Question

A chemist measures the energy change AH during the following reaction: CzHg(9)+502(9) — 3C0 (9)+4H20(1) AH=-2220. kJ Use the information to answer the following questions. This reaction is... X10 Suppose 50.4 g of C,H, react. endothermic. exothermic. Yes, absorbed. Yes, released. TO No. Will any heat be released or absorbed? If you said heat will be released or absorbed in the second part of this question, calculate how much heat will be released or absorbed. Be sure your answer has the correct number of significant digits.

Answer 1

Consider a given reaction, C₃H₈ (g) + 5 O ₂ (g) $\rightarrow$ 3 CO ₂ (g) + 4 H₂O (l)   $\Delta$ H = - 2220 kJ

The negative sign of $\Delta$ H indicates that heat is released in the reaction. We know that, reaction in which heat is released is called exothermic reaction. Hence, above reaction is exothermic reaction.

Molar mass of C₃H₈ = ( 3 $\times$ 12.01 ) + ( 8 $\times$ 1.0079) = 44.09 g / mol

From reaction, we get information that when 44.09 g of C₃H₈ reacts with oxygen gas , 2220 kJ heat is released .

$\therefore$ Heat released by the reaction of 50.4 g C₃H₈ with oxygen gas is 50.4 g ( 2220 kJ / 44.09 g ) = 2790.9 kJ

Answer should be rounded to 3 significant figures , because 50.4 contain three significant figures. Hence, answer is 2790 kJ or 2.79 $\times$ 10 ³

ANSWER :

The reaction is	o Endothermic $\bullet$ Exothermic
Suppose 50.4 g of C3H8 react. Will any heat be released or absorbed ?	o Yes , absorbed. $\bullet$ Yes, released o No
If you said heat is released or absorbed in the second part of this question . calculate how much heat is released or absorbed.	2790 kJ