Respuesta :
Answer:
The standard enthalpy is -247KJ/mol.
Explanation:
The balanced equation of the reaction is :
Zn(s) + 2HBr(aq) ---> ZnBr2(aq) + H2(g)
Number of moles can be calculated by the formula:
[tex]No. of moles=\frac{{given mass}}{molecular mass}[/tex]
No. of moles of zinc = [tex]\frac{2.50}{65.88}[/tex]
No. of moles of zinc = 0.0382 moles.
No. of moles of HBr = [tex]\text{No. of mole}=molarity\times \text{volume of solution}[/tex]
No. of moles of HBr = 2.00×0.100
= 0.200
Here, the limiting reagent is Zinc because every mole of zinc used in the reaction twice of the moles of HBr are needed. HBr is present in high amounts as compared with Zinc.
Heat absorption can be calculated by:
Heat absorption= Total heat capacity × Temperature
= 448×21.1
=9452 J.
Standard enthalpy can be calculated by:
Standard enthalpy = [tex]\frac{Heat absorption}{No. of moles of Zn}[/tex]
=[tex]\frac{9452}{0.0382}[/tex]
=247.
The standard enthalpy of reaction is -247 KJ/mol as the heat has been given off in the reaction.
The standard enthalpy of the reaction using the data. Zn(s)+2HBr(aq)⟶ZnBr2(aq)+H2(g) is:
- -247KJ/mol.
Standard enthalpy is the rate of change of enthalpy with the emergence of one mole of the composites of its elements.
Furthermore, in order to balance the equation, we would have to combine the powdered zinc and the hydrobromic acid which will give us:
- Zn(s) + 2HBr(aq) ---> ZnBr2(aq) + H2(g)
Additionally, to calculate the number of moles, we would use the formula:
Number of moles= mass/molecular mass
Listing out the values of each property
Number of moles of zinc= 0.0382 moles
Number of moles of HBr= molarity * volume of solution
=0.200 moles
Heat absorption= Total heat capacity * Temperature
448 * 21.1
=9452 J
Therefore, to calculate the standard enthalpy, we would get:
Heat absorption/no of moles of zinc
This would give us 9452J/0.0382= 247 Kj/mol
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