Iteemm 8 YD Manganese reacts with hydrochloric acid to produce manganese(II) chl

Question

Iteemm 8 YD

Manganese reacts with hydrochloric acid to produce manganese(II) chloride and hydrogen gas.
Mn(s)+2HCl(aq) MnCl2(aq)+H2(g)

When 0.645 g Mn is combined with enough hydrochloric acid to make 100.0 mL of solution in a coffee-cup calorimeter, all of the Mn reacts, raising the temperature of the solution from 23.8 C to 28.4 C.
Find Hrxn for the reaction as written. (Assume that the specific heat capacity of the solution is 4.18 J/gC and the density is 1.00 g/mL.)

Express your answer using three significant figures.

Hrxn =________ kJ

Explanation / Answer

solution mass= volume x density = 100ml x 1g/ml = 100 g

temp change = 28.4-23.8 = 4.6 C

heat asborbed by solution = specifc heat x mass of solution x temp change

           = 4.18 x 100 x 4.6 = 1922.8 = 1.9228 KJ

dleta H reaction in KJ = 1.92

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