Identify each enthalpy change by name and classify each change as exothermic or endothermic.
a)1 mol C3H8 (l) ==> 1 mol C3H8 (g)
b)1 mol Hg (l) ==> 1 mol Hg (s)
c)1 mol NH3 (g) ==> 1 mol NH3 (l)
d)1 mol NaCl(s) + 3.88kJ/mol ==> 1 mol NaCl (aq)
e)1 mol NaCL (s) ==> 1 mol NaCl (l)
a. Vaporization; endothermic
b. Solidification; exothermic
c. Condensation; exothermic
d. Dissolution; endothermic.
e. Melting; endothermic.
so nobody know the answer?
a) Enthalpy change: vaporization
Classification: endothermic (because it goes from a liquid to a gas, which requires energy)
b) Enthalpy change: solidification
Classification: exothermic (because it goes from a liquid to a solid, which releases energy)
c) Enthalpy change: condensation
Classification: exothermic (because it goes from a gas to a liquid, which releases energy)
d) Enthalpy change: dissolving
Classification: endothermic (because it requires energy to dissolve the solid in water)
e) Enthalpy change: fusion
Classification: endothermic (because it goes from a solid to a liquid, which requires energy)
a) The enthalpy change is called vaporization (or evaporation), and it is an endothermic process since energy is absorbed to convert the liquid to gas.
b) The enthalpy change is called solidification (or freezing), and it is an exothermic process since energy is released to convert the liquid to solid.
c) The enthalpy change is called condensation, and it is an exothermic process since energy is released to convert the gas to liquid.
d) The enthalpy change is called dissolution (or hydration), and it is an endothermic process since energy is absorbed (indicated by the positive value) to dissolve the solid in water and form an aqueous solution.
e) The enthalpy change is called fusion (or melting), and it is an endothermic process since energy is absorbed to convert the solid to liquid.
To identify each enthalpy change by name and classify them as exothermic or endothermic, we need to consider the direction of heat flow. If heat is released by the system, the process is exothermic. If heat is absorbed by the system, the process is endothermic.
a) 1 mol C3H8(l) ==> 1 mol C3H8(g)
This process is called vaporization. Since heat is absorbed to convert a liquid to a gas, it is endothermic.
b) 1 mol Hg(l) ==> 1 mol Hg(s)
This process is called freezing or solidification. Heat is released to convert a liquid into a solid, so it is exothermic.
c) 1 mol NH3(g) ==> 1 mol NH3(l)
This process is called condensation. Heat is released as a gas changes to a liquid, making it exothermic.
d) 1 mol NaCl(s) + 3.88 kJ/mol ==> 1 mol NaCl(aq)
In this process, solid NaCl dissolves in water to form an aqueous solution. The energy change (3.88 kJ/mol) corresponds to the enthalpy of solution. If 3.88 kJ of heat is absorbed by the system, it is endothermic.
e) 1 mol NaCl(s) ==> 1 mol NaCl(l)
This process involves the melting of solid NaCl. Heat is absorbed to convert a solid to a liquid, so it is endothermic.
In summary:
a) Vaporization: Endothermic
b) Freezing/Solidification: Exothermic
c) Condensation: Exothermic
d) Dissolution/Enthalpy of Solution: Endothermic
e) Melting: Endothermic