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When pure sulfuric acid is dissolved in water, heat is evolved. In a laboratory experiment to measure the molar heat of solution of sulfuric acid, the following procedure was followed. To a calorimeter containing 3.00 × 102 g of water at 20.00 °C, 10.65 g of H2SO4, also at 20.00 °C was added. The tempera­ture change, which was monitored by a digital thermometer with negligible heat capacity, ceased when it reached a temperature of 26.55 °C. If the specific heat of the mixture is 4.184 J g‑1 °C‑1, and the small heat capacity of the calorimeter is ignored, what is the heat evolved, per mole of sulfuric acid? Show an overview of your work.

Respuesta :

Answer: The amount of heat evolved per mole of sulfuric acid is 78104.7 Joules.

Explanation:

We are given:

Mass of water = [tex]3.00\times 10^2g=300g[/tex]

Mass of sulfuric acid = 10.65 g

To calculate the amount of heat evolved, we use the equation:

[tex]q=mc\Delta T[/tex]

where,

m = mass of water + sulfuric acid = [300 + 10.65] = 310.65 g

c = specific heat capacity of mixture = 4.184 J/g.°C

[tex]\Delta T[/tex] = change in temperature = [tex]T_2-T_1=26.55^oC-20^oC=6.55^oC[/tex]

Putting values in above equation, we get:

[tex]q=310.65g\times 4.184J/g.^oC\times 6.55^oC\\\\q=8513.42J[/tex]

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of sulfuric acid = 10.65 g

Molar mass of sulfuric acid = 98 g/mol

Putting values in above equation, we get:

[tex]\text{Moles of sulfuric acid}=\frac{10.65g}{98g/mol}=0.109mol[/tex]

Calculating the heat released per mole of sulfuric acid, we get:

[tex]q=\frac{\text{Heat eveolved}}{\text{Moles of sulfuric acid}}\\\\q=\frac{8513.42J}{0.109mol}=78104.7J[/tex]

Hence, the amount of heat evolved per mole of sulfuric acid is 78104.7 Joules.

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