Question

Consider the combustion reaction below. If 100.0 g of sulfur trioxide are produced from this reaction, what is the heat of the reaction? 2802(g) + O2(g) - 2503 (9) AHrxn - 242.2 kJ O a. 151.4 k) b.-151.4 k) (c. 302.8 kg d.-302.8 k) QUESTION 8 Consider the following reaction: 2NO(g) + O268) - 2N026) Allrxn--116 kJ/mol AHNO2 is 33.2 kJ/mol and Ho2 is 0 kJ/mol. What is the AHNO

Answer 1

First question

When 2 moles of SO₃ is produced, the heat of reaction = 242.2 kJ

Converting moles to mass using :

Mass ( in g) = Number of moles x molar mass ( in g/mol).

So, molar mass of SO₃ = 80 g/mol.

Thus, mass of SO₃ = 2 moles x 80 g/mol = 160 g

So, 160 g of SO₃ has heat of 242.2 kJ

So, 100 g will have heat of reaction as = = + 151.4 kJ

242.2 k) x 100 g 160 g

Question 8.

ΔHrxn = ΔH of products – ΔH of reactants

So, -116 kJ/mol = [ (2mol)( ΔH of NO₂) ] – [ ( 2mol)( ΔH of NO) + (1mol)( ΔH of O2)]

Or, -116 kJ/mol = 2(33.3) – 2(ΔH_NO)

Solving, ΔH_NO = 91.2 kJ/mol