The standard heat of formation is the energy change that occurs when 1 mole of a substance is made from its elements in their standard states ( most stable form of the element at 1 bar of pressure and the specified temperature, usually 298 K or 25 degrees Celcius)
E.g for MgCO3
Mg (s) + C (s) + 3/2 O2 (g) = MgCO3
C) They have more than two carbons that are bonded to only one other carbon
Answer:
900 J/mol
Explanation:
Data provided:
Enthalpy of the pure liquid at 75° C = 100 J/mol
Enthalpy of the pure vapor at 75° C = 1000 J/mol
Now,
the heat of vaporization is the the change in enthalpy from the liquid state to the vapor stage.
Thus, mathematically,
The heat of vaporization at 75° C
= Enthalpy of the pure vapor at 75° C - Enthalpy of the pure liquid at 75° C
on substituting the values, we get
The heat of vaporization at 75° C = 1000 J/mol - 100 J/mol
or
The heat of vaporization at 75° C = 900 J/mol
Answer:- B. Solvent molecules surround solute ions.
Explanations:- When an ionic solute that has positive and negative ions is dissolved in a solvent like water then the solute ions are surrounded by the water molecules in a way so that the highly electron negative oxygen atom of water is towards the positively charged ion of the solute and less electron negative which is hydrogen atom that has partial positive charge, surrounds the negatively charged ion of the solute.
Due to these forces made by the solvent molecules, the solute is broken into the ions and get dissolved in solvent.
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Answer:
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Explanation:
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