Identify Acids and Bases

A group of students conducts an experiment to identify which of their unknown liquids are acids and which are bases. They use a pH indicator and collect the following data: Liquid | pH --- | --- Liquid 1 | 6 Liquid 2 | 3 Liquid 3 | 12 Pure water | 7 Which statement identifies the acids and bases in the data table?

• Liquid 3 has a pH higher than pure water, so it is an acid. Pure water has a neutral pH, so it is a base.

• Liquid 2 has a pH lower than pure water, so it is a base. Pure water has a neutral pH, so it is an acid.

• Liquid 3 has a pH higher than pure water, so it is a base. Liquid 2 has a pH lower than pure water, so it is an acid.

• Pure water has a neutral pH, so it is a base. Liquid 1 has a pH lower than pure water, so it is an acid.

What test can the students perform to correctly and safely identify acids and bases?

• Litmus test

• Boiling point test

• Melting point test

• Density test

Which is an acid?

• Turns blue litmus red

• Turns red litmus blue

• Has a pH of 11

• Has a pH of 7

Tags

NGSS.MS-PS1-2

Kiva notices that the ingredients label on her drink includes citric acid. She wonders how the acid affects her drink. Which statement describes a possible effect citric acid could have on the drink?

• It could add a sour flavor to the drink.

• It could add a bitter flavor to the drink.

• It could make the drink more neutral.

• It could make the drink turn red litmus paper blue.

Sofia is doing a lab to determine the pH of a solution in a beaker. During the lab, she finds that the pH of her solution is too high. She needs to lower the pH to be closer to 5. She has 3 different droppers that contain pure water, a concentrated acid, and a concentrated base, as shown. How can she use the droppers to lower the pH?

• Add drops of the concentrated base to the beaker.

• Add drops of the concentrated acid to the beaker.

• Add drops of pure water to the beaker.

• Add a few drops from each dropper to the beaker.

Azami’s mom loves drinking tomato juice but often complains about an upset stomach. Azami thinks it is because the tomato juice is too acidic. He suggests she add something to her tomato juice to help make it more neutral. The data table shows the pH of tomato juice, milk, and lemon juice. Substance | pH --- | --- Tomato juice | 4 Milk | 7 Lemon juice | 3 Which option would help produce a less acidic, more neutral drink?

• Milk

• Lemon juice

Tags

NGSS.MS-PS1-2

The pH scale is used to measure how acidic or basic something is. A pH value lower than 7 indicates a substance is ________, while a pH value higher than 7 is considered ________. Pure water is considered ________, with a pH of ________.

• A. acidic; acidic; neutral; 12

• B. acidic; basic; neutral; 7

• C. basic; acidic; basic; 1

• D. neutral; basic; basic; 7

Which of the following is an acid?

• vinegar

• bleach

• sugar in water

• starch in water

• toothpaste in water

Choose the correct answer. Acid or base?

• Acid

• Base

Tags

NGSS.MS-PS1-2

Which of the following formulas below are acids? ( Select ALL that apply)

• H₂SO₄

• HCl

• NaOH

• CaCO₃