Question

Consider the reaction: HCl + NaOH --> NaCl + H2O

Given the information below:

HCl solution 22degreesC; NaOH solution 22C; Final temperature: 26.1C

A.Calculate the amount of heat evolved when 15 mL of 1.0 M HCl was mixed with 35 mL of 1.0 M NaOH.
I used the formula Q = mC(Tf-Ti) and got -858 J, or -0.858 kJ.

B. Calculate delta H per mole of water formed from this data, in both Joules and kJ/mole.

Part (B) is where I'm confused. I'm pretty sure I did part (A) right but I just don't even know where to start with (B).

Answer 1

The delta H is for the formation of H2O (on the product side). You need to calculate the moles of H2O formed.

1) calculate limiting reactant
2) calculate moles of H2O formed
3) calculate j/mol or kj/mol => j/mol H2O

Answer 2

I think I got the moles of water already: 50 mL * 1L / 1000 mL * 1 mol / 1 L = .05 mol H2O

Answer 3

Also, it asks for kJ/mol and then just Joules-- not divided by moles. I don't get how both of those can be calculated.

Answer 4

B. Calculate delta H per mole of water formed from this data, in both Joules and kJ/mole.

I'm understanding the question to be, calculate j/mol and kJ/mol.