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.

Question

Coleman Lyons

Chemistry

8 January, 14:53

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.

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Micah Werner · Answer 1

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