Explanation:
a positively charged nucleus is surrounded by mostly empty space.
Answer:
0.01395mol Cr2O3
Explanation:
the molar mass of Cr2O3 is 151.9904 g/mol
2.12g Cr2O3 x 1 mol/151.9904g = 0.01395mol Cr2O3
You must know the concentration of the acetic acid. Suppose the concentration is 0.1 M. The solution is as follows:
CH₃COOH → CH₃COO⁻ + H⁺
I 0.1 0 0
C -x +x +x
E 0.1 - x x x
Ka = (x)(x)/(0.1 - x)
1.8×10⁻⁵ = x²/(0.1 - x)
Solving for x,
x = 1.333×10⁻³ = H⁺
pH = -log[H⁺] = -log(1.333×10⁻³)
pH = 2.88
Answer:
It takes 1.32x10⁻⁷s for the concentration of A to fall by a factor of 8
Explanation:
The equation that represents a first-order kinetics is:
Ln ([A] / [A]₀] = -kt
<em>Where [A] is actual concentration, [A]₀ is initial concentration, K is rate constant (For the given problem, 1.57x10⁷s⁻¹ and t is time.</em>
<em />
As you want the time when you have [A] in a factor of 8 = [A] / [A]₀ = 1/8
Replacing:
Ln ([A] / [A]₀] = -kt
Ln (1/8) = -1.57x10⁷s⁻¹*t
t = 1.32x10⁻⁷s
<h3>It takes 1.32x10⁻⁷s for the concentration of A to fall by a factor of 8</h3>
Answer:
Metallic bonding
Explanation:
Metals have low ionization energies. Therefore, their valence electrons are easily delocalized (attracted to the neighbouring metal atoms). These delocalized electrons are then not associated with a specific metal atom. Since the electrons are “free”, the metal atoms have become cations, and the electrons are free to move throughout the whole crystalline structure.
We say that a metal consists of an array of cations immersed in a sea of electrons
.
The electrons act as a “glue” holding the cations together.
Metallic bonds are the attractive forces between the metal cations and the sea of electrons.
In an NaK alloy, for example, the Na and K atoms contribute their valence electrons to the "sea". The atoms aren’t bonded to each other, but they are held in place by the metallic bonding.