Answer:
0.314 s⁻¹
Step-by-step explanation:
Use the <em>Arrhenius equation.</em>
Data:
k₁ = 0.0275 s⁻¹; k₂ = ?
Eₐ = 75.5 kJ·mol⁻¹
T₁ = 20 °C = 293.15 K; T₂ = 45°C = 318.15 K
<em>Calculation:
</em>
k₂ = 0.0275 × 11.41
k₂ = 0.314 s⁻¹
Answer:
Explanation:
Caffeine is a weak base with pKb = 10.4
Kb = 10⁻¹⁰°⁴ = 3.98 x 10⁻¹¹
molecular weight of caffeine = 194.2
455 x 10⁻³ g / L = 455 x 10⁻³ / 194.2 moles / L
concentration of given solution a = 2.343 x 10⁻³ M
Let the caffeine be represented by B .
B + H₂O = BH + OH⁻
a - x x x
x² / ( a - x ) = Kb
x² / ( a - x ) = 3.98 x 10⁻¹¹
x is far less than a so a -x is almost equal to a
x² = 3.98 x 10⁻¹¹ x 2.343 x 10⁻³ = 9.32 x 10⁻¹⁴
x = 3.05 x 10⁻⁷
[ OH⁻ ] = 3.05 x 10⁻⁷
pOH = - log ( 3.05 x 10⁻⁷ )
= 7 - log 3.05
= 7 - 0.484 = 6.5
pH = 14 - 6.5 = 7.5
Explanation:
To determine the charge on a given transition metal atom, you have to consider what element it is, the charges on the other atoms in the molecule, and the net charge on the molecule itself. The charges are always whole numbers, and the sum of all the atomic charges equals the charge on the molecule
Answer:
If the atom has more electrons than protons, it is a negative ion or ANION. If it has more protons than electrons, it is a positive ion.
Explanation:
Positive ions are typically metals or act like metals. Many common materials contain these ions. Mercury is found in thermometers, for instance, and aluminum is a metal that is found in a surprising amount of things.
