The following question appears on a quiz: "you fill a tank with gas at 60°c to 100 kpa and seal it. you decrease the temperature to 10°c but keep the volume constant. what happens to the pressure? " a student answers that the new pressure will be 17 kpa. which of the following explanations is true?

the student did not solve for the correct parameter, and the answer should be 50 kpa.

the student did not solve for the correct parameter, and the answer should be 600 kpa.

the student did not work with absolute temperatures, and the answer should be 85 kpa.

the student did not work with absolute temperatures, and the answer should be 888 kpa.

The student did not work with absolute temperatures, and the answer should be 85 kPa.

Explanation:

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

R is the general gas constant,

T is the temperature of the gas in K.

P₁T₂ = P₂T₁

P₁ = 100.0 kPa, T₁ = 60.0°C + 273 = 333.0 K.

P₂ = ??? kPa, T₂ = 10.0°C + 273 = 283.0 K.

∴ P₂ = P₁T₂/T₁ = (100.0 kPa)(283.0 K)/(333.0 K) = 84.98 kPa ≅ 85.0 kPa.

The student did not work with absolute temperatures, and the answer should be 85 kPa.

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.