Zinc metal reacts with hydrochloric acid according to this balanced equation. Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)?

2017-10-25 10:19 am
更新1:

When 0.116 g of Zn(s) is combined with enough HCl to make 54.8 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 21.8 ∘C to 24.6 ∘C. Find ΔHrxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/g⋅∘C as the specific heat capacity.) THANK YOU!

回答 (2)

2017-10-25 10:30 am
Amount of heat evolved in experiment
= Amount of heat to raise the temperature of water
= m c ΔT
= [(54.8 mL) × (1.0 g/mL)] × (4.18 J/g°C) × [(24.6 - 21.8)°C]
= 641 J

Molar mass of Zn = 65.4 g/mol
No. of moles of Zn
= (0.116 g) / (65.4 g/mol)
= 0.00177 mol

Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g) …… ΔHrxn

ΔHrxn
= (641 J) / (0.00177 mol Zn)
= 362000 J/mol Zn
= 362 kJ/mol Zn
2019-03-22 3:25 pm
-362kJ/mol Zn


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