10 Questions
What is an example of a physical change that cannot readily be undone by physical means?
Mixing of different metal elements to form an alloy
How are mixtures of substances that are not soluble usually separated?
By physical sieving or settlement
What effect do crystals in metals have on the physical properties of the metal?
They have a major effect on the strength and ductility of the metal
Which process results in substances such as iodine and carbon dioxide going directly from solid to gas?
Sublimation
What can be separated by fractional distillation?
Mixtures of volatile liquids
Which of the following best describes a physical change?
A change that affects the form of a substance without altering its chemical composition
What is an example of a physical change?
Dissolving salt in water
Which property would be considered a physical property?
Color of a substance
What distinguishes a physical change from a chemical change?
Physical changes alter the physical properties of a substance, while chemical changes alter its chemical composition
Which process exemplifies a physical change?
Boiling water to produce steam
Study Notes
Physical Changes
- An example of a physical change that cannot readily be undone by physical means is melting of glass.
Separating Mixtures
- Mixtures of substances that are not soluble are usually separated by physical methods, such as filtration or centrifugation.
Crystals in Metals
- Crystals in metals have a significant impact on the physical properties of the metal, such as strength and ductility.
Phase Changes
- Sublimation is the process that results in substances such as iodine and carbon dioxide going directly from solid to gas.
- This process occurs when the intermolecular forces between molecules are weak, allowing them to change directly from solid to gas.
Separation Techniques
- Fractional distillation is a method used to separate a mixture of two or more substances with different boiling points.
Defining Physical Changes
- A physical change is best described as a change in which a substance changes its state, but its chemical composition remains the same.
- An example of a physical change is the melting of ice, where the solid (ice) changes to a liquid (water).
- Physical properties, such as color, shape, and state, are characteristics that can be observed or measured without changing the chemical composition of a substance.
Distinguishing Physical and Chemical Changes
- A physical change is distinguished from a chemical change by the fact that the chemical composition of the substance remains the same.
- A process that exemplifies a physical change is the dissolving of sugar in water, where the sugar changes its state from solid to solution, but its chemical composition remains the same.
Test your knowledge about physical changes, which affect the form of a substance without changing its chemical composition. Explore how physical changes are used to separate mixtures and understand the contrast with chemical changes.
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