Answer:
Explanation:
1. pH of original buffer
(a) Calculate pKₐ
(b) Calculate the pH
We can use the Henderson-Hasselbalch equation to get the pH.
![\begin{array}{rcl}\text{pH} & = & \text{pK}_{\text{a}} + \log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\& = & 7.54 +\log \left(\dfrac{0.450}{0.450}\right )\\\\& = & 7.54 + \log1.00 \\ & = & 7.54 + 0.00\\& = & 7.54\\\end{array}](https://tex.z-dn.net/?f=%5Cbegin%7Barray%7D%7Brcl%7D%5Ctext%7BpH%7D%20%26%20%3D%20%26%20%5Ctext%7BpK%7D_%7B%5Ctext%7Ba%7D%7D%20%2B%20%5Clog%20%5Cleft%28%5Cdfrac%7B%5B%5Ctext%7BA%7D%5E%7B-%7D%5D%7D%7B%5Ctext%7B%5BHA%5D%7D%7D%5Cright%20%29%5C%5C%5C%5C%26%20%3D%20%26%207.54%20%2B%5Clog%20%5Cleft%28%5Cdfrac%7B0.450%7D%7B0.450%7D%5Cright%20%29%5C%5C%5C%5C%26%20%3D%20%26%207.54%20%2B%20%5Clog1.00%20%5C%5C%20%26%20%3D%20%26%207.54%20%2B%200.00%5C%5C%26%20%3D%20%26%207.54%5C%5C%5Cend%7Barray%7D)
2. pH after adding strong base
(a) Find new composition of the buffer
The base reacts with the HA and forms A⁻
HA + OH⁻ ⟶ A⁻ + H₂O
I/mmol: 450 40 450
C/mmol: -40 -40 40
E/mmol: 410 0 490
(b) Find the new pH
![\begin{array}{rcl}\text{pH} & = & \text{pK}_{\text{a}} + \log \left(\dfrac{[\text{A}^{-}]}{\text{[HA]}}\right )\\\\& = & 7.54 +\log \left(\dfrac{490}{410}\right )\\\\& = & 7.54 + \log1.195 \\& = & 7.54 +0.0774\\& = & \mathbf{7.62}\\\end{array}\\\text{The new pH is $\large \boxed{\textbf{7.62}}$}](https://tex.z-dn.net/?f=%5Cbegin%7Barray%7D%7Brcl%7D%5Ctext%7BpH%7D%20%26%20%3D%20%26%20%5Ctext%7BpK%7D_%7B%5Ctext%7Ba%7D%7D%20%2B%20%5Clog%20%5Cleft%28%5Cdfrac%7B%5B%5Ctext%7BA%7D%5E%7B-%7D%5D%7D%7B%5Ctext%7B%5BHA%5D%7D%7D%5Cright%20%29%5C%5C%5C%5C%26%20%3D%20%26%207.54%20%2B%5Clog%20%5Cleft%28%5Cdfrac%7B490%7D%7B410%7D%5Cright%20%29%5C%5C%5C%5C%26%20%3D%20%26%207.54%20%2B%20%5Clog1.195%20%5C%5C%26%20%3D%20%26%207.54%20%2B0.0774%5C%5C%26%20%3D%20%26%20%5Cmathbf%7B7.62%7D%5C%5C%5Cend%7Barray%7D%5C%5C%5Ctext%7BThe%20new%20pH%20is%20%24%5Clarge%20%5Cboxed%7B%5Ctextbf%7B7.62%7D%7D%24%7D)
Atoms bond to form molecules: Two or more atoms may bond with each other to form a molecule. When two hydrogens and an oxygen share electrons via covalent bonds, a water molecule is formed.
The higher the energy density of a fuel, the greater the amount of energy it has stored.
<h3>What is the energy density?</h3>
The energy density of a fuel is defined as the amount of energy it possesses per unit volume or per unit weight.
<h3>Characteristics of the energy density</h3>
- It is the amount of energy accumulated in an energy vector per unit volume or mass.
- In general, higher density energy sources and carriers are preferable, as many end uses require concentration of such energy.
- The packaging of energy in liquid hydrocarbons is the one with the highest energy density, that is, the highest energy per volume unit, hence its high use in the transportation sector.
Therefore, we can conclude that in general, fuels, especially low molecular weight fuels, have high energy densities.
Learn more about the energy density here: brainly.com/question/2165966
