Page 110 - Innovator's Science-8

Magnesium (Mg) + Oxygen (O ) → Magnesium Oxide (MgO)
2
Substance Type Justification
Iron (Fe) Element A pure substance made of one kind of atom; it
cannot be broken down chemically.
Magnesium (Mg) Element Pure metal element; basic building block
of matter.
Oxygen (O2) Element Diatomic gas: a pure substance made of oxygen
atoms.
Water (H2O) Compound Chemically combined hydrogen and oxygen in a
fixed ratio.
Iron Oxide (Fe2O3) Compound Formed by a chemical reaction between iron and
oxygen, has new properties.
Magnesium Oxide (MgO) Compound Formed by a chemical reaction between
magnesium and oxygen.
Moist Air Mixture Contains gases like oxygen, nitrogen, water
vapor; not chemically combined.

6. Classify the following as elements, compounds, or mixtures in the Table.
Carbon dioxide, sand, seawater, magnesium oxide, muddy water, aluminum, gold, oxygen, rust, iron
sulfide, glucose, air, water, fruit juice, nitrogen, sodium chloride, sulfur, hydrogen, and baking soda.
Ans. Do yourself

7. What new substance is formed when a mixture of iron filings and sulfur powder is heated, and how is
it different from the original mixture? Also, write the word equa on for the reac on.
Ans. When iron filings and sulfur powder are heated, they react to form a new substance called ferrous
sulfide (FeS), also known as iron sulfide. This is a chemical change, and the resul ng compound has
different proper es from the original iron and sulfur. The word equa on for the reac on is:
Iron + Sulfur → Ferrous Sulfide.
Original Mixture
Iron filings and sulfur powder are physically mixed. They retain their individual proper es, and the
mixture can be separated by physical means like using a magnet to a ract the iron.
Ferrous Sulfide (FeS)
Hea ng the mixture causes a chemical reac on. Iron and sulfur combine to form a new substance,
ferrous sulfide. This is a compound, meaning the atoms are chemically bonded.
Difference in Proper es
Ferrous sulfide has its unique proper es that are dis nct from those of iron and sulfur. For example, it is a
black solid, whereas iron is typically gray, and sulfur is yellow. It is also not a racted to magnets like iron.
Word equa on
The word equa on for the reac on is Iron + Sulfur → Ferrous Sulfide

8. Is it possible for a substance to be classified as both an element and a compound? Explain why or why
not.
Ans. No, a substance cannot be classified as both an element and a compound. Elements are pure substances
that cannot be broken down into simpler substances by chemical means, while compounds are formed
when two or more different elements are chemically bonded together. The defining characteris c of a

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Science-8