What is the mass of an original 5.60-gram sample of iron-53 that remains unchanged after 25.53 minutes?(1) 0.35g
(2) 1.40 g(3) 0.70 g
(4) 2.80 g

Respuesta :

Answer:

(3) 0.70 g

Explanation:

Half life of iron-53 = 8.5167 minutes

[tex]t_{1/2}=\frac {ln\ 2}{k}[/tex]

Where, k is rate constant

So,  

[tex]k=\frac {ln\ 2}{t_{1/2}}[/tex]

[tex]k=\frac{ln\ 2}{8.5167}\ min^{-1}[/tex]

The rate constant, k = 0.08138 min⁻¹

Time = 25.53 minutes

Using integrated rate law for first order kinetics as:

[tex][A_t]=[A_0]e^{-kt}[/tex]

Where,  

[tex][A_t][/tex] is the concentration at time t

[tex][A_0][/tex] is the initial concentration  = 5.60 g

So,  

[tex]\frac{[A_t]}{5.60}=e^{-0.08138\times 25.53}[/tex]

[tex][A_t]=\frac{5.6}{e^{2.0776314}}[/tex]

[tex][A_t]=0.70\ g[/tex]

Answer- (3) 0.70 g

Answer:

After 25.53 minutes there will remain 0.70 grams of the iron-53 sample. Option 3 is correct.

Explanation:

Step 1: Data given

Original mass of the original iron sample = 5.60 grams

Half life of iron-53 = 8.5167 minutes

Step 2: Calculate the rate constant

k = (ln 2)/(t1/2)

⇒ with k = the rate constant

⇒ with t1/2 = the half-life time = 8.5167 minutes

k = 0.08139 / min

Step 3: Calculate the mass after 25.53 minutes

At = A0*e^(-kt)

⇒ with At = the amount of iron sample after 25.53 minutes

⇒ A0 = the initial amount of iron sample =5.50 grams

⇒ with k =  0.08139 / min

⇒ with t = the time = 25.53 minutes

At = 5.50*e^(-0.08139*25.53)

At = 0.70 grams

After 25.53 minutes there will remain 0.70 grams of the iron-53 sample