Acid-Base Review

Which solution is the strongest base?

• Solution D has the highest pH, meaning it has the lowest hydrogen ion concentration and is most basic.

• Solution C has a pH above 7, so it is the strongest base.

• Solution B is neutral, so it must be stronger than both acids and bases.

• Solution A has the lowest pH, meaning it has the highest hydrogen ion concentration and is the strongest base.

Answer explanation

Solution D is the strongest base because it has the highest pH, indicating the lowest hydrogen ion concentration. Higher pH values correspond to stronger basicity, making Solution D the correct choice.

Which model does the chemical equation "HCl → H⁺ + Cl⁻" best fit?

• Arrhenius Acid

• Bronsted-Lowry Acid

• Arrhenius Base

• Bronsted-Lowry Base

Answer explanation

The equation "HCl → H⁺ + Cl⁻" shows HCl dissociating into hydrogen ions (H⁺) and chloride ions (Cl⁻). This fits the Arrhenius acid model, which defines acids as substances that increase H⁺ concentration in solution.

In the equation "NH₃ + H₂O ⇌ NH₄⁺ + OH⁻", which model does NH₃ best fit?

• Arrhenius Acid

• Bronsted-Lowry Acid

• Arrhenius Base

• Bronsted-Lowry Base

Answer explanation

In the equation, NH₃ accepts a proton (H⁺) from water, forming NH₄⁺. This behavior aligns with the Bronsted-Lowry definition of a base, which is a substance that can accept protons.

Which model does the chemical equation "NaOH → Na⁺ + OH⁻" best fit?

• Arrhenius Acid

• Bronsted-Lowry Acid

• Arrhenius Base

• Bronsted-Lowry Base

Answer explanation

The equation "NaOH → Na⁺ + OH⁻" shows sodium hydroxide dissociating into sodium ions and hydroxide ions. This behavior classifies NaOH as an Arrhenius base, as it produces hydroxide ions in solution.

Which of the following is the correct name for H₂SO₄?

• Sulfurous acid

• Sulfuric acid

• Sulfate acid

• Hydrosulfuric acid

Answer explanation

H₂SO₄ is commonly known as sulfuric acid, which is a strong acid used in various industrial processes. Sulfurous acid (H₂SO₃) and hydrosulfuric acid (H₂S) are different compounds, while sulfate acid is not a standard name.

What is the formula for phosphoric acid?

• H₂PO₄

• H₃PO₃

• H₃PO₄

• HPO₄

Answer explanation

The formula for phosphoric acid is H₃PO₄, which contains three hydrogen atoms, one phosphorus atom, and four oxygen atoms. The other options represent different compounds, such as phosphorous acid or phosphate ions.

What is the typical pH range for substances that taste sour and are commonly found in citrus fruits?

• 0-3

• 4-6

• 7-9

• 10-14

Answer explanation

Substances that taste sour, like those in citrus fruits, typically have a pH range of 0-3, indicating high acidity. This is why the correct answer is 0-3, as it reflects the acidic nature of these substances.

On the pH scale, which number represents a neutral substance?

• 3

• 7

• 10

• 14

Answer explanation

On the pH scale, 7 represents a neutral substance. Values below 7 indicate acidity, while values above 7 indicate alkalinity. Therefore, the correct answer is 7.

Which point on the pH scale would best fit a substance that reacts with metals to produce hydrogen gas?

• 2

• 7

• 9

• 13

Answer explanation

A substance that reacts with metals to produce hydrogen gas is typically acidic. A pH of 2 indicates a strong acid, which can effectively react with metals, unlike neutral (7) or basic (9, 13) substances.

Which of the following is NOT a characteristic of a substance with a high concentration of hydrogen (H⁺) ions?

• Tastes sour

• Reacts with metals to produce hydrogen gas

• Feels slippery

• Commonly found in citrus fruits

Answer explanation

A high concentration of hydrogen ions (H⁺) typically results in acidic properties, which include tasting sour and reacting with metals. However, feeling slippery is characteristic of bases, not acids, making it the correct choice.