For which of the following processes does the entropy of the system increase? (a) the ripening of a banana, (b) dissolution of sugar in a cup of hot coffee, (c) the reaction of nitrogen atoms to form N2 molecules at 25 ∘C and 1 atm, (d) lightning, (e) formation of CH4 and O2 molecules from CO2 and H2O at room temperature and 1 atm of pressure?

Explanation:

A. The ripening of a banana

Ripening of banana releases ethene is a gas which increases the entropy of the system.

B. Dissolution of sugar in a cup of hot coffee

Solid sugar will dissolve in aqueous medium to be liberate sugar molecules and is more distributed throughout the hot coffee, thus an increase in the entropy of the system.

C. The reaction of nitrogen atoms to form N2 molecules at 25 degree C and 1 atm. It takes two atoms to form 1 molecule of N2

A decrease in the number of the particles leads to a decrease in the entropy of the system.

D. Lightning

The process of lightning is from ions coming together to releases energy in the form of light. Thus the system has less energy leading to a decrease in the energy distribution and a decrease in the entropy of the system.

E. Formation of CH4 and O2

CO2 and H2O at room temperature and 1 atm of pressure is a gas while H2O exits as a liquid. When CH4 and O2 are formed, they will both be in the gas phase. Change of phase from Liquid to gas increases the entropy of the system.

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as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2