Quizs on Pure Substances and Compounds

Definition of a pure substance

• A pure substance contains only one type of substance.

• A pure substance can be a mixture of different elements.

• A pure substance is always a solid at room temperature.

• A pure substance can be easily separated into its components.

How are pure substances identified?

• Pure substances have a specific melting and boiling point.

• Pure substances can be identified by their color and odor.

• Pure substances always exist in a solid state.

• Pure substances can be mixed with any other substance without changing their properties.

Test for Oxygen gas

• Relights a glowing splint

• Produces a pop sound

• Turns lime water milky

• Changes color to blue

How are impure substances identified?

• They have a fixed melting and boiling point.

• Melting and boiling happen over a range of temperatures for an impure substance.

• They dissolve completely in water.

• They emit a distinct color when heated.

One way to test if water is pure

• Pure water boils at exactly 100°C.

• Pure water has a pH of 7.

• Pure water is colorless and odorless.

• Pure water freezes at 0°C.

Test for Carbon Dioxide gas

• Turns limewater cloudy white

• Turns water blue

• Produces a sweet smell

• Releases bubbles in vinegar

Are paints formulations?

• Yes

• No

• Sometimes

• Only in certain cases

Definition of a compound

• A compound is a substance formed when two or more elements are chemically combined.

• A compound is a mixture of two or more substances that retain their individual properties.

• A compound is a single element that cannot be broken down into simpler substances.

• A compound is a solution where one substance is dissolved in another.

Definition of an element

• A substance made of one type of atom only.

• A mixture of different types of atoms.

• A compound formed by chemical reactions.

• A solution that contains multiple elements.

Test for Hydrogen gas

• A lit splint produces a squeaky pop

• A colorless gas that burns with a blue flame

• A gas that turns limewater milky

• A gas that has a pungent odor