Explanation:
According to mass action,
![\textrm{rate}=-\dfrac{\Delta[\textrm A]}{2\Delta t}=k[\textrm A]^2](https://tex.z-dn.net/?f=%5Ctextrm%7Brate%7D%3D-%5Cdfrac%7B%5CDelta%5B%5Ctextrm%20A%5D%7D%7B2%5CDelta%20t%7D%3Dk%5B%5Ctextrm%20A%5D%5E2)
Where, k is the rate constant
So,
![\dfrac{d[A]}{dt}=-k[A]^2](https://tex.z-dn.net/?f=%5Cdfrac%7Bd%5BA%5D%7D%7Bdt%7D%3D-k%5BA%5D%5E2)
Integrating and applying limits,
![\int_{[A_t]}^{[A_0]}\frac{d[A]}{[A]^2}=-\int_{0}^{t}kdt](https://tex.z-dn.net/?f=%5Cint_%7B%5BA_t%5D%7D%5E%7B%5BA_0%5D%7D%5Cfrac%7Bd%5BA%5D%7D%7B%5BA%5D%5E2%7D%3D-%5Cint_%7B0%7D%5E%7Bt%7Dkdt)
we get:
![\dfrac{1}{[A]} = \dfrac{1}{[A]_0}+kt](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7B%5BA%5D%7D%20%3D%20%5Cdfrac%7B1%7D%7B%5BA%5D_0%7D%2Bkt)
Where,
![[A_t]](https://tex.z-dn.net/?f=%5BA_t%5D)
is the concentration at time t
![[A_0]](https://tex.z-dn.net/?f=%5BA_0%5D)
is the initial concentration
Half life is the time when the concentration reduced to half.
So, ![[A_t]=\frac{1}{2}\times [A_0]](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5Cfrac%7B1%7D%7B2%7D%5Ctimes%20%5BA_0%5D)
Applying in the equation as:
![t_{1/2}=\dfrac{1}{k[A_o]}](https://tex.z-dn.net/?f=t_%7B1%2F2%7D%3D%5Cdfrac%7B1%7D%7Bk%5BA_o%5D%7D)
To calculate the pH of this solution, we use the
Henderson-Hasselbalch equation:
pH = pKa + log ([A-]/[HA])
Where,
[A-] = Molarity of the conjugate base =
CH3COO- = 0.29 M<span>
<span>[HA] = Molarity of the weak acid = CH3COOH = 0.18 M</span></span>
pKa = dissociation constant of the weak acid =
4.75
When KOH is added to the buffer, the chemical
reaction is:
CH3COOH + KOH = CH3COO-K+ + H2O
Therefore when 0.0090 mol KOH is added, 0.0090
mol acid is neutralized, and 0.0090 mol CH3COO- is produced.
[CH3COO-] = [0.0090 mol + 0.375 L (0.29 mol/L) ]
/ 0.375 L = 0.314 M
[CH3COOH] = [-0.0090 mol + 0.375 L (0.18 mol/L) ]
/ 0.375 L = 0.156 M
Going back to Henderson-Hasselbalch
equation:
pH = 4.75 + log (0.314 / 0.156)
<span>pH = 5.054</span>
Answer:
The answer to your question is letter B
Explanation:
a. [: C≡C :] This option is not correct because Carbon only has 4 valence electrons and carbons in this structure have 5, this structure does not exist.
b. [: N≡N :] This option is correct because because Nitrogen has 5 valence electrons and this structure shows that number of electrons.
c. No right choice. This option is incorrect because letter B is correct.
I can't find the c orrect ratio in the selection. The formula for beryl is Be3Al2(SiO3)6 so it should be 3:2:6.
