Thermodynamics ...

Reaction of silica with mineral acids may be given as:
$$Si{ O }_{ 2 }+4HF\longrightarrow Si{ F }_{ 4 }+2{ H }_{ 2 }O;\Delta H=-10.17kcal$$
$$Si{ O }_{ 2 }+4HCl\longrightarrow Si{ Cl }_{ 4 }+2{ H }_{ 2 }O;\Delta H=+36.7kcalHCl$$
Which among the following is correct?

Which one of the following ores is best concentrated by froth floatation method?

Predict the sign of $$\Delta S$$ for each of the following processes, which occur at constant temperature:
$$I$$. The volume of $$2$$ mol of $${O}_{2}(g)$$ increases from $$44L$$ to $$54L$$
$$II$$. The pressure of $$2$$ mil of $${O}_{2}(g)$$ increases from $$1$$ atm to $$1.2$$ atm.

From the following data of heats of combustion, find the heat of formation of $${ CH }_{ 3 }OH(l)$$:
$${ CH }_{ 3 }OH(l)+\cfrac { 3 }{ 2 } { O }_{ 2 }(g)\longrightarrow C{ O }_{ 2 }(g)+2{ H }_{ 2 }O(l);\Delta H=-726kJ$$
$$C(s)+{ O }_{ 2 }(g)\longrightarrow C{ O }_{ 2 }(g);\Delta H=-394kJ$$
$${ H }_{ 2 }(g)+\cfrac { 1 }{ 2 } { O }_{ 2 }(g)\longrightarrow { H }_{ 2 }O(l);\Delta H=-286kJ$$

The free energy for a reaction having $$\Delta H=31400\ cal,\Delta S=32\ cal\ { K }^{ -1 }{mol}^{-1}$$ at $${1000}^{o}C$$ is:

The most abundant element in the universe is thought to be:

Calculate the heat of formation of methane, given that
heat of formation of water $$=-286kJ\quad { mol }^{ -1 }$$
heat of combustion of methane $$=-890kJ\quad { mol }^{ -1 }$$
heat of combustion of carbon $$=-393.5kJ\quad { mol }^{ -1 }$$

When a substance A reacts with water it produces a combustible gas B and a solution of substance C in water. When another substance D reacts with this solution of C, it also produces the same gas B on warming but D can produce gas B on reaction with dilute sulphuric acid at room temperature. A imparts a deep golden yellow colour to a smokeless flame of Bunsen burner. A, B, C and D respectively are:

Calculate the standard free energy change for the combustion of glucose at $$298\ K$$, using the given data.
$${ C }_{ 6 }{ H }_{ 12 }{ O }_{ 6 }+6{ O }_{ 2 }(g)\longrightarrow 6{ CO }_{ 2 }(g)+6{H}_{2}O$$
$$\Delta { H }^{ o }=-2820\ kJ\ { mol }^{ -1 };\Delta { S }^{ o }=210\ J{ K }^{ -1 }{ mol }^{ -1 }$$

For the reaction,
$${ Br }_{ 2 }(l)+{ Cl }_{ 2 }(g)\longrightarrow 2BrCl(g)$$
$$\Delta H=29.37kJ\quad { mol }^{ -1 };\Delta S=104J\quad { mol }^{ -1 }$$. Find the temperature above which the reaction would become spontaneous.