Question

1. Instant cold packs used to ice athletic injuries on the field contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following reaction:

NH4NO3 (s) à NH4 (aq) + NO3- (aq)

In order to measure the enthalpy change for this reaction, 1.25 g of NH4NO3 was dissolved in 25.0 g of water. The initial temperature was 25.8 ° C and the final temperature (after all solid dissolved) was 21.9°C. (Specific heat of water, c = 4.18 J/g °C).

(a) Calculate qrxn. (20 points)

(b) Calculate qH2O. (20 points)

(c) Calculate (20 points)

(d) Is the Reaction endothermic or exothermic? (20 points)

2. Given this reaction: CO (g) + ½ O2 (g) à CO2 (g) ΔH = -282 kJ, what is the ΔHrxn for the following reaction:

2 CO2 (g) à 2 CO (g) + O2 (g) ΔHrxn = ??​​ (20 points)

q = mCΔT​qrxn = - qH2O ​​ = qrxn

just skip c then thank you

Answer 1

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