Question

Which of the following materials is a substance?
air
gasoline
stainless steel
silver

Answer 1

Silver

Answer 2

what kind of substance? a pure substance? that's silver. a homogeneous substance? that's all of them. be more specific

Answer 3

First, know the definition of a substance.
Chemical substances are any material(s) (in any state - solid, liquid or gas) that have a DEFINATE chemical COMPOSITION. All samples of the substance has the same composition.

Chemical substances can therefore be either a pure chemical element or a pure chemical compound.

Based on your answer choices, you can quickly identify silver as an element off the periodic table and based on the definition you know that is that answer. You are looking to identify pure substance (element or compound) vs. Mixture (heterogenous or homogeneous).

(X) air = nitrogen, oxygen, traces of argon, carbon dioxide, other gasses—all not chemically bonded to each other. VARIES in composition.

(X)gasoline = mixture of hydrocarbons. VARIES in composition.

(X) stainless steel = mixture of metal alloys – nickel, iron, chromium, manganese. VARIES in composition.

Answer 4

I've no idea what your instructor wants to hear, but a working chemist would call all of them "substances." A "substance" is just some reasonably uniform (on the macroscopic level) stuff out of which things can be made. Essentially, if it has a separate name -- air, wood, charcoal, steel, Styrofoam, glass, concrete, seawater -- then it's a substance, as far as the working chemist is concerned.

You can always make more precise distinctions if you want to. For example:

(1) Air is a solution -- a mixture homogenous right down to the atomic level -- of nitrogen, oxygen, argon, and a variety of trace gases like water vapor and CO2. Some of those constituents, like nitrogen and oxygen, are elements, while others, like water and carbon dioxide, are compounds. A compound is a substance made of other substances (elements), but which cannot be separated into its components without a chemical reaction. Air, for example, can be separated into its constituents by filtering, fractional condensation, centrifugation, and other means -- none of which involve a chemical reaction. But CO2 cannot be separated into carbon (C) and oxygen (O) without a chemical reaction. CO2 is a compound, air is a mixture.

(2) Gasoline is also a solution, of a number of different hydrocarbons, mostly alkanes with 6 to 9 carbons, but some alkenes, alkynes, and odds and ends. Almost all of the constituents of gasoline are compounds, and these compounds are almost all made of carbon and hydrogen, which are elements.

(3) Stainless steel is a solid solution, also called an alloy, of iron, carbon, and usuallly chromium and perhaps some vanadium. All of those are elements.

(4) Silver is an element. An element is a substance which cannot be separated, by a chemical reaction, into two or more other substances.

Answer 5

Kudos, Carl_Pham! :) Here is someone who knows their Chemistry!

Iloveyoubabyboy1996, if you are taking college chemistry, you will need to be able to analyze and identify substances this way. I am taking CHM 101 and this would be a dream question to have on the exam but it’s not what they throw at you. STUDY HARD!

Answer 6

Just to be clear, my answer response is based on presuming that the question is looking to identify a PURE SUBSTANCE (and I based that presumption on the answer choices). Answer choices = (1) pure substance vs. (3) mixtures.
Remember, a pure substance will have a definite composition. Mixtures (heterogeneous or homogenous) will VARY in composition.
Keep in mind that mixtures are made up of 2 or more substances [they are all substances like Carl_Pham and others say].