The half-life of a reaction, t1/2, is the time it takes for the reactant concent

Question

The half-life of a reaction, t1/2, is the time it takes for the reactant concentration A to decrease by half. For example, after one half-life the concentration falls from the initial concentration [Al to [Alo/2, after a second half-life to [Ao/4, after a third half-life to [Alo/8, and so on. on For a first-order reaction, the half-life is constant. It depends only on the rate constant k and not on the reactant concentration. It is expressed as For a second-order reaction, the half-life depends on the rate constant and the concentration of the reactant and so is expressed as 1/2A Part A A certain first-order reaction (A-products) has a rate constant of 7.50×10-3 s-1 at 45 °C. How many minutes does it take for the concentration of the reactant, [A, to drop to 6.25 % of the original concentration? Express your answer with the appropriate units View Available Hint(s) Value Units Submit Part B A certain second-order reaction (Bproducts) has a rate constant of 1.25×10-3 Ms at 27 C and an initial half-life of 216 s. What is the concentration of the reactant B after one half-life? Express your answer with the appropriate units

Explanation / Answer

A. In this part we need four half life to make it 6.25% of the initial concentration.

So t=0.693×4/7.50×10^-3

t=369.6 seconds.

B. The initial concentration will be

t×rateconstant

Which is 216×1.25×10^-3 =0.27M

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.