Question

which of the following equations shows a chemical change? (1 point)
○ $c_{2}h_{5}oh(l)\to c_{2}h_{5}oh(g)$
○ $nh_{3}(g)\to nh_{3}(l)$
● $c_{3}h_{8}+5o_{2}\to 3co_{2}+4h_{2}o$
○ $h_{2}o(s)\to h_{2}o(g)$

Explanation:

A chemical change results in the formation of new substances. In the equation $C_{3}H_{8}+5O_{2}
ightarrow3CO_{2}+4H_{2}O$, propane ($C_{3}H_{8}$) reacts with oxygen ($O_{2}$) to form carbon - dioxide ($CO_{2}$) and water ($H_{2}O$), which are new substances. The other equations represent phase changes (liquid to gas, gas to liquid, solid to gas) which are physical changes, not chemical changes.

Answer:

$C_{3}H_{8}+5O_{2}
ightarrow3CO_{2}+4H_{2}O$