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If a solution containing 18.0 g of a substance reacts by first-order kinetics, how many grams remain after three half-lives?

Respuesta :

Edufirst
Answer: 2.25 g

Explanation:

1) The half-life is the fime for which the initial concentration is decreased by half of the original concentration.

2) So, after every period of one half-life the concentration of the reactant will decrease by half.


3) In this case after 3 half-lives, the concentration will decrease by half 3 times which is 2^3 = 8

So, the amount that will remain will be 18.0 g / 8 = 2.25 g.

4) You can do it in 3 stages in this way:

One half-life => 18.0g / 2 = 9.0 g

Two half-lives => 9.0g / 2 = 4.5 g

Three half-lives => 4.5 g / 2 = 2.25 g
mickymike92

Based on the number of half-lives undergone by the substance,  the mass of the substance remaining after three half-lives is 2.25 g.

What is half-life of a substance?

The half-life of a substance is the time it will take for half the amount of the substance to decay or decompose.

The initial mass of the substance is 18.0 g

The substance undergoes three half-lives.

After the first half-life, mass remaining = 18/2 = 9.0 g

After the first half-life, mass remaining = 18/2 = 9.0 g

After the third half-life, mass remaining = 4.5/2 = 2.25 g

Therefore, the mass of the substance remaining after three half-lives is 2.25 g.

Learn more about half-life at: https://brainly.com/question/2320811

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