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Sagot :
Answer:
-163kJ/mol
Explanations:
Given the reaction between the zinc metal reacts with HCl according to the balanced equation:
[tex]Zn+2\text{HCl}\rightarrow\text{ZnCl}_2+H_2[/tex]The required heat of reaction will be calculated using the formula below:
[tex]\triangle H_{\text{rxn}}=-\frac{Q}{n_{Zn}}[/tex]where:
• Q is the ,heat produced
,• nZn is the, number of moles that reacted
The formula for calculating the quantity of heat produced is expressed as:
[tex]Q=mc\triangle\theta[/tex]where:
• m is the ,mass, of the ,Zinc metal
,• c is the ,specific heat capacity, of zinc
,• △θ is th,e change in temperature
Get the mass of zinc
[tex]\begin{gathered} \text{mass}=\text{ }density\times\text{volume} \\ m=\rho\times v \end{gathered}[/tex]The quantity of heat becomes:
[tex]Q=\rho\cdot v\cdot C\triangle\theta[/tex]Substitute the given parameters to have:
[tex]\begin{gathered} Q=\frac{1.02\cancel{g}}{\cancel{mL}}\times50\cancel{mL}\times\frac{4.18J}{\cancel{g^oC^{}}}\times(23.7-22.5)\cancel{^oC} \\ Q=1.02\times50\times4.18\times1.2 \\ Q=255.8Joules \end{gathered}[/tex]Next is to get the number of moles of Zinc that reacted (nZn)
[tex]\begin{gathered} nZ_n=\frac{Mass}{\text{Molar mass}} \\ nZ_n=\frac{0.103g}{65.4g\text{/mol}} \\ nZ_n=0.00157mole \end{gathered}[/tex]Get the required heat of reaction of Zinc:
[tex]\begin{gathered} \triangle H_{\text{rxn}}=-\frac{Q}{nZ_n} \\ \triangle H_{\text{rxn}}=-\frac{255.8Joules}{0.00157moles} \\ \triangle H_{\text{rxn}}=-162,929.93J\text{/mol} \\ \triangle H_{\text{rxn}}\approx-163kJ\text{/mol} \end{gathered}[/tex]Hence the heat of the reaction of Zinc is approximately -163kJ/mol
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