Question

The overall reaction in a commercial heat pack can be represented as How much heat is released when 4.40 moles of iron are reacted with excess ? Heat = kJ How much heat is released when 1.00 mole of is produced? Heat = kJ How much heat is released when 1.60 g iron is reacted with excess ? Heat = kJ How much heat is released when 11.8 g and 1.20 g are reacted? Heat = kJ

Answer 1

Answer:

Explanation:

The overall equation for this reaction can be represented as:$4 Fe(s) + 3 O_{2(g) } \to 2Fe_2O_{3(s)} \ \ \ \ \Delta H = -1652 \ kJ$

The first question says:

How much heat is released when 4.40 moles of iron is reacted with excess O₂?

Suppose 1652 kJ of heat is being emitted into the surroundings when four(4) moles of Fe reacted with O₂, therefore;

4.40 moles of Fe reacts with:

$=\dfrac{4.40 \ moles \times 1652 \ kJ}{4 \ moles}$

= 1817.2 kJ of heat will be produced.

The second question says:

How much heat is released when 1.00 mole of $Fe_2O_3$ is produced?

Given that 1652 kJ of heat is being emitted into the surroundings when two(2) moles of $Fe_2O_3$ is produced, therefore;

1.00 moles of $Fe_2O_3$ reacts with:

$=\dfrac{1.00 \ moles \times 1652 \ kJ}{2 \ moles}$

= 826 kJ of heat will be produced.

To the third question; we have:

How much heat is released when 1.60 g iron is reacted with excess O₂?

We need to find the number of moles of iron first.

We know that number of moles = mass/molar mass

Thus, the molar mass of iron = 55.8 g/mol

number of moles of iron = (1.60g) / (55.8 g/mol)

number of moles of iron = 0.02867 mol

Thus; $\dfrac{0.02867\ mol \times 1652 \ kJ }{4 \ mol}$

= 11.84 kJ of heat is released.

The last question says:

How much heat is released when 11.8 g Fe and 1.20 g O₂ are reacted?

Again;

the number of moles of Fe = (11.8g) / (55.8 g/mol) = 0.2114 mole of Fe

Thus; $\dfrac{0.2114\ mol \times 1652 \ kJ }{4 \ mol}$

= 87.31 kJ of heat is released.

On the other hand,

the number of moles of O₂ = (1.20g) / (32 g/mol) = 0.0375 mol of O₂

Thus; $\dfrac{0.0375\ mol \times 1652 \ kJ }{3 \ mol}$

= 20.65 kJ of heat is released

Therefore, when these two(2) reactants reacted with each other, it is just the smaller amount of heat that would be released because oxygen tends to be the limiting reactant.