Pure Substances and Mixtures

Madison's lab group is given a dish that contains sand, shells, and water. How should they classify the substance they have been given?

• compound because it contains several elements

• pure substance because it’s made up of various compounds

• heterogeneous mixture because it does not have the same uniform appearance or composition

• homogeneous mixture because it has the same uniform appearance and composition throughout

Examine the models on the left.

Which model represents a pure substance?

• Model 1,

  because it represents compounds.

• Model 2, because it represents several elements.

• Model 3, because it represents one type of compound.

• Model 4, because it contains both elements and compounds.

Tags

NGSS.MS-PS1-1

The graph shows the composition of the air we breathe.

Which of the following statements correctly classifies the air we breathe?

• The air we breathe is an element.

• The air we breathe is a compound.

• The air we breathe is a homogeneous mixture.

• The air we breathe is a heterogeneous mixture.

Tags

NGSS.MS-PS1-1

4. Soda water is formed by mixing carbon dioxide (CO2) with distilled water (H2O). Classify the two substances based on the information provided.

• Soda water and distilled water are both heterogeneous mixtures.

• Soda water is a homogeneous mixture and distilled water is a pure substance.

• Soda water is a pure substance while distilled water is a homogeneous mixture.

• Soda water and distilled water contain hydrogen and oxygen, therefore they are both pure substances.

Use the image of the pH scale to answer the following question.

What would the outcome of a solution be, if Gastric Juice and Sodium Hydroxide (as shown in the pH scale above) are mixed in a beaker during a lab?

• a salt solution

• a more basic solution

• a neutral acid solution

• a more acidic solution

Tags

NGSS.MS-PS1-2

The table below shows various solutions and their pH.

Which of the above substances is considered an acid?

• Lye

• Soda

• Borax

• Water

The image to the left contains a list of common household cleaners and their pH levels.

The more basic a solution is the better it performs as a cleaning agent. Which of the following would make the best cleaning agent and why?

• Vinegar would be the best cleaner, because it has a pH of 3.

• Toilet Bowl Cleaner would be the best cleaner, because its pH is 1-3.

• Mild Dish Soap would be the best cleaner because it has a pH is closest to neutral.

• Tub & Tile Cleaner would be the best cleaner, because it has a pH of approximately

  11-13.

Tags

NGSS.MS-PS1-2

Use the image below to answer the following question.

Based on the pH scale, which substance is more acidic than tomato juice?

• Lemon juice has a lower pH therefore it is more acidic than tomato juice.

• Baking soda has a lower pH therefore it is more acidic than tomato juice.

• Black coffee has a greater pH therefore it is more acidic than tomato juice.

• Milk has a pH closest to neutral therefore it is more acidic than tomato juice.

Tags

NGSS.MS-PS1-2

Which of the following describes rice and beans combined in a bowl?

• compound

• pure substance

• homogenous mixture

• heterogeneous mixture

Which of the following is formed when salt is dissolved in water?

• solution

• compound

• pure substance

• heterogeneous mixture