Answer:
7628 y
Explanation:
Carbon-14 is radioactive and it follows the first-order kinetics for a radioactive decay. The first-order kinetics may be described by the following integrated rate law:
![ln(\frac{[A]_t}{[A]_o})=-kt](https://tex.z-dn.net/?f=ln%28%5Cfrac%7B%5BA%5D_t%7D%7B%5BA%5D_o%7D%29%3D-kt)
Here:
![[A]_t](https://tex.z-dn.net/?f=%5BA%5D_t)
is the mass, moles, molarity or percentage of the material left at some time of interest t;
![[A]_o](https://tex.z-dn.net/?f=%5BA%5D_o)
is the mass, moles, molarity or percentage of the material initially, we know that initially we expect to have 100 % of carbon-14 before it starts to decay;
is the rate constant;
is time.
The equation becomes:
![ln(\frac{[A]_t}{[A]_o})=-\frac{ln(2)}{T_{\frac{1}{2}}}t](https://tex.z-dn.net/?f=ln%28%5Cfrac%7B%5BA%5D_t%7D%7B%5BA%5D_o%7D%29%3D-%5Cfrac%7Bln%282%29%7D%7BT_%7B%5Cfrac%7B1%7D%7B2%7D%7D%7Dt)
Given:
![\frac{[A]_t}{[A]_o} = \frac{40.0 %}{100.0 %}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BA%5D_t%7D%7B%5BA%5D_o%7D%20%3D%20%5Cfrac%7B40.0%20%25%7D%7B100.0%20%25%7D)
Solve for time:
![t = -\frac{ln(\frac{[A]_t}{[A]_o})\cdot T_{\frac{1}{2}}}{ln(2)}](https://tex.z-dn.net/?f=t%20%3D%20-%5Cfrac%7Bln%28%5Cfrac%7B%5BA%5D_t%7D%7B%5BA%5D_o%7D%29%5Ccdot%20T_%7B%5Cfrac%7B1%7D%7B2%7D%7D%7D%7Bln%282%29%7D)
In this case:
Answer:
Anhydrous calcium chloride dissolves and becomes liquid
Anhydrous copper (ii) sulphate will produce crystal particles
Explanation:
Anhydrous calcium chloride is deliquescent and hence when it is exposed to air, it absorbs water from air. After absorbing water, it dissolves and after some time a pool of clear liquid appears.
Anhydrous copper (ii) sulphate will form crystal structures and the following reaction will takes place
CuSO4 + 5 H20 --> CuSO4.5H2O
MNaHCO₃: 23+1+12+(48×3) = 84g
mCH₃COOH: 12+(1×3)+12+(16×2)+1 = 60g
.................
84g NaHCO₃ react with 60g CH₃COOH
83g NaHCO₃ react with...........
84g ----- 60g
83g ----- X
X = 59,29g CH₃COOH
We used 70g CH₃COOH, it' too much.
So, acetic acid is excess reagent, and sodium bicarbonate is limiting reagent.
_______________________________
B) Amount of CH3COOH is in excess.
:•)
