When 10.00 g of phosphorus is burned in o2(g) to form p4o10(s), enough heat is generated to raise the temperature of 2990 g of water from 18.0 ∘c to 38.0 ∘c. part a calculate the heat of formation of p4o10(s) under these conditions?

-3.10 × 10⁶ J/mol

Explanation:

The heat (Qw) required to raise the temperature of the water can be calculated using the following expression.

Qw = c . m . ΔT

where,

c: specific heat capacity

m: mass

ΔT: change in the temperature

Qw = (4.186 J/g.°C) . 2990 g . (38.0°C - 18.0°C) = 2.50 × 10⁵ J

According to the law of conservation of energy, the sum of the heat released from the formation of P₄O₁₀ and the heat absorbed by the water is zero.

Qw + Qf = 0

Qf = -Qw = -2.50 × 10⁵ J

Let's consider the formation of P₄O₁₀.

4 P(s) + 5 O₂(g) → P₄O₁₀(s)

The heat of formation must be expressed per mole of P₄O₁₀. -2.50 × 10⁵ J is the heat released when 10.00 g of P react. Let's consider the following conversion factors:

The heat of formation of P₄O₁₀ is: