Nitrogen in air reacts at high temperature to form no2 according to the reaction:

n2 + 2 o2 ? 2 no2

draw structures for the reactants and products indicating the number of single, double and triple bonds.

determine the ? h for the reaction using table 7.1.

[hint: one no2 has one [n-o] bond and one [n=o] bond]

a.

+115 kcal

b.

-78 kcal

c.

+78 kcal

d.

+7 kcal

e.

none of these

The correct answer is option E.

Explanation:

Structures for the reactants and products are given in an aimage ;

Number of double bonds in oxygen gas molecule = 1

Number of double bonds in nitro dioxide gas molecule = 1

Number of single bond in in nitro dioxide gas molecule = 1

Number of triple bonds in nitrogen gas molecule = 1

(pure element)

(pure element )

The enthalpy of the given reaction is 15.86 kcal.

The empirical formula of X is  C8H8O3

Explanation:

Step 1: Data given

Suppose the mass = 100.00 gram

A compound contains:

⇒ 63.2 % carbon = 63.2 grams

⇒ 5.31 % hydrogen = 5.31 grams

⇒ 31.6 % oxygen = 31.6 grams

Molar mass of carbon = 12.01 g/mol

Molar mass of hydrogen = 1.01 g/mol

Molar mass of oxygen = 16 g/mol

Step 2: Calculate number of moles

(63.2 g C) / (12.01 g/mol) =  5.26 mol C arbon

(5.32 g H) / (1.01 g/mol) = 5.27 mol H ydrogen

(31.6 g O) / (16.00 g/mol) = 1.975 mol O

Step 3: Calculate mol ratio

Divide by the smallest number of moles:

C: 5.26/ 1.975 = 2.66

H: 5.27 /1.975 = 2.67

O: 1.975/1.975 = 1

To achieve integer coefficients, we multiply by 3:

The empirical formula of X is  C8H8O3