A common laboratory reaction is the neutralization of an acid with a base. When

Question

A common laboratory reaction is the neutralization of an acid with a base. When 50.0 mL of 0.500 M HCl at 25.0°C is added to 50.0 mL of 0.500 M NaOH at 25.0°C in a coffee cup calorimeter, the temperature of the mixture rises to 28.2°C. Assume the mixture has a specific heat capacity of 4.18 J/(g.K) and the densities of all solutions are 1.00 g/mL

a.) Calculate the qrxn

B.) Calculate deltaH rxn per mole of acid

C.) When this reaction is repeated with 50.0 mL of 2.0 M HCI at 25.0°C, the temperature of the mixture also increases to 28.2°C. Explain

Explanation / Answer

Mass of HCl= 50ml* 1 g/ml = 50gms ( since the density is 1 )

Mass of NaOH= 50 mn*1 g/ml =50 gm

Total mass =50+50 =100 gms

difference in temperature = 28.2-25 3.2 deg.c

Heat capacity = 4.18 J/g.K

delH of reaction = mass* heat capacity * difference in temperature = 100* 4.18* 3.2 =1337.6 joules= 1.3376 Kj

b) moles of HCl in 50ml of 0.5 M= 0.5*50/1000=0.025 moles

0.025 moles releasea heat to the tune of 1.3376 Kj

1 moles releases 1.3376/0.025=53.504 Kj/mol =Q

At constant pressure Q=delH= 53.504 Kj/mol

c) The solution is assumed to be dilute and hence the mass of 50ml 0f 2.0 M HCl remains the same. This leads to the rise in temperaute being same with 50ml of 0.5M HCl as well as 2M HCl. But however, since there is change in number of moesl delH of reaction changes

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.