Josiah and Alicia have been excited all week because their science teacher has arranged for a guest speaker to present a lesson to their class on Friday. The guest speaker is a chemist. She spends part of the time explaining methane to the class. The chemist tells them methane is a flammable gas that can be formed when organic waste decomposes in a landfill. Methane is also present in natural gas, which is a fossil fuel. When methane reacts with oxygen gas, compounds called carbon dioxide and water are formed. The following models represent that process.

Question

a. Methane is flammable, but carbon dioxide is not. Does this make sense? Why or why not.

(1 point)
Responses

No, it doesn't make sense, because a physical change took place.
No, it doesn't make sense, because a physical change took place.

Yes, it makes sense, because a physical change took place.
Yes, it makes sense, because a physical change took place.

No, it doesn't make sense, because we expect products and reactants to have different properties.
No, it doesn't make sense, because we expect products and reactants to have different properties.

Yes, it makes sense, because we expect products and reactants to have different properties.
Yes, it makes sense, because we expect products and reactants to have different properties.
Question 2
b. How would you expect the boiling point of methane to compare with the boiling point of water?(1 point)
Responses

The boiling points would probably be the same, because products and reactants always have the same properties.
The boiling points would probably be the same, because products and reactants always have the same properties.

The boiling points would probably be different, because products and reactants usually have different properties.
The boiling points would probably be different, because products and reactants usually have different properties.

It is impossible to tell, because chemical reactions don't give us any clues about the properties of products compared to reactants.

Answer 1

Question 1 (a): For the question about the flammability of methane compared to carbon dioxide, the best response is:

Yes, it makes sense, because we expect products and reactants to have different properties.

This is correct because in a chemical reaction, the reactants (in this case, methane and oxygen) can have different properties than the products (carbon dioxide and water). Methane being flammable and carbon dioxide not being flammable demonstrates that the properties of substances can change during a chemical reaction.

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Question 2 (b): For the question about the boiling points of methane and water, the best response is:

The boiling points would probably be different, because products and reactants usually have different properties.

This response is appropriate because, in general, different substances have their own unique physical properties, including boiling points. Methane (boiling point of -161.5 °C) and water (boiling point of 100 °C) have significantly different boiling points due to their distinct molecular structures and interactions.