Topic 4.4: Physical and Chemical Changes

Signs of Chemical Changes

Color Change

Temperature Change

Release of Light

Bubbling & Fizzing

Precipitate

New Smells

Observe at
least 2 Signs
to identify a

Chemical
Change!

Multiple Choice

When a drop of acid landed on the chemistry teacher's pants, a small hole appeared.

• Chemical Change

• Physical Change

Multiple Choice

Over time, solutions of iodine and water gradually lose color as the iodine evaporates.

• Chemical Change

• Physical Change

Multiple Choice

When a solution of lead (II) nitrate and a solution of sodium chloride are mixed, a cloudy white precipitate forms.

• Chemical Change

• Physical Change

Multiple Choice

At Halloween, many people use dry ice (solid carbon dioxide) in their decorations. It sublimes into a gas and creates a foggy effect.

• Chemical Change

• Physical Change

Multiple Choice

A clear, colorless crystalline solid is heated. A pale yellow-green gas is given off and a shiny, malleable metal is left behind.

• Chemical Change

• Physical Change

Multiple Choice

A shiny, dark grey metal and a clear, colorless gas combine to form a flaky orange solid.

• Chemical Change

• Physical Change

Multiple Choice

Adding sugar to tea causes the tea to taste sweeter.

• Chemical Change

• Physical Change

Multiple Choice

$$HCl\left(aq\right)+NaOH\left(aq\right)\rightarrow NaCl\left(aq\right)+H_2O\left(l\right)$$

A student has two dilute, colorless solutions, HCl(aq) and NaOH(aq), which were at the same temperature. The student combined the solutions, and the reaction represented above occurred. Which of the following results would be evidence that a chemical reaction took place?

• The resulting solution is colorless.

• The temperature of the reaction mixture increases.

• The total volume of the mixture is approximately equal to the sum of the initial volumes.

• The resulting solution conducts electricity.

Multiple Choice

A student was asked to formulate a hypothesis about what would happen if 100. mL of 0.1 M NaOH(aq) at 25^ₒC was combined with 100. mL of 0.1 M MgCl₂(aq) at 25^ₒC. Which of the following hypotheses indicates that the student thought a chemical change would occur?

• The volume of the resulting solution will be equal to the sum of the volumes of the original solutions.

• The mass of the resulting solution will be equal to the sum of the masses of the original solution.

• The resulting solution would contain a precipitate.

• The resulting solution will be clear.

Multiple Choice

A student was studying physical and chemical changes. The student carried out some procedures in the laboratory and recorded observations. For one of the procedures, the student concluded that a physical change took place, but not a chemical change. Which of the following could have been the results of the procedure?

• A cube of metal was changed into a flat sheet of metal.

• When two liquids at room temperature were combined in a beaker, the beaker became hot.

• When two clear liquids were combined, the resulting mixture was cloudy.

• When a colorless liquid was added to a blue liquid, the resulting solution was yellow.

Types of
Reactions

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion

Multiple Choice

Identify the type of chemical reaction

• Synthesis

• Decomposition

• Single replacement

• Double replacement

• Combustion