All categories

3 years ago

What would the percentage of thorium-232 (parent compound) be in a rock that was dated at 2.8 billions years?

Chemistry

1 answer:

just olya [345]3 years ago

5 0

The half-life of Th-232 is 1.405 × 10¹⁰ years

Time elapsed = 2.8 x 10⁹ years

Equation of radioactive decay:

A = A₀ = (1/2)^ t/t₁/₂

where A₀ is the initial amount, A is the amount after time t, t₁/₂ is the half file

The fraction of thorium-232 that remains in the rock after 2.8 billions years is,

A/A₀ = (1/2) ^ (2.8 x 10⁹/ 1.405 × 10¹⁰) = 0.871

Therefore, the percentage of thorium-232 in the rock that was dated at 2.8 billions year = 87.1%

You might be interested in

83ef0c8

kumpel [21]

Answer:

0.17325 moles per liter per second

Explanation:

For a first order reaction;

in[A] = in[A]o - kt

Where;

[A]= concentration at time t

[A]o = initial concentration

k= rate constant

t= time taken

ln0.5 =ln1 - 2k

2k = ln1 - ln0.5

k= ln1 - ln0.5/2

k= 0 -(0.693)/2

k= 0.693/2

k= 0.3465 s-1

Rate of reaction = k[A]

Rate = 0.3465 s-1 × 0.50 mol/L

Rate = 0.17325 moles per liter per second

5 0

3 years ago

The body gets rid of lactic acid in a chemical pathway that requires ___________. A. carbon dioxide . B. oxygen . C. amino acids

Luden [163]

The body gets rid of acid in a chemical pathway that requires oxygen. The correct answer is B, oxygen.

5 0

3 years ago

Explain the difference between an endothermic and an exothermic reaction using the concepts of potential energy, stability, and

kakasveta [241]

An Exothermic reaction releases energy into the surroundings and so the products have more potential energy then the reactants. The enthalpy change is a negative value. Whereas, an endothermic reaction involves the absorption of energy into the system and so the reactants have more potential energy than the products. The enthalpy change is a positive value. This is clearly represented in energy profile diagrams.

4 0

3 years ago

Which type of reaction happens when a base is mixed with an acid? question 1 options:?

madreJ [45]

Chemicals cancel each other out and produce a salt and water. A neutralization reaction my also occur

7 0

3 years ago

A helium-filled balloon at 310.0 K and 1 atm, contains 0.05 g He, and has a volume of 1.21 L. It is placed in a freezer (T = 235

trapecia [35]

Answer : The value of $\Delta E$ of the gas is 2.79 Joules.