Question

A student added 10 g (0.25 mol) of sodium hydroxide to 40 cm3 of water to make a concentrated solution. All the sodium hydroxide dissolved. He measured the maximum temperature rise. He suggested that these results would give an accurate value for the standard enthalpy change of solution. Give two reasons why he is incorrect.

 

Answer 1

1st reason: 

 

The enthalpy of solution is how much hotness developed or consumed by the solution when the solute is broken down in the dissolvable at consistent strain. The standard enthalpy of the solution is the one when 1 mole of the solution is estimated under standard tension of 1 atm, and it is communicated in kJ/mol.

 

2nd reason: 

 

The standard enthalpy change of solution is the enthalpy change when 1 mole of the solute breaks up in the dissolvable under standard tension of 1 atm to give a solution of boundless weakening.

 

In the given issue, it says that 10g of NaOH broke up in 40 mL of water. This won\'t give a precise incentive for the standard enthalpy change of the arrangement on the grounds that the understudy utilized just under 1 mole of NaOH however we require 1 mole of NaOH to get ∆Hsol. This is the principal reason. The subsequent explanation is that when the enthalpy change of the arrangement occur, a boundless weaken arrangement is acquired and the temperature wouldn\'t rise. In this issue, it says that there is the greatest temperature rise. These are the two motivations behind why the understudy is inaccurate or student is incorrect.

In the given issue, it says that 10g of NaOH broke up in 40 mL of water.