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Questions and Answers
What distinguishes a pure substance from a mixture?
What distinguishes a pure substance from a mixture?
A pure substance consists of only one type of particle, whereas a mixture is composed of two or more pure substances that are not chemically bonded.
How does chromatography separate components of a mixture?
How does chromatography separate components of a mixture?
Chromatography separates components based on differences in polarity, causing substances to travel at different rates on a medium.
What are the implications of the Law of Constant Composition for chemical compounds?
What are the implications of the Law of Constant Composition for chemical compounds?
The Law of Constant Composition states that a given compound always contains the same elements in the same fixed ratio, regardless of its source.
Explain how the physical property of density can be used to separate mixtures.
Explain how the physical property of density can be used to separate mixtures.
What rule applies when performing addition with significant figures?
What rule applies when performing addition with significant figures?
Flashcards
Volume
Volume
The amount of space a substance takes up.
Mixture
Mixture
A combination of two or more pure substances that are not chemically bonded.
Element
Element
A substance that cannot be broken down into simpler substances by ordinary chemical means.
Distillation
Distillation
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Chemical Property
Chemical Property
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Study Notes
Matter and Mixtures
- Matter has mass and volume.
- Matter is categorized as either a pure substance or a mixture.
- Pure substances are further classified as elements or compounds.
- A mixture is a combination of two or more pure substances that are not chemically bonded.
Methods of Separating Mixtures
- Filtration: Separates mixtures based on particle size.
- Distillation: Separates mixtures based on boiling point differences.
- Centrifuging: Separates mixtures based on density differences.
- Magnetism: Separates mixtures containing iron (Fe), cobalt (Co), or manganese (Mn).
- Chromatography: Separates components of a mixture based on differences in polarity.
Physical Properties
- Physical properties describe a substance without changing its identity.
- Examples of physical properties include:
- Taste
- Smell
- Molar mass
- Density
- Melting point
- Boiling point
- Freezing point
Chemical Properties
- Chemical properties describe how a substance reacts with other substances.
- Examples of chemical properties include:
- Reactivity with oxygen (O₂)
- Reactivity with acids
- Reactivity with bases
- Burning
Density
- Density is calculated as mass divided by volume (D=m/v).
Compounds
- A compound is formed when two or more different elements are chemically bonded.
- The Law of Constant Composition states that a given compound always contains the same elements in the same proportion by mass.
Diatomic Elements
- Seven elements exist as diatomic molecules: Br₂, I₂, N₂, Cl₂, H₂, O₂, F₂
Mixtures
- A heterogeneous mixture is not uniform in composition throughout.
- A homogeneous mixture is uniform in composition throughout.
Prefixes
- Kilo (k): 10³
- Centi (c): 10⁻²
- Milli (m): 10⁻³
Significant Figures (Sig Figs)
- Addition/Subtraction Rule: The result can only have as many decimal places as the measurement with the fewest decimal places.
- Multiplication/Division Rule: The result can only have as many significant figures as the measurement with the fewest significant figures. .
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