Answer:
2.7 x 10^-19 J
Explanation:
The formula needed for this problem is
E = hν
where E = energy, h = Planck's constant = 6.626x10^-34 and ν is the frequency
c = λν
where c = speed of light = 3x10^8, and λ = wavelength
3x10^8 = 7.35x10^-7 . ν
ν = 4.08 x 10^14 Hz
E = 6.626x10^-34 . 4.08x10^14 = 2.7 x 10^-19 J
Answer:
the standard enthalpy of formation of this isomer of C₈H₁₈ (g) = -375 kj/mol
Explanation:
The given combustion reaction
C₈H₁₈ + 25/2 O₂ → 8 CO₂ + 9 H₂O ............................(1)
Heat of reaction or enthalpy of combustion = -5099.5 kj/mol
from equation (1)
ΔH⁰reaction = (Enthalpy of formation of products - Enthalpy of formation of reactants)
Or, - 5099.5 = [8 x ΔH⁰f(CO₂) +9 x ΔH⁰f(H₂O)] - [ΔH⁰f(C₈H₁₈) + ΔH⁰f(O₂)].................................(2)
Given ΔH⁰f(CO₂) = - 393.5 kj/mol & ΔH⁰f(H₂O) = - 285.8 kj/mol and ΔH⁰f(O₂)= 0
Using equation (2)
ΔH⁰f(C₈H₁₈) = -621 kj/mol
Answer:
See explanation
Explanation:
Poor irrigation: When too much water is used during irrigation or water is inefficiently used for irrigation purposes, there could be an overall decrease in the availability of water resources leading to vegetation loss and desertification. Therefore, water resources should be properly managed to avoid desertification.
Overgrazing: Overgrazing refers to excessive grazing of a grassland. When livestock are allowed to overgraze on a particular area, there is vegetation loss and consequent desertification. Grazing practices should be organized in such a way that grasslands are not subjected to overgrazing.
Poor tillage practices: Poor tillage practices such as continuous cropping makes the soil more porous and exposes the soil to erosion. There may be vegetation loss and finally desertification. Sustainable tillage practices such as shifting cultivation and bush fallowing should be adopted.
There is no single chemical composition that characterizes all glass. Typical glass contains formers, flexes, and stabilizers. Formers make up the largest percentage of the mixture to be melted. And typical soda-lime-silica glass the former is silica (silicon dioxide) in the form of sand.
