A half-life of mercury-195 is 31 hours. If you start with a sample of 5.00g of pure mercury-195, how much of it will still be present after 93 hours?
0.625
three half lives?
what is 5*1/2*1/2*1/2 ?
Well, mercury-195 sure knows how to be radioactive and disappear over time. With a half-life of 31 hours, we can calculate how much will be left after 93 hours.
After the first 31 hours, half of our sample will remain. So, we're left with 2.50g.
After another 31 hours (62 hours in total), another half will disappear, leaving us with 1.25g.
Now, for the final stretch: after 31 more hours (93 hours in total), we'll lose another half of what's left. This leaves us with a total of 0.625g of shining (or perhaps not shining anymore) mercury-195.
To calculate the amount of mercury-195 that will still be present after 93 hours, we need to determine how many half-lives have occurred within this time frame.
Given that the half-life of mercury-195 is 31 hours, we can divide the total time by the half-life to find the number of half-lives:
93 hours ÷ 31 hours = 3 half-lives
Since each half-life represents a halving of the initial amount, after three half-lives, the remaining amount will be:
(1/2)^3 = 1/8
So, 1/8 of the original amount will still be present.
Calculating the amount:
0.125 × 5.00 g = 0.625 g
Therefore, after 93 hours, approximately 0.625 g of mercury-195 will still be present.
To determine how much of the mercury-195 will still be present after 93 hours, we need to use the concept of half-life.
The half-life of a substance is the time it takes for half of the initial quantity to decay or transform into another substance.
In this case, the half-life of mercury-195 is given as 31 hours.
To find out how many half-lives have passed after 93 hours, we divide the total time by the half-life:
Number of half-lives = 93 hours ÷ 31 hours = 3 half-lives
Since each half-life reduces the quantity by half, after 3 half-lives, the remaining quantity will be (1/2)^3 or (1/8) of the original amount.
Therefore, the remaining quantity of mercury-195 after 93 hours will be:
Remaining quantity = (1/8) × 5.00g = 0.625g
So, after 93 hours, approximately 0.625 grams of mercury-195 will still be present.