Answer:
5.625 grams
Explanation:
Start your equation with what you have been given. Place the units you need in your answer on the right side of the equal sign.
225mg
----------- X ----------- X ------------- = ? g
lb
Now start to fill in your equation and use a conversions to get rid of the units you don't want. Convert mg into grams first. The child's weight (25 lb) is placed over 1 just to get the equation lined up properly so you can see how the units cancel out.
225 mg 1 g 25 lb 5.625 g
--------------- X --------------- X ------------- = ---------------
lb 1000 mg 1 1
The lb on the top and bottom cancel each other out and you are left with just grams. Even though it is over one, that is the same at just 5.625 grams.
Answer:
![[A_t]=54.5\ g](https://tex.z-dn.net/?f=%5BA_t%5D%3D54.5%5C%20g)
Explanation:
Given that:
Half life = 14.0 days
Where, k is rate constant
So,
The rate constant, k = 0.04951 days⁻¹
Initial concentration [A₀] = 60.0 g
Time = 46.7 hrs
Considering, 1 hr = 0.041667 days
So, time = 1.9458 days
Using integrated rate law for first order kinetics as:
![[A_t]=[A_0]e^{-kt}](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5BA_0%5De%5E%7B-kt%7D)
Where,
![[A_t]](https://tex.z-dn.net/?f=%5BA_t%5D)
is the concentration at time t
So,
![[A_t]=60.0\times e^{-0.04951\times 1.9458}\ g](https://tex.z-dn.net/?f=%5BA_t%5D%3D60.0%5Ctimes%20e%5E%7B-0.04951%5Ctimes%201.9458%7D%5C%20g)
Radioactive decay is a pseudo-first order reaction. When you know the half-life of the material, you could use this equation.
A= A₀(1/2)^t/h
where
A is the final activity
A₀ is the initial activity
t is the time
h is the half-life
A = (0.64)(1/2)^88/44 = <em>0.16 mbq</em>
