When Zn metal is dissolved in hydrochloric acid at a constant pressure, the temperature of the solution increases from 275.0 K to 285.0 K. Is the reaction exothermic or endothermic and what is the sign on qrxn
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The temperature of the solution increases from 275.0 K to 285.0 K, indicating that heat is being released into the solution. Show more…
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A $2.50$ -gram sample of powdered zinc is added to $100.0 \mathrm{~mL}$ of a $2.0$ -M aqueous solution of hydrochloric acid in a calorimeter with a total heat capacity of $481 \mathrm{~J} \cdot \mathrm{K}^{-1} .$ The observed increase in temperature is $12.2 \mathrm{~K}$ at a constant pressure of one bar. Using these data, calculate the value of $\Delta H_{\mathrm{rxn}}^{\circ}$ for the equation, $$ \mathrm{Zn}(s)+2 \mathrm{HCl}(a q) \rightarrow \mathrm{ZnCl}_{2}(a q)+\mathrm{H}_{2}(g) $$ which describes the reaction that occurs when the two substances are mixed.
Zinc metal reacts with hydrochloric acid according to the balanced equation: $$ \mathrm{Zn}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{ZnCl}_{2}(a q)+\mathrm{H}_{2}(g) $$ When $0.103 \mathrm{~g}$ of $\mathrm{Zn}(s)$ is combined with enough $\mathrm{HCl}$ to make $50.0 \mathrm{~mL}$ of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from $22.5{ }^{\circ} \mathrm{C}$ to $23.7{ }^{\circ} \mathrm{C}$. Find $\Delta H_{\mathrm{rx}}$ for this reaction as written. (Use $1.0 \mathrm{~g} / \mathrm{mL}$ for the density of the solution and $4.18 \mathrm{~J} / \mathrm{g} \cdot{ }^{\circ} \mathrm{C}$ as the specific heat capacity.)
Find ΔHrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/g·°C as the specific heat capacity.) Zinc metal reacts with hydrochloric acid according to the following balanced equation. Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) When 0.114 g of Zn(s) is combined with enough HCl to make 51.9 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.3 °C to 24.7 °C. Part A Find ΔHrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/g·°C as the specific heat capacity.)
Adi S.
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