Chapter 20: Problem 65
Tritium \(\left({ }^{3} \mathrm{H}\right)\) is radioactive and decays by electron emission. Its half-life is 12.5 years. In ordinary water the ratio of \({ }^{1} \mathrm{H}\) to \({ }^{3} \mathrm{H}\) atoms is \(1.0 \times 10^{17}\) to \(1 .\) (a) Write a balanced nuclear equation for tritium decay. (b) How many disintegrations will be observed per minute in a 1.00-kg sample of water?
Short Answer
Step by step solution
Understanding Tritium Decay
Writing the Nuclear Equation
Calculating Number of Tritium Atoms
Calculating Decay Constant
Calculating Disintegrations Per Minute
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Radioactivity
Some important points about radioactivity include:
- It is a random, spontaneous process.
- A radioactive material continuously emits radiation over time.
- The rate of emission decreases as the material becomes more stable.
Half-Life Calculation
To calculate the decay constant (\(\lambda\)), we use: \(\lambda = \frac{\ln 2}{T_{1/2}}\), where \(T_{1/2}\) is the given half-life. For tritium:
- Convert years to minutes for precision in scientific calculations.
- Use the decay constant in determining the rate of decay over time.
Beta Decay
During beta decay:
- A neutron is converted into a proton, leading to the emission of an electron and an antineutrino.
- This conversion increases the atomic number of the element by one, thus transforming tritium into helium.
- The mass number remains the same since the transformation involves particles with similar masses.
Nuclear Equations
- The superscripts denote the atomic mass number, indicating the number of protons and neutrons.
- The subscripts denote the atomic number, representing the number of protons in the nucleus.
- The equation maintains the balance of mass and charge, ensuring both are conserved in the reaction.