What is a pure substance?

A substance in which there is only one type of particle.

List three properties that can be used to classify elements.

Boiling point, melting point, density.

Which category of element would be the least appropriate choice for making a container that can be dropped without shattering? Explain your answer.

Nonmetals, they would break.

Identify the group of elements that have each of the following properties: a. good conductors of electric current. b. brittle and non malleable. c. shiny. d. poor conductors of thermal energy.

a. metals and metalloids.
b. nonmetals.
c. metals and some metalloids.
d. nonmetals.

How are metalloids different from metals?

Some are dull.

What is a compound?

A pure substance made of two or more elements that are chemically combined.

What type of change is needed to break down a compound?

A chemical change.

A jar contains samples of the elements carbon and oxygen. Does the jar contain a compound? Explain.

No, the two elements are no chemically combined.

How are compounds and elements alike? How do they differ?

They are both pure substances. An element cannot be broken down into simpler substances.

What are two ways to break down a compound?

1. Heating
2. Electrolysis

How do the properties of sodium chloride compare with the properties of sodium and of chlorine?

Sodium chloride is a white solid that dissolves in water and is safe to eat. Chlorine is a greenish-yellowish gas.

What is the difference between an element and a compound?

Elements cannot be separated into simpler substances, but a compound can by chemical means.

A light green powder is heated in a test tube. A gas is given off, while the solid becomes black. In which classification of matter does the green powder belong? Explain your reasoning.

Compound, it changed in color and gave off a gas which means it went through a chemical change.

Explain why compounds are considered pure substances.

They are composed of only one type of particle and those particles are chemically combined.

If a spoonful of salt is mixed in a glass of water, the salt is the _______.

Solute

______ are solid solutions of metals or nonmetals dissolved in metals.

Alloys

A colloid has properties of both solutions and ______.

Suspensions

A ______ is composed of particles of two or more substances that are distributed evenly amongst one another.

Solution

Which of the following is NOT a solution: air in a scuba tank, muddy water, a soft drink, or salt water?

Muddy Water

When solid iodine is dissolved in alcohol, which is the solute? Which is the solvent?

Iodine is the solute, alcohol is the solvent.

Why might a lake in a tropical area contain more dissolved minerals than a lake in Main?

The temperature of the tropical lake is probably higher, and many minerals are more soluble in warmer water than in colder water.

When nail polish is dissolved in acetone, which substance is the solute and which is the solvent?

The solute is the polish, and the acetone is the solvent.

Describe a procedure to separate a mixture of salt, finely ground pepper, and pebbles.

Pass the mixture through a screen that allows the salt and pepper to pass through but traps the pebbles. Mix the salt and pepper with water to dissolve the salt. Filter it to get the pepper.

To keep the "fizz" in carbonated beverages after they have been opened, should you store them in a refrigerator or in a cabinet? Explain.

Fridge because gases are more soluble at a lower temperature.

What is the concentration of a solution prepared by mixing 50 g of salt with 200 mL of water?

50/200= 0.25 g/mL

How many grams of sugar must be dissolved in 150 mL of water to make a solution with a concentration of 0.6 g/mL?

150*0.6= 90 g

Nearly all of the fresh water in Saudi Arabia is produced by removing salt from sea water. One method involves distillation. Explain how sea water could be purified by distillation, and tell whether it is a chemical or physical process.

Salt water is a mixture, so its components can be separated by physical methods.