Topic 4.4: Physical and Chemical Changes

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

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

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

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

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

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

Adding sugar to tea causes the tea to taste sweeter.

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

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?

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?

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?

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction

Identify the type of chemical reaction