High School

Astatine-218 has a half-life of 2 seconds. Find the amount left from a 500-gram sample of Astatine-218 after 10 seconds. Round to the nearest hundredth. Include units.

Answer :

Answer:

15.63 grams

Step-by-step explanation:

To find the amount of Astatine-218 left after 10 seconds, we'll use the formula for exponential decay:

[tex]\Large\boxed{\boxed{\sf N = N_0 \times \left( \dfrac{1}{2} \right)^{\frac{t}{T}}}} [/tex]

Where:

  • [tex]\sf N [/tex] is the final amount of Astatine-218.
  • [tex]\sf N_0 [/tex] is the initial amount of Astatine-218 (500 grams in this case).
  • [tex]\sf t [/tex] is the elapsed time (10 seconds in this case).
  • [tex]\sf T [/tex] is the half-life of Astatine-218 (2 seconds in this case).

Substituting the given values:

[tex]\sf N = 500 \times \left( \dfrac{1}{2} \right)^{\frac{10}{2}} [/tex]

[tex]\sf N = 500 \times \left( \dfrac{1}{2} \right)^5 [/tex]

[tex]\sf N = 500 \times \left( \dfrac{1}{32} \right) [/tex]

[tex]\sf N = \dfrac{500}{32} [/tex]

[tex]\sf N \approx 15.625 [/tex]

[tex]\sf N \approx 15.63 \textsf{ grams (in nearest hundredth)} [/tex]

So, the amount of Astatine-218 left from a 500-gram sample after 10 seconds is approximately 15.63 grams.