Answer:
The standard enthalpy of formation of HgO is -90.7 kJ/mol.
Explanation:
The reaction between Hg and oxygen is as follows.
From the given,
Molar mass of HgO = 216.59 g/mol
Mass of HgO decomposed = 18.5 g
Amount of heat absorbed = 7.75 kJ
From the reaction,
The standard enthalpy of formation = 
During the decomposition of 1 mol of HgO , 90.7 kJ of energy absorbed.
For the formation of 1 mol of HgO , 90.7 kJ of energy is release
Therefore, the enthalpy of formation of mercury(II)Oxide is -90.7 kJ/mol
Answer:
Temperature is a common type of controlled variable. If a temperature is held constant during an experiment, it is controlled. Other examples of controlled variables could be an amount of light, using the same type of glassware, constant humidity, or duration of an experiment.
Explanation:
Atomic mass of sodium is 22.9 g/mol
atomic mass of chloride is 35.45 g/mol
sodium chloride is 22.99 + 35.45= 58.44 g/mol
The value of ΔG° at this temperature is -18034.18 J/mol
Calculation,
Given information
formation constant (Kf)= 1.7 × 
Universal gas constant (R) = 8.314 J/K• mol
Temperature = 25° C = 25 °C + 273 = 300 K
Formula used:
ΔG° = -RT㏑Kf
By putting the valur of R,T, Kf we get the value of ΔG°
ΔG° = - 8.314 J/K• mol×300K㏑ 1.7 ×
ΔG° = -2494.2㏑ 1.7 × = -18034.18 J/mol
So, change in standard Gibbs's free energy is -18034.18 J/mol
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Answer:
<u>Oxidation state of Mn = +4</u>
Explanation:
Atomic mass of Mn = 55g/mol
From Faraday's law of electrolysis,
Electrochemical equivalent = 
i.e Z = 
= 
= 0.0001424 g/C
But Equivalent weight, E = atomic mass ÷ valency = Z × 96,485
⇒ 
= 0.0001424 × 96,485
<u>∴ Valency of Mn = +4</u>
