Question

Consider the combustion of propane: A balloon is being inflated to its full extent by heating the air inside it. In the final stages of this process, the volume of the balloon changes from L to L by the addition of J energy as heat. Assume that all the heat comes from the combustion of propane. What mass of propane must be burned to furnish this amount of energy assuming the heat transfer process is 50.% efficient?

Answer 1

Answer:

5162.539 g

Explanation:

Let assume that the volume changes from $4.00 \times 10^6 \ L$ to $4.50 \times 10^6 \ L$.

And if the addition of energy as heat is $1.3 \times 10^8 \ J$

Then; we can say that the total heat that is taken by the ballon = $1.3 \times 10^8 \ J$

$= 1.3 \times 10^5 \ kJ$

The total heat supplied = total heat coming from the combustion of propane

∴

$= \dfrac{100}{50} \times 1.3 \times 10^5 \ kJ$

$= 2.6 \times 10^5 \ kJ$

$C_3 H_{8(g)} + 5O_{2(g)} \to #CO_{2(g)} + 4H_2O_{(l)} \ \ \Delta H = -2221 \ kJ$

If 2221 kJ is produced as a result of the combustion of 44.1 g $C_3H_{8(g)}$

Then;

$2.6 \times 10^5 kJ$ will produce $= \Big( \dfrac{44.1 \times 2.6 \times 10^5}{2221} \Big ) \ g$

= 5162.539 g

Thus, the mass of the propane that must be burned = 5162.539 g