life for the decay of uranium 238 into lead 206 is about 4.5 billion years, and the half-life for the decay of carbon 14 into Nitrogen 14 is 5730 years.
What is the decay product of uranium-238?
The nuclear disintegration of uranium-238 forms radium-226 which disintegrates to form radon gas (radon-222). Radon decays to form a series of daughter nuclides, most of which are alpha-particle-releasing isotopes, such as polonium-210.
How much uranium 206 is in the rock sample?
Problem #58: A sample of rock contains 64.27 mg of U-238 (isotopic mass 238.0508 amu) and 22.66 mg of Pb-206 (isotopic mass 205.9745 amu).
How is uranium-238 used to date rocks?
Uranium-238, whose half-life is 4.5 billion years, transmutes into lead-206, a stable end-product. Boltwood explained that by studying a rock containing uranium-238, one can determine the age of the rock by measuring the remaining amount of uranium-238 and the relative amount of lead-206.
What changes does uranium-238 undergo?
Uranium-238 decays by alpha emission into thorium-234, which itself decays by beta emission to protactinium-234, which decays by beta emission to uranium-234, and so on. If inhaled or ingested, however, its radioactivity poses increased risks of lung cancer and bone cancer.
What is the parent isotope?
Isotopes are forms of an element that have the same number of electrons and protons but different numbers of neutrons. Some of these atomic arrangements are stable, and some are not. The original unstable isotope is called the parent isotope, and the more stable form is called the daughter isotope.
How old is a rock which contains uranium-238 and has undergone 2 half lives?
A rock containing U-238 weighs 10 mg when it was unearthed. How much mass of radioactive parent isotope will be present after 4 half-lives. 7. A rock is found to be 2.84 billion years old using U-235 dating….KEY: Half-Life Calculations.
| Element | Carbon |
|---|---|
| Parent Isotope | C-14 |
| Daughter Isotope | N-14 (Nitrogen) |
| Half-life | 5,730 years |
What does the 238 in uranium-238 represent?
The atomic number of uranium (see periodic table) is 92, and the mass number of the isotope is given as 238. Therefore, it has 92 protons, 92 electrons, and 238 — 92 : 146 neutrons. When protons, neutrons, and electrons combine to form an atom, some of their mass is converted to energy and is given off.
How old would a sample with 50% uranium-238 and 50% lead-206 be?
After a second half-life, the 50 gm of U-238 would drop to 25 while the 50 gm of Pb-206 would increase to 75. Thus, two half lives. Since the half-life of U-238 is 4.5 Billion years, this rock must be 9 BY old. 1d.
What is the percent of U 238 remaining?
1. What is Uranium?
| Isotope | Relative Abundance by Weight | Half Life (Years) |
|---|---|---|
| U-238 | 99.28% | 4510000000 |
| U-235 | 0.72% | 710000000 |
| U-234 | 0.0057% | 247000 |
How old is the rock if the half life of uranium-238?
1 (460 7. A rock that originally had a mass of 1.00 gram of uranium-238 now has only 0.50 grams. How old is the rock if the half-live of uranium-238 is 4.5 billions of years. 8. The radioisotope radon-222 has a half-life of 3.8 days.
How much Uranium-238 is in a gram of uranium?
Note: The numbers don’t add up to exactly 100 percent due to rounding. Let’s consider the uranium-238 by itself first, since it makes up more than 99% of natural uranium. The 1.000 gram of uranium contains 0.993 gram of uranium-238. Uranium-238 has a half-life of 4.47 billion years.
How is uranium used to determine the age of rocks?
For example, uranium-238 (which decays in a series of steps into lead-206) can be used for establishing the age of rocks (and the approximate age of the oldest rocks on earth). Since U-238 has a half-life of 4.5 billion years, it takes that amount of time for half of the original U-238 to decay into Pb-206.
Why does uranium 238 decay faster than uranium 238?
The reason is that it has a much shorter half-life, just 245,000 years compared to 4.5 billion years for uranium-238, so it decays much faster. You might also notice the similar decay rates of uranium-238 and uranium-234, both around 12 kBq per gram of natural uranium.