a 15g sample of gold-198 decays in 3g in 6 days. how much will be left after 8 days?
If you mean radioactive decay, it's physics, not chemistry. Anyways, you might want to take a look at the half life formulas of radioactive decay.
Who says it's physics and not chemistry. It's both but chemistry uses this all of the time. In fact my Ph. D. dissertation used radioactive Co, Mo, Cu, In, and Zn to prove what I had to prove.
ln(No/N) = kt
No = 15
N = 3
k = ?
t = 3 days
Solve for k.
Then use ln(No/N) = kt again.
No = 15
N = ?
k = from above
t = 8 days.
To determine how much gold-198 will be left after 8 days, we need to calculate the rate of decay and then apply it to the remaining mass.
The rate of decay can be calculated using the formula:
Rate of decay = (Initial mass - Final mass) / Time
In this case, the initial mass is 15g, the final mass is 3g, and the time is 6 days.
Rate of decay = (15g - 3g) / 6 days = 2g/6 days = 1/3 g/day
Now, we can calculate how much gold-198 will be left after 8 days.
Amount left = Initial mass - (Rate of decay * Time)
Initial mass = 15g
Rate of decay = 1/3 g/day
Time = 8 days
Amount left = 15g - (1/3 g/day * 8 days)
= 15g - (8/3)g
= (45g - 8g) / 3
= 37g / 3
Therefore, after 8 days, approximately 12.33g (37g / 3) of gold-198 will be left.