Cocaine selectively blocks sodium channels which is the mechanism that leads to local anesthetic effects.
Voltage gated sodium channels play very important roles in the body as they are responsible for action initiation and propagation in excitable cells, such as nerves, muscles and neuroendocrine cells. Like other sodium ion channels blockers such as lidocaine, Cocaine selectively blocks sodium ion channels which denies entry of sodium ions in the cell, thus leading to local anesthetic effects.
Electronegativity of an element decreases as we move down a group on the periodic table and electronegativity increases while moving from left to right across a period on the periodic table.
Explanation:
- The electronegativity increases as we move from left to right across a period because from left to right across a period, the nuclear charge is increasing Hence the attraction for the valence electrons also increases.
- As we move down a group, the atoms of each element have an increasing number of energy levels. The distance between the nucleus and valence electron shell increases and reduces the attraction for valence electrons. Hence electronegativity decreases as we move from top to bottom down a group.
Answer:
The activation energy for this reaction = 23 kJ/mol.
Explanation:
Using the expression,
Where,
is the activation energy
R is Gas constant having value = 8.314×10⁻³ kJ / K mol
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T = (280 + 273.15) K = 553.15 K
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T = (376 + 273.15) K = 649.15 K
So,
<u>The activation energy for this reaction = 23 kJ/mol.</u>
Answer:
pH = 12.7
Explanation:
First, we have to calculate the [Ca²⁺] in a solution of about 250 ppm CaCO₃.
Now, let's consider the dissolution of Ca(OH)₂ in water.
Ca(OH)₂(s) ⇄ Ca²⁺(aq) + 2 OH⁻(aq)
The solubility product Ksp is:
Ksp = [Ca²⁺] × [OH⁻]²
[OH⁻] = √(Ksp/[Ca²⁺]) = √(6.5 × 10⁻⁶/2.5 × 10⁻³) = 5.1 × 10⁻² M
Finally, we can calculate pOH and pH.
pOH = -log [OH⁻] = -log (5.1 × 10⁻²) = 1.3
pH + pOH = 14 ⇒ pH = 14 - pOH = 14 - 1.3 = 12.7
