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Kryger [21]
2 years ago
14

The phase change between white tin and gray tin is difficult to observe directly. Both substances can be burned, however. From t

hese equations, calculate AHⓇ for the conversion of gray tin into white tin:
Sn(s, white) + O2(g) + SnO2(g) AH = -580.69 kJ
Sn(s, gray) + O2(g) + SnO2(g) AH° = -582.78 kJ
AH = _________ kJ
Chemistry
1 answer:
AleksandrR [38]2 years ago
8 0

Answer: Thus \Delta H for the conversion of gray tin to white tin is -20.9 kJ

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to this law, enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

The final reaction is

Sn(s, gray)\rightarrow Sn(s, white)  \Delta H=?

The intermediate balanced chemical reaction will be,

Sn(s, gray)+O_2(g)\rightarrow SnO_2(g)  \Delta H^0=-582.78kJ    (1)

Sn(s, white)+O_2(g)\rightarrow SnO_2(g)  \Delta H^0=-580.69kJ     (2)    

substarcting (2) form (1) we get

\Delta H=\Delta H_1-\Delta H_2

\Delta H=-582.78-(-580.69kJ)

\Delta H=-20.9kJ

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Kb means ebulloscopic constant (0,52 °C.kg/m .- a known value for water)

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This number means I have 0,432 moles of acetate sodium, my solute in 1kg of water, my solvent. But I don't have 1000 g (1kg) I only have 283 g so let's make the rule of three:

1000 g _____ 0,432 moles

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