I just took my quiz and I'm confused because I got it wrong.
It asked which one is not a pure substance?
A. Ammonia
B. Steam
C. Gasoline
D. Iodine Crystals
I was running out of time and I chose Ammonia and I see it was a pure substance but I see the other three are too. I'm confused. Thank you
gasoline is a complex mixture of various hydrocarbons.
All the others consist of only one type of molecule or atom
Okay thank you so much. I was reading somewhere it was considered a pure substance
It is true that some math/chemistry problems involving gasoline will say assume gasoline is octane, C8H18; however, it really is a complex mixture of hydrocarbons. In fact the composition changes with the season and the altitude of the area in which it is sold/used.
I understand your confusion. The question you encountered during your quiz asked you to identify the substance that is not a pure substance. To determine the correct answer, we need to understand what pure substances are.
A pure substance is a type of matter that has a uniform and definite composition. It consists of only one type of element or compound. Pure substances cannot be separated into any other types of matter through physical means.
Now, let's analyze the given options:
A. Ammonia: Ammonia (NH3) is a compound, consisting of a combination of nitrogen and hydrogen atoms. Since it is a compound with a definite composition, it is considered a pure substance.
B. Steam: Steam is formed when water (H2O) undergoes a phase change from a liquid state to a gaseous state. As water is also a compound with a definite composition, steam is also considered a pure substance.
C. Gasoline: Gasoline is a mixture of various hydrocarbons. It is not a pure substance because it does not have a uniform and definite composition. It consists of different types of molecules, so it is not considered a pure substance.
D. Iodine Crystals: Iodine crystals are composed solely of iodine atoms (I2). Like ammonia and steam, iodine crystals are considered a pure substance since they are composed of only one type of element.
Based on this analysis, the correct answer is C. Gasoline, as it is not a pure substance due to its varying composition.
If you encounter similar questions in the future, remember to consider the nature of pure substances and their uniform composition to identify the correct answer.