Question

this copy of the exam at home. You are free to use your textbook and notes while completing the exam. You MUST turn in the completed retake by the due date above, no credit will be given if even one day late. The score for this retake will be averaged with your in-class exam score for your final Exam 2 score. 1. (4 pts) Assume nwaccium is a radioactive element that decays into another element over time. If you start with 20,000 atoms of nwaccium, how many atoms of nwaccium will remain after 3 half-lives and 6 half-lives? (Round your answer to the nearest whole atom!) After 3 half-lives: after 6 half-lives: 2. (4 pts) The reaction: 2NOBr(g) 2NO(g) +Br2(g) has a rate law of rate k[NOBr]?. How long would it take for 1.50 M NOBr to be reduced to 0.20 M if the rate constant is 0.80 M's 3. (4 pts) In acidic solution, the breakdown of sucrose into glucose and fructose has the rate law: rate k[H'][sucrose]. The initial rate of sucrose breakdown is measured in a solution that is 0.010 M H 1.0 M sucrose, 0.10 M fructose, and 0.10 M glucose. How much does the rate change if: (Example answers: rate is 5 times as fast or rate is one-tenth as fast)
number 1 thank you.

Answer 1

At each half-life, the number of atoms is divided by 2, then:

3 half-lives = 20000/2/2/2 = 2500 atoms

6 half-lives = 20000/2/2/2/2/2/2 = 312.5 atoms

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