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In a coffee-cup calorimeter, 0.00500 mol of mg is reacted with enough hno3 to produce 100.0 ml of solution. the reaction is shown below: mg (s) + 2 hno3 (aq) → mg(no3)2 (aq) + h2 (g) the temperature of the solution rose from 25.0°c to 30.5°c. find δhrxn for the reaction as written. assume that the density of the solution if 1.00 g/ml and specific heat is 4.18 j/g · °c.

Respuesta :

The given reaction is:

Mg(s) + 2HNO3 (aq) → Mg(NO3)2(aq) + H2(g)

The heat lost is given as:

q = mc(T2-T1) = 0.00500 mol * 12 g.mol-1 * 4.18 J/gC (30.5-25)C = 1.379 J

The volume of solution = 100 ml

Density = 1 g/ml

Mass of Mg(NO3)2 solution = 100 g

Molar mass of Mg(NO3)2 = 148 g/mol

# moles Mg(NO3)2 = 100/148 = 0.6756 moles

ΔH(rxn) = 1.379 J/0.6756 moles = 2.041 J/mol

Answer: the correct answer is -179 kJ/mol

Explanation:

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