Question

1. which type of change can be more easily reversed: chemical or physical? please explain in detail with an example of each. 6. identify the following statements about phosphorus as physical properties or chemical properties. briefly explain your choice. the first one is done for you. a. pure phosphorus is never found as an element, it is found in compounds in nature. chemical property: because phosphorous reacted to make a compound. b. phosphorus melts at the temperature of 44.1 °c. c. phosphorus can be stored safely under water. d. phosphorus dissolves in carbon disulfide liquid. e. phosphorus is a soft solid at room temperature. f. the density of phosphorus is 1.8 g/ml. g. the mass of a piece of phosphorus is 29.3 grams h. phosphorus reacts with fluorine to produce the compound phosphorus trifluoride. i. phosphorus can be either red or white as an element. 7. new terms: intensive properties (ip) do not change with the amount of matter present, while extensive properties (ep) do change with the amount of matter present. use this information to identify the properties of phosphorous in question #6 as intensive or extensive. a. ip intensive property. b. c. d. e. f. g. h. 8. which is better to use to distinguish one substance from another, intensive or extensive properties? explain why.

Explanation:

Question 5

Physical changes can be more easily reversed. In a physical change, the substance's chemical composition remains the same. For example, melting ice (solid - water) into liquid water is a physical change. By cooling the liquid water, it can be frozen back into ice. In a chemical change, a new substance is formed with a different chemical composition. For example, burning wood is a chemical change. The wood reacts with oxygen to form carbon - dioxide, water vapor and ash, and it is not possible to turn the products back into wood easily.

Question 6

• b. Physical Property: Melting point is a physical property as it describes a change in the state of matter (from solid to liquid) without changing the chemical composition of phosphorus.
• c. Chemical Property: Storing phosphorus under water is related to its reactivity with air (oxygen), a chemical reaction to prevent it from reacting with air.
• d. Physical Property: Dissolving in carbon - disulfide is a physical change as no new chemical substance is formed.
• e. Physical Property: Describing the state (soft solid) at room temperature is a physical property.
• f. Physical Property: Density is a physical property that can be measured without changing the chemical nature of the substance.
• g. Extensive Property: Mass depends on the amount of matter present, so it is an extensive property.
• h. Chemical Property: Reacting with fluorine to form a new compound (phosphorus trifluoride) is a chemical reaction.
• i. Physical Property: Color is a physical property that can be observed without changing the chemical composition of phosphorus.

Question 7

• b. IP: Melting point is an intensive property as it does not depend on the amount of phosphorus.
• c. IP: The ability to be stored safely under water is related to the chemical nature of phosphorus and not the amount, so it can be considered an intensive property in this context.
• d. IP: Solubility in carbon - disulfide is an intensive property as it does not change with the amount of phosphorus.
• e. IP: State at room temperature is an intensive property.
• f. IP: Density is an intensive property.
• g. EP: Mass is an extensive property as it depends on the amount of phosphorus.
• h. IP: Reactivity with fluorine is a chemical property and does not depend on the amount of phosphorus.
• i. IP: Color is an intensive property.

Question 8

Intensive properties are better to distinguish one substance from another. Intensive properties do not change with the amount of matter present, so they are characteristic of the substance itself. For example, density, melting point and color are unique for different substances and can be used to identify them, while extensive properties like mass or volume change with the amount of the substance and are not as useful for identification.

Answer:

Question 5

Physical changes can be more easily reversed. Example of physical change: melting ice; Example of chemical change: burning wood.

Question 6

• b. Physical Property: Describes state - change without chemical change.
• c. Chemical Property: Related to reactivity with air.
• d. Physical Property: No new chemical substance formed.
• e. Physical Property: Describes state at room temperature.
• f. Physical Property: Measured without chemical change.
• g. Extensive Property: Depends on amount of matter.
• h. Chemical Property: Forms new compound.
• i. Physical Property: Observed without chemical change.

Question 7

• b. IP
• c. IP
• d. IP
• e. IP
• f. IP
• g. EP
• h. IP
• i. IP

Question 8

Intensive properties. They are characteristic of the substance and do not depend on the amount of matter.