Question

1. Titanium reacts with iodine to form titanium(III) iodide, emitting heat. 2Ti(s)+3I2(g)→2TiI3(s)ΔHorxn = -839 kJ

partA)Determine the masses of titanium and iodine that react if 1.70×103kJ of heat is emitted by the reaction.

Express your answer using three significant figures.

part B)Zinc metal reacts with hydrochloric acid according to the following balanced equation.

Zn(s)+2HCl(aq)→ZnCl2(aq)+H2(g)

When 0.114 g of Zn(s) is combined with enough HCl to make 50.1 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 21.8 ∘C to 23.9 ∘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.)

Answer 1

1)

2Ti (s) + 3I2 (g)   ------------------> 2TiI3 (s)        ΔHorxn = -839 kJ

for 2 mol of Ti --------------- ΔHorxn = -839 kJ

   ?? mol of Ti --------------- ΔHorxn = - 1.70 x 10^3 kJ

moles of Ti = 4.05

moles of Ti = mass / molar mass of Ti

4.05 = mass / 47.87

mass of Ti = 194 g

for 3 mol of I2 --------------- ΔHorxn = -839 kJ

   ?? mol of I2 --------------- ΔHorxn = - 1.70 x 10^3 kJ

moles of I2 = 6.08

moles of I2 = mass / molar mass of I2

6.08 = mass / 253.81

mass of I2 = 1543 g

2)

heat energy Q = m Cp dT

                        = 50.1 x 4.18 x (21.8 - 23.9)

                        = - 439.78 J

moles of Zn = mass / molar mass

                     = 0.114 / 65.38

                     = 0.0017

for 0.0017 mol ----------- - 439.78 J heat

for 1 mol           ---------------- ??

ΔHrxn = - 439.78 / 0.0017

            = - 258694 J / mol

           = - 258.7 kJ/mol

ΔHrxn     = - 258.7 kJ/mol