To make polyethylene, its monomer ethylene must first be synthesized from fossil fuels. Petroleum and natural gas are broken into smaller molecules through a process called steam cracking. During this process, fossil fuels are heated to temperatures up to 900°C. Large carbon-based molecules are broken apart, or "cracked," to produce small molecules like ethane. Once ethane is made, it decomposes due to the high temperatures to make hydrogen gas and ethylene.

Question

Select the true statements.
A. the synthesis of ethlylene is a chemical change
B. steam cracking breaks smaller molecules into larger molecules
C. high temperatures are required to make ethylene
D.hydrogen gas reacts with ethane to make ethylene

Answer 1

The true statements are:

A. the synthesis of ethylene is a chemical change - True. The transformation of ethane into ethylene involves a chemical reaction, which is indeed a chemical change.

C. high temperatures are required to make ethylene - True. The process of steam cracking requires high temperatures (up to 900°C) to effectively break down larger molecules into ethylene and other products.

The false statements are:

B. steam cracking breaks smaller molecules into larger molecules - False. Steam cracking involves breaking larger carbon-based molecules into smaller ones, not the other way around.

D. hydrogen gas reacts with ethane to make ethylene - False. Ethylene is produced from ethane by breaking it down through high temperatures, rather than being produced from a reaction between hydrogen gas and ethane.

So, the true statements are A and C.