What is the enthalpy of neutralisation for a reaction between HCl and NaOH?

  • Thread starter repugno
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In summary, the conversation discusses the calculation of enthalpy of neutralisation using the example of adding HCL and NaOH solutions to a cup and measuring the temperature rise. The formula used is heat absorbed by solution = mass * specific heat capacity * temperature change. The limiting reagent is not specified. The enthalpy of neutralisation for strong acids and bases is a constant at 57.1 kJ/mol. The conversation also mentions calculating the moles of HCL and NaOH using their respective molarities and finding the rise in temperature with the given heat value.
  • #1
repugno
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Hello all,

I don't quite understand how to calculate the enthalpy of neutralisation. Example, if I add [itex]50cm^3[/itex] of a [itex]1.0 mol dm^-3[/itex] solution of HCL to a polystyrene cup. And then add [itex]50cm^3[/itex] of a [itex]1.1 mol dm^-3[/itex] of NaOH to the same cup, we'll get a reaction with a temperature rise. The temperature rise can be noted and a calculation can be made to find the enthalpy of neutralisation.

So, assuming no heat is lost to the suroundings and the specific heat capacity of the solution is the same as that of water, then

Heat absorbed by solution = m * c * t
= 100 * 4.2 * 6.5
= 2730J

This is the part i don't understand, do I divide this figure with the moles of HCL in the solution or the moles of NaOH?

Any help would be much appreciated. Thank you
 
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  • #2
Write out a balanced equation and find the limiting reagent from the info provided. Use this mol value.

It does not matter the way you state it, just kJ/mol will do as long as you associated with the particular reaction.

Hope this answers your question.
 
  • #3
calculate number of moles for HCL through given data ... ( u know molarity...find moles) and same for NaOH ...

Since the first one is strong acid ..the other is strong base...so their Enthalpy Of Nuetralization will be 57.1 KJ/mol which is constant for strong acids and bases.


calculate ...RISE IN TEMP ...cuz u got the net heat released...
 

1. What is enthalpy of neutralisation?

The enthalpy of neutralisation is the amount of heat released or absorbed when an acid and a base react to form 1 mole of water under standard conditions.

2. How is enthalpy of neutralisation measured?

The enthalpy of neutralisation is measured using a calorimeter, which is a device that measures the heat changes in a chemical reaction. The change in temperature of the reaction mixture is used to calculate the enthalpy of neutralisation.

3. What factors affect the enthalpy of neutralisation?

The enthalpy of neutralisation is affected by the strength of the acid and base, as well as the concentrations of the reactants. The nature of the solvents used and the temperature also play a role in determining the enthalpy of neutralisation.

4. How does enthalpy of neutralisation relate to the pH scale?

The enthalpy of neutralisation is directly related to the pH scale. A strong acid and a strong base will have a higher enthalpy of neutralisation, resulting in a more neutral pH. On the other hand, a weak acid and a weak base will have a lower enthalpy of neutralisation, resulting in a more acidic or basic pH.

5. Why is enthalpy of neutralisation important?

The enthalpy of neutralisation is important in understanding the energetics of acid-base reactions. It can also be used to determine the strength of an acid or base, as well as the concentrations of the reactants. Additionally, the enthalpy of neutralisation plays a crucial role in many chemical processes and reactions in industries such as pharmaceuticals, food and beverage, and agriculture.

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