Question

Identify each of the following as a physical or chemical property: a. Gold is shiny. b. Gold melts at \(1064^{\circ} \mathrm{C}\). c. Gold is a good conductor of electricity. d. When gold reacts with yellow sulfur, a black sulfide compound forms.

Short answer

a. Physical, b. Physical, c. Physical, d. Chemical.

Step-by-step solution

Define physical property

A physical property is a characteristic of matter that can be observed or measured without changing its chemical identity.

Define chemical property

A chemical property describes a substance's ability to undergo a specific chemical change.

Identify shiny appearance of gold

Observing that 'Gold is shiny' is identifying a physical property since it can be observed without changing the substance.

Identify melting point of gold

The fact that 'Gold melts at 1064°C' is a physical property because it describes a physical change rather than a chemical change.

Identify electrical conductivity of gold

Identifying that 'Gold is a good conductor of electricity' is describing a physical property since it pertains to the physical behavior of a substance.

Identify reaction of gold with sulfur

The statement 'When gold reacts with yellow sulfur, a black sulfide compound forms' describes a chemical property because it involves a chemical reaction that changes the substance's chemical identity.

Key concepts

physical properties

Physical properties are characteristics of matter that can be observed or measured without changing the substance's chemical makeup. These include aspects such as color, density, and hardness. For example, the fact that gold is shiny explains its ability to reflect light. Observing the luster of gold doesn't alter its chemical structure.

Another example of gold's physical property is its melting point. Gold melts at a high temperature of 1064°C. This means it changes from a solid to a liquid at this specific temperature. However, during melting, the gold's chemical identity remains the same, making this a physical property.

The electrical conductivity of gold is also a physical property. Gold can efficiently conduct electricity, making it invaluable in electronics. This is due to the movement of electrons through the gold without any change in its chemical composition.

chemical properties

Chemical properties describe a substance's ability to undergo chemical reactions and transform into new substances. These properties are essential for predicting how elements will behave in different environments.

One common chemical property of gold is its reaction with sulfur. When gold reacts with yellow sulfur, it forms a black sulfide compound. This reaction changes the chemical identity of the gold, meaning it's no longer pure gold but a new compound. This process illustrates a chemical change.

Chemical properties of gold are crucial in various industries. For instance, in corrosion-resistant coatings and in chemical synthesis. Understanding these properties helps in utilizing gold for specific applications that require this kind of reactivity.

gold conductivity

Gold is an excellent conductor of electricity. This is a vital physical property that makes gold highly useful in the field of electronics. Electrical conductivity refers to the ability of a material to allow the flow of electric current.

Unlike other metals, gold does not tarnish or corrode over time, which ensures a stable and reliable connection. This makes gold ideal for components like connectors, switches, and relay contacts in high-end electronic devices.

The high conductivity of gold results from the free movement of electrons within its atomic structure. This property is measured in Siemens per meter (S/m). Pure gold has a conductivity of about 45.2 million S/m.

melting point

The melting point of a substance is the temperature at which it changes from a solid to a liquid. For gold, this critical temperature is 1064°C (1947°F). This is a distinct physical property useful in various applications.

Jewelry makers often rely on gold's melting point to craft intricate designs. Gold's relatively high melting point makes it suitable for alloys and applications requiring heat resistance.

This property is essential in industries such as aerospace and electronics, where high temperatures can be encountered. During the melting process, gold's structure does not change chemically, reinforcing that it is a physical property.