Section Review 3

Is CH4 an element, a compound, a homogeneous mixture, or heterogeneous mixture?

A compound

What is CH2O?

A compound

What is distilled water?

A compound

Why is a monatomic compound nonsensical?

A compound must be composed of more than one type of atom, so it cannot be monatomic.

What is concrete?

A heterogeneous mixture

What is salt water?

A homogeneous mixture

Imagine dissolving a spoonful of sugar in a glass of water. Is the sugar-water combination classified as a compound or mixture? Explain your answer.

A mixture; they are not chemically combined. Each material keeps its own properties and identity.

How are atoms and molecules related?

A molecule consists of one or more atoms.

Define the term compound

A substance made up of atoms of two or more different elements joined by chemical bonds.

What is S8?

An element

How does an element differ from a compound?

An element is made up of one type of atom, but a compound must be made up of atoms of two or more different elements.

Four different containers are labeled C+O2, CO, CO2 and Co. Based on the labels, classify each as an element, a compound, a homogeneous mixture, or heterogeneous mixture. Explain your reasoning.

C+O2 is a heterogeneous mixture because the materials are a solid and gas. CO is a compound. CO2 is a compound. Co is an element.

What are two differences between compounds and mixtures?

Compounds have properties that differ from the properties of their components, but mixtures have properties that often reflect the properties of the components that make up the mixture. A compound has a definite composition, so the components must be present in exact ratios. Mixtures have varying components.

How could you decide whether a ring has 24-karat gold or 14-karat gold without damaging the ring?

Determine its density.

What are the two types of pure substances?

Elements and compounds

How is a homogeneous mixture different from a heterogeneous mixture?

In a homogeneous mixture, the components are distributed evenly throughout, so the properties of the mixture are the same throughout. In a heterogeneous mixture, the components are not evenly disturbed, so there are regions of the mixture with different properties.

Compare the composition of sucrose purified from sugar cane with the composition of sucrose purified from sugar beets.

The compositions are identical. Sucrose is a compound, so it must have a definite composition no matter what its source is.

After a mixture of iron and sulfur are heated and then cooled, a magnet no longer attracts the iron. How would you classify the resulting material? Explain your answer.

The material is a compound of the iron and sulfur. The material is not attracted to a magnet, so it has different properties than the original materials had.

What is the smallest number of elements needed to make a compound?

Two