Lisa’s doctor tells her that she needs to eat more foods that contain calcium to maintain her bone health. What could happen if
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Answer:
The order of energy released per mass is
CH₃OH (-2.268 × 10⁴ kJ/kg) < C₈H₁₈ (-4.826 × 10⁴ kJ/kg) < H₂ (-2.835 × 10⁵ kJ/kg)
Explanation:
In order to calculate the enthalpy of a reaction (ΔH°r) we can use the following expression.
ΔH°r = ∑np × ΔH°f(p) - ∑nr × ΔH°f(r)
where
ΔH°f(i) are the enthalpies of formation of reactants and products
ni are the moles of reactants and products
<u>Combustion of hydrogen</u>
H₂(g) + 1/2 O₂(g) ⇒ H₂O(l)
ΔH°r = 2 mol × ΔH°f(H₂O) - 1 mol × ΔH°f(H₂) - 1/2 mol × ΔH°f(O₂)
ΔH°r = 2 mol × (-285.8 kJ/mol) - 1 mol × 0 - 1/2 mol × 0
ΔH°r = -571.6 kJ
571.6 kJ are released when 1 mole of H₂ is burned. The amount of heat released per kilogram is:
<u>Combustion of methanol</u>
CH₃OH(l) + 3/2 O₂(g) ⇒ CO₂(g) + 2 H₂O(l)
ΔH°r = 1 mol × ΔH°f(CO₂) + 2 mol × ΔH°f(H₂O) - 1 mol × ΔH°f(CH₃OH) - 3/2 mol × ΔH°f(O₂)
ΔH°r = 1 mol × (-393.5 kJ/mol) + 2 mol × (-285.8 kJ/mol) - 1 mol × (-238.4 kJ/mol) - 3/2 mol × 0
ΔH°r = -726.7 kJ
726.7 kJ are released when 1 mole of CH₃OH is burned. The amount of heat released per kilogram is:
<u>Combustion of octane</u>
C₈H₁₈(l) + 12.5 O₂(g) ⇒ 8 CO₂(g) + 9 H₂O(l)
ΔH°r = 8 mol × ΔH°f(CO₂) + 9 mol × ΔH°f(H₂O) - 1 mol × ΔH°f(C₈H₁₈) - 12.5 mol × ΔH°f(O₂)
ΔH°r = 8 mol × (-393.5 kJ/mol) + 9 mol × (-285.8 kJ/mol) - 1 mol × (-208.4 kJ/mol) - 12.5 mol × 0
ΔH°r = -5511.8 kJ
5511.8 kJ are released when 1 mole of C₈H₁₈ is burned. The amount of heat released per kilogram is:
Answer: The order from weakest to strongest is:
Explanation:
Dispersion force is the weakest intermolecular force. It is a temporary attractive force that come into action when the electrons in two neighboring atoms are at the positions which results in formation of temporary dipoles.
Dipole interaction is an attractive interaction between the positive end and negative end of the polar molecule.
Hydrogen bond is a weak bond between two adjacent molecules due to an electrostatic attraction between a hydrogen atom in a molecule with an electronegative atom of an adjacent molecule.
Single covalent bond is more stronger bond than the the interaction stated above because there is sharing of an electron between two atoms.
Ionic bond is the strongest bonds in which complete transfer of electrons is present. Due to high electronegativity difference between the bonded atoms there is a high electrostatic interaction between the oppositely charged ions which makes ionic bond strongest from all the other types of the bonds.
So, the order is: