Calorimetry Question

[Sanguinne]

Each experiment involved adding 50.0ml of 2.0M acid to 50.0ml of 2.0 NaOH solution and using the stirrer to agitate the liquid. The highest temperature reached was recorded to determiner the temperature change for the neturalisation reaction:
H₃O⁺ + OH^- --> 2H₂O
a) i) When 2M HCL was used in the experiment, te temperature increased by 10.1C. Calculate the heat of neutralisation for this reaction. You may assume that the specific heat capcity of the solution is the same as that of water.

[Yacoubb]

Each experiment involved adding 50.0ml of 2.0M acid to 50.0ml of 2.0 NaOH solution and using the stirrer to agitate the liquid. The highest temperature reached was recorded to determiner the temperature change for the neturalisation reaction:
H₃O⁺ + OH^- --> 2H₂O
a) i) When 2M HCL was used in the experiment, te temperature increased by 10.1C. Calculate the heat of neutralisation for this reaction. You may assume that the specific heat capcity of the solution is the same as that of water.

I'm probably not right but I'll take a jab. If I'm wrong could someone please let me know? Thanks!

Energy = m * c * change in temperature
= 50 * 4.18 * 10.1
= 2110.9J
= 2.1109kJ

n(HCl) = n(H3O+)
n(H2O) = n(H3O+) * 2 = 0.1 * 2 = 0.2 mol

Therefore:

(2.1109) / (0.2/2) = - 21.1 kJ/mol

[jgoudie]

Only issue with this is your SHC calculation.  We are using 50ml of HCl and 50ml of NaOH.  Thus our total mass of water would be 100, so double your answer.

I'm probably not right but I'll take a jab. If I'm wrong could someone please let me know? Thanks!

Energy = m * c * change in temperature
= 50 * 4.18 * 10.1
= 2110.9J
= 2.1109kJ

n(HCl) = n(H3O+)
n(H2O) = n(H3O+) * 2 = 0.1 * 2 = 0.2 mol

Therefore:

(2.1109) / (0.2/2) = - 21.1 kJ/mol

[Yacoubb]

Only issue with this is your SHC calculation.  We are using 50ml of HCl and 50ml of NaOH.  Thus our total mass of water would be 100, so double your answer.

Ah yes got it! Thank you

[Sanguinne]

wait if we need to work out the mass in grams, wouldnt we need to convert using the density of the acids rather than
using the property of water where 1g = 1ml?

[jgoudie]

Yes we should, but as no information is given about the density of 2M HCl or 2M NaOH, we need make the assumption it will 1g/ml, the same as water.  The question lead us to this also by state we assume the SHC is that of water.

wait if we need to work out the mass in grams, wouldnt we need to convert using the density of the acids rather than
using the property of water where 1g = 1ml?