Acids and Bases

Students were asked to test several unknown substances to determine if the substances are acids or bases. During the first test, a drop of phenolphthalein turned the unknown solution bright pink. What can be inferred about the substance?

• It is neutral.

• It tastes sour.

• It has a pH ranging from 1-6.

• It has a pH ranging from 8-14.

A student is given three unknown solutions and asked to identify each solution as being acidic, basic, or neutral. The student uses a pH probe to test each solution and records the data in a table.

Which argument is supported by the data?

• All solutions are acidic because they fall within the pH range of 2 to 9.

• All solutions are basic because they fall within the pH range of 2 to 9.

• Solutions 1 and 3 are acidic because they have a pH above 7, and Solution 2 is basic because it has a pH below 7.

• Solutions 1 and 3 are basic because they have a pH above 7, and Solution 2 is acidic because it has a pH below 7.

Tags

NGSS.MS-PS1-2

Three students are experimenting with substance X. Their observations are listed in the table.

Which number could best represent the pH of substance X?

• 3.6

• 7.0

• 8.3

• 14.0

Tags

NGSS.MS-PS1-2

The table shows pH data on five different substances.

Which letter represents the most acidic substance?

• V

• W

• Y

• Z

The pH of a substance identifies a substance as an acid or base.

Which substance is a base?

• S

• T

• U

• V

A student measures the pH of different body fluid samples and records the data in a table, as shown.

Which statement correctly describes the relative pH of two of the samples?

• Pancreatic juice and urine are acids with high pH values.

• Gastric juice and blood plasma are bases with low pH values.

• Gastric juice and urine are acids with low pH values.

• Pancreatic juice and urine are bases with high pH values.

A student has two solutions (J and K) made of edible household products. The student studies the physical properties of the two solutions and records observations in a table, as shown.

How can Solutions J and K be classified?

• Solution J: basic; Solution K: acidic

• Solution J: acidic; Solution K: basic

• Solution J: basic; Solution K: neutral

• Solution J: acidic; Solution K: neutral

A teacher gives three unknown solutions (X, Y, and Z) to her students. The students test the solutions using red and blue litmus and phenolphthalein, and they record their observations in a table, as shown.

Which solution(s) can be classified as an acid?

• X only

• Y only

• X and Z

• Y and Z

Tags

NGSS.MS-PS1-2

As digested food leaves the esophagus and enters the stomach, the pH changes from 7.0 to 2.5. The partially digested food changes from a pH of 2.5 to 7.4 as it leaves the stomach and enters the small intestine.

How does the food pH change as it travels from the esophagus to the small intestine?

• The pH changes from basic to neutral to slightly acidic.

• The pH changes from neutral to acidic to slightly basic.

• The pH changes from acidic to basic to neutral.

• The pH changes from neutral to basic to acidic.

Which statement accurately describes water?

• It is a basic solution.

• It is a neutral solution.

• It will turn bright pink when phenolphthalein is added.

• It will turn red litmus paper a blue color upon contact