A) a calorimeter contains 33.0mL of water at 13.0 Celcius. when 2.50 g of X ( a

Question

A) a calorimeter contains 33.0mL of water at 13.0 Celcius. when 2.50 g of X ( a substance with a molar mass of 82.0g/mol) is added, it dissolves via the reaction

X(s)+H2O(L)--->X(aq)

and the temperature of the solution increases to 26.5 Celcius. Calculate the enthalpy change, DELTA H, for this reaction per mole of X

Assume that the specific heat of the resulting solution is equal to that of water [4.18 J/(g * C)], that density of water is 1.00 g/mL and that no heat is lost to the calorimeter itself, nor to the surroundings. Express the change in enthalpy in kilojoules per mole to three significant figues

i put -61.1 kj/mol but its still wrong

B) Consider the reaction

C12H22O11(s) + 12O2(g)--->12CO2(g)+11H2O(l)

in which 10.0 g of sucrose, C12H22O11, was burned in a bomb calorimeter with a heat capacity of 7.50 kJ/ Celcious. The temperature increase inside the calorimeter was found to be 22.0 Celcius. Calculate the change in internal energy, Delta E, for this reaction per mole of sucrose.

Express the change in internal energy in kilojoules per mole to three significant figures

i put 5.412 kj/mol but its still wrong

somebody help me with this!

Explanation / Answer

since delta H/delta T = Cp
delta H= Cp * delta T
Cp(Molar Specific Heat) = M (Molar Mass) * Specific Heat Capacity(cp)

Cp= 67 * 4.18= 280.06

delta H= 280.06 * 15 = 4200.9 = 4.2 kJ mole^-1

This is the Enthalpy Change When 1 Mole Reacts.
When 1.79 * 10^-2 will react
delta H = 1.79 * 10^-2 * 4.2
= 7.518 * 10^-2 kJ

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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