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Questions and Answers
What defines a pure substance?
What defines a pure substance?
- It is a single type of particle. (correct)
- It can be separated into other kinds of matter.
- It is a mixture of different substances.
- It consists of two or more types of particles.
Which of the following is an example of a homogeneous mixture?
Which of the following is an example of a homogeneous mixture?
- Salad
- Oil and water
- Sugar dissolved in water (correct)
- Sand and salt
What term is used for mixtures that have physically distinct parts?
What term is used for mixtures that have physically distinct parts?
- Homogeneous mixtures
- Compounds
- Elements
- Heterogeneous mixtures (correct)
Which of the following statements about mixtures is false?
Which of the following statements about mixtures is false?
What can be used to separate dissolved substances from water?
What can be used to separate dissolved substances from water?
If two groups have different amounts of copper sulfate, what does this indicate?
If two groups have different amounts of copper sulfate, what does this indicate?
What type of mixture is sea water classified as?
What type of mixture is sea water classified as?
When two substances are combined but do not dissolve, the result is typically what type of mixture?
When two substances are combined but do not dissolve, the result is typically what type of mixture?
Which property indicates that a material can be drawn into wires?
Which property indicates that a material can be drawn into wires?
What is a characteristic feature of non-metals compared to metals?
What is a characteristic feature of non-metals compared to metals?
Which of the following is an example of a metal?
Which of the following is an example of a metal?
What is the state of mercury at room temperature?
What is the state of mercury at room temperature?
Which elements are considered metalloids?
Which elements are considered metalloids?
What happens when you mix and heat iron filings with sulphur powder?
What happens when you mix and heat iron filings with sulphur powder?
Which of the following describes the texture and color of non-metals?
Which of the following describes the texture and color of non-metals?
What is a property that non-metals do not exhibit?
What is a property that non-metals do not exhibit?
What type of change occurs when camphor is separated from salt?
What type of change occurs when camphor is separated from salt?
Which of the following is a chemical change?
Which of the following is a chemical change?
What is the technique used to separate salt from sea-water?
What is the technique used to separate salt from sea-water?
Which of the following physical properties can be observed without changing the composition of matter?
Which of the following physical properties can be observed without changing the composition of matter?
During the burning of a candle, what type of changes take place?
During the burning of a candle, what type of changes take place?
What happens during the process of boiling water to form steam?
What happens during the process of boiling water to form steam?
What is the best description for changes like cutting of trees and dissolving sugar in water?
What is the best description for changes like cutting of trees and dissolving sugar in water?
Which of these changes involves a change in chemical properties?
Which of these changes involves a change in chemical properties?
What characterizes a solution?
What characterizes a solution?
Which of the following is an example of a heterogeneous mixture?
Which of the following is an example of a heterogeneous mixture?
What is an example of a solid solution?
What is an example of a solid solution?
What happens to the particles in a solution?
What happens to the particles in a solution?
Which method can be used to determine if a mixture is heterogeneous?
Which method can be used to determine if a mixture is heterogeneous?
What is the phase of the particles in a solution like lemonade?
What is the phase of the particles in a solution like lemonade?
How do you identify a substance in the context of mixtures?
How do you identify a substance in the context of mixtures?
In solution science, what does homogeneity refer to?
In solution science, what does homogeneity refer to?
What mass of potassium nitrate is needed to produce a saturated solution in 50 grams of water at 313 K?
What mass of potassium nitrate is needed to produce a saturated solution in 50 grams of water at 313 K?
What would happen to the solubility of potassium chloride as the solution cools from 353 K to room temperature?
What would happen to the solubility of potassium chloride as the solution cools from 353 K to room temperature?
At 293 K, which salt has the highest solubility?
At 293 K, which salt has the highest solubility?
Which of the following best describes what happens to the solubility of salts when temperature increases?
Which of the following best describes what happens to the solubility of salts when temperature increases?
What is a saturated solution?
What is a saturated solution?
Which of the following options is an example of a heterogeneous mixture?
Which of the following options is an example of a heterogeneous mixture?
How would you confirm that a colorless liquid is pure water?
How would you confirm that a colorless liquid is pure water?
Which of the following materials is categorized as a pure substance?
Which of the following materials is categorized as a pure substance?
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Study Notes
Pure Substances and Mixtures
- A pure substance consists of only one type of particle and cannot be physically separated.
- Examples include distilled water and crystalline compounds like copper sulfate.
- Mixtures are combinations of two or more pure substances and can be either homogeneous or heterogeneous.
Homogeneous vs. Heterogeneous Mixtures
- Homogeneous Mixtures: Have a uniform composition, the components are indistinguishable. Examples include sugar dissolved in water and saltwater.
- Heterogeneous Mixtures: Contain physically distinct parts and have non-uniform compositions. Examples include sand in water and salad.
Solutions
- A solution is a specific type of homogeneous mixture where a solute is dissolved in a solvent (e.g., sugar in water).
- Solutions can be liquids, solids (alloys), or gases (air) and exhibit uniform properties throughout.
Physical and Chemical Changes
- Physical Changes: Changes that do not alter the chemical composition, such as melting butter or boiling water.
- Chemical Changes: Involve a change in chemical composition and properties, resulting in new substances (e.g., rusting of iron, burning of wood).
Properties of Metals and Non-Metals
- Metals: Typically shiny, malleable, ductile, and good conductors of heat and electricity. Examples include iron and copper.
- Non-Metals: Generally dull, brittle, poor conductors. Examples include sulfur, phosphorus, and noble gases like argon.
- Metalloids: Exhibit properties of both metals and non-metals (e.g., silicon, boron).
Solubility and Temperature
- Solubility is the ability of a substance to dissolve in a solvent at a given temperature, typically expressed in grams of solute per 100 grams of solvent.
- Solubility often increases with temperature for many salts; potassium nitrate shows significant increase at higher temperatures.
Key Concepts
- Saturated Solution: A solution that cannot dissolve any more solute at a given temperature.
- Colloids: Mixtures where tiny particles are dispersed in another substance but do not settle out (e.g., milk).
- Suspensions: Mixtures where particles are suspended in a liquid but can settle out over time (e.g., muddy water).
Experiments and Observations
- Light beam experiments can demonstrate the transparency of solutions.
- Comparing the color intensity of solutions reveals variability even among homogeneous mixtures.
- Observations can lead to distinguishing between homogeneous and heterogeneous mixtures through physical properties.
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