Answer is: Kb for methylamine is 4.37·10⁻⁴.<span>
Chemical reaction: CH</span>₃NH₂ + H₂O → CH₃NH₃⁺ + OH⁻.
c(CH₃NH₂) = 0.253 M.
α = 4.07% ÷ 100% = 0.0407.
[CH₃NH₃⁺] = [OH⁻] = c(CH₃NH₂) · α.
[CH₃NH₃⁺] = [OH⁻] = 0.253 M · 0.0407.
[CH₃NH₃⁺] = [OH⁻] = 0.0103 M.
[CH₃NH₂] = 0.253 M - 0.0103 M.
[CH₃NH₂] = 0.2427 M.
Kb = [CH₃NH₃⁺] · [OH⁻] / [CH₃NH₂].
Kb = (0.0103 M)² / 0.2427 M.
Kb = 4.37·10⁻⁴.
Answer:
THE MASS OF 7.68 *10^24 MOLECULES OF PHOSPHORUS TRICHLORIDE IS 1746.25 g.
Explanation:
Molar mass of PCl3 = ( 31 + 35.5 *3) = 137.5 g/mol
At 7.68 * 10^24 molecules, how many number of mole is present?
6.03 * 10^23 molecules = 1 mole
7.68*10^24 molecules = x mole
x mole = 7.68 *10^24 molecules/ 6.03 *10^23
x mole = 1.27 *10 moles
x mole = 12.7 moles
Using mole = mass / molar mass
mass = mole * molar mass
mass = 12.7 moles * 137.5 g/mol
mass = 1746.25 g
Hence, the mass of 7.68 *10^24 molecules is 1746.25 g
Answer:
A. It has a partial negative charge on oxygen and a partial positive charge on hydrogen.
Explanation:
There is an electronegativity difference between O and H atoms. The electronegativity value of O and H are 3.5 and 2.1 respectively. So the electronegativity different of the O-H bond is 3.5- 2.1 = 1.4 thus making the O-H bond polar. O being the more electronegative bond acquires a partial negative charge and H acquires a partial positive charge.
Answer:
, 
, 
, 
Explanation:
The four most abundant minerals in the continental crust are, , , , .
The percentages are
is called quartz
is called corundum
is called calcium oxide or quick lime
is called magnesium oxide or magnesia
Answer:
ΔH = -976.5 kJ
Explanation:
For the reaction given, there are 2 moles of benzene (C6H6). The heat of this reaction is -6278 kJ, which means that the combustion of 2 moles of benzene will lose 6278 kJ of heat. It is an exothermic reaction.
The value of ΔH, the enthalpy, is a way of measurement of the heat, and it depends on the quantity of the matter (number of moles).
So, 24.3 g of benzene has :
n = mass/ molar mass
n = 24.3/78.11
n = 0.311 moles
2 moles ------------ -6278 kJ
0.311 moles ----------- x
By a simple direct three rule:
2x = -1953.08
x = -976.5 kJ
