Answer:
pH = 2.
Explanation:
A weak acid is in equilibrium with its ions in a solution, so it must have an equilibrium constant (Ka). And, pKa = -logKa
Ka = 10⁻⁴
So, for CH₃COOH the equilibrium must be:
CH₃COOH(aq) ⇄ H⁺(aq) + CH₃COO⁻(aq)
1 M 0 0 Initial
-x +x +x Reacted
1-x x x Equilibrium
And the equilibrium constant:
![Ka = \frac{[H+]x[CH3COO-]}{[CH3COOH]}](https://tex.z-dn.net/?f=Ka%20%3D%20%5Cfrac%7B%5BH%2B%5Dx%5BCH3COO-%5D%7D%7B%5BCH3COOH%5D%7D)
Supposing x << 1:
10⁻⁴ = x²
x = √10⁻⁴
x = 10⁻² M, so the supposing is correct.
So,
pH = -log[H⁺]
pH = -log10⁻²
pH = 2
It took 380,000 years for electrons to be trapped in orbits around nuclei, forming the first atoms.
These were mainly helium and hydrogen, which are still by far the most abundant elements in the universe. Present observations suggest that the first stars formed from clouds of gas around 150–200 million years after the Big Bang. Heavier atoms such as carbon, oxygen and iron, have since been continuously produced in the hearts of stars and catapulted throughout the universe in spectacular stellar explosions called supernovae.
A= Molds and cast fossils
B= Petrification Fossils
C= Whole Body Fossils
D= Footprints and Trackways
