General Chemistry I (Exam
1) – Pitt 2026 | Study
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Updated 2026 Questions and Answers
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, What is an example of a chemical change in matter? When iron rusts, the iron atoms combine with oxygen atoms to form a different
chemical substance, the compound iron oxide, so its chemical identity
(composition) is changed.
What three compositions can Matter be classified by? Elements, Compounds, Mixtures
What is a pure substance? Something made up of only one component, and its composition is invariant (it
does not vary from one sample to another).
What are examples of pure substances? Helium, water, and sodium chloride; helium is made up of ONLY helium atoms,
water is made up of ONLY water molecules, and sodium chloride is made up
ONLY of sodium chloride units.
What is a mixture? Something composed of two or more components in proportions that can vary
from one sample to another.
What is an example of a mixture? Sweetened tea, composed primarily of BOTH water molecules and sugar
molecules; it is not made up ONLY of one or the other.
Pure substances can be classified into what two types? Elements, Compounds
What is an element? A substance that cannot be chemically broken down into simpler substances
(composed of a single type of atom, like Helium).
What is a compound? A substance composed of two or more elements in a fixed, definite proportion,
like hydrogen and oxygen comprising water.
Mixtures can be categorized into what two types? Heterogeneous, Homogeneous
What does it mean if a mixture is heterogeneous? The composition varies from one region of the mixture to another, like different
letters spread out in an alphabet soup; there are multiple substances whose
presence can be seen.
What does it mean if a mixture is homogeneous? The composition stays the same (uniform) throughout all regions of the mixture,
like how sweet tea should taste the same throughout a whole glass; made of
multiple substances but appears to be one substance.
What are qualitative observations? Observations that are descriptive in nature, not involving numbers.
What are quantitative observations? Observations that involve measurements (numbers).
1) – Pitt 2026 | Study
Guide, Questions &
Review
|Graded A+ | Guaranteed
success|
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
, What is an example of a chemical change in matter? When iron rusts, the iron atoms combine with oxygen atoms to form a different
chemical substance, the compound iron oxide, so its chemical identity
(composition) is changed.
What three compositions can Matter be classified by? Elements, Compounds, Mixtures
What is a pure substance? Something made up of only one component, and its composition is invariant (it
does not vary from one sample to another).
What are examples of pure substances? Helium, water, and sodium chloride; helium is made up of ONLY helium atoms,
water is made up of ONLY water molecules, and sodium chloride is made up
ONLY of sodium chloride units.
What is a mixture? Something composed of two or more components in proportions that can vary
from one sample to another.
What is an example of a mixture? Sweetened tea, composed primarily of BOTH water molecules and sugar
molecules; it is not made up ONLY of one or the other.
Pure substances can be classified into what two types? Elements, Compounds
What is an element? A substance that cannot be chemically broken down into simpler substances
(composed of a single type of atom, like Helium).
What is a compound? A substance composed of two or more elements in a fixed, definite proportion,
like hydrogen and oxygen comprising water.
Mixtures can be categorized into what two types? Heterogeneous, Homogeneous
What does it mean if a mixture is heterogeneous? The composition varies from one region of the mixture to another, like different
letters spread out in an alphabet soup; there are multiple substances whose
presence can be seen.
What does it mean if a mixture is homogeneous? The composition stays the same (uniform) throughout all regions of the mixture,
like how sweet tea should taste the same throughout a whole glass; made of
multiple substances but appears to be one substance.
What are qualitative observations? Observations that are descriptive in nature, not involving numbers.
What are quantitative observations? Observations that involve measurements (numbers).
