Question 1

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Accepted Answer

This is known as the dilution formula, where M1V1 = M2V2, and it holds true for dilutions with water.

Question 2

Reduction is the loss of electrons.

Accepted Answer

Reduction is the gain of electrons, not the loss of electrons.

Question 3

All acid-base reactions produce a salt and water as the only products.

Accepted Answer

Not all acid-base reactions produce a salt and water; some produce other products depending on the reactants involved. For example, reactions involving weak acids or bases can produce different products, and gas formation reactions are also common in acid-base chemistry.

Question 4

In a redox reaction, the reducing agent undergoes loss of electrons.

Accepted Answer

In a redox reaction, the reducing agent donates electrons, leading to the oxidation of the reducing agent and the reduction of the oxidizing agent. Therefore, the reducing agent undergoes loss of electrons.

Question 5

The combustion of an element is always a combination reaction.

Accepted Answer

Combustion involves an element or compound reacting with oxygen, typically resulting in the formation of one or more products, which is characteristic of a combination reaction where two or more substances combine to form a single product.

Question 6

Lithium hydroxide is used in alkaline batteries. Calculate the molarity of a solution prepared by dissolving 1.495 moles of LiOH in enough water to give a final volume of 750. mL.

Accepted Answer

Molarity = moles of solute / liters of solution

Since the volume is given in mL, we need to convert it to liters:

750. mL = 0.750 L

Now we can calculate the molarity:

Molarity = 1.495 moles / 0.750 L
Molarity = 1.99 M (rounded to two significant figures)

Therefore, the correct answer is A) 1.99 M.

Question 7

A 0.150 M sodium chloride solution is referred to as a physiological saline solution because it has the same concentration of salts as normal human blood. Calculate the mass of solute needed to prepare 275.0 mL of a physiological saline solution.

Accepted Answer

The answer of A 0.150 M sodium chloride solution is...

Question 8

In an acid-base (neutralization) reaction the equivalence point is the point where the indicator changes color.

Accepted Answer

The equivalence point in an acid-base reaction is the point at which the amount of acid equals the amount of base in moles, not necessarily the point where the indicator changes color. The indicator's color change point can vary depending on its pH range and may not exactly match the equivalence point.

Question 9

Sodium hydroxide, also known as caustic soda, is used to neutralize acids and to treat cellulose in making of cellophane. Calculate the number of moles of solute in 1.875 L of 1.356 M NaOH solution.

Accepted Answer

The number of moles of solute in a solution can be calculated using the formula: moles = molarity (M) × volume (L). For a 1.356 M NaOH solution with a volume of 1.875 L, the calculation is 1.356 M × 1.875 L = 2.543 mol.

Question 10

Some covalent compounds dissolve in water to produce conducting solutions.

Accepted Answer

Covalent compounds that ionize in water can produce conducting solutions, such as acids and some organic molecules.

Question 11

Sodium chlorate is used as an oxidizer in the manufacture of dyes, explosives, and matches. Calculate the mass of solute needed to prepare 1.575 L of 0.00250 M NaClO₃(ℳ = 106.45 g/mol).

Accepted Answer

We can use the formula:

mass = moles x molar mass

First, we need to calculate the number of moles of NaClO3:

moles = Molarity x Volume
moles = 0.00250 mol/L x 1.575 L
moles = 0.00394 mol

Then, we can calculate the mass:

mass = moles x molar mass
mass = 0.00394 mol x 106.45 g/mol
mass = 0.419 g

Therefore, the answer is choice C, 0.419 g.

Question 12

All combustion reactions are classified as combination reactions.

Accepted Answer

Combustion reactions involve the reaction of a fuel (often a hydrocarbon) with oxygen to produce carbon dioxide and water. They are not considered combination reactions because two or more reactants are not combining to form a product.

Question 13

The correct method for preparing one liter of a 1.0 M solution of X is to dissolve exactly one mole of X in exactly one liter of water.

Accepted Answer

The correct method is to dissolve one mole of X in enough water to make the total solution volume one liter, not to add it to exactly one liter of water.

Question 14

A combination reaction may also be a displacement reaction.

Accepted Answer

A combination reaction involves two or more substances combining to form a single product while a displacement reaction involves an element or ion in a compound being replaced by another element or ion. These are two different types of reactions and cannot occur simultaneously as a single reaction.

Question 15

In an acid-base (neutralization) reaction the indicator will change color at the end point.

Accepted Answer

The purpose of an indicator in an acid-base (neutralization) reaction is to show the pH of the solution. At the end point, the indicator will change color to signify that the reaction is complete and the solution has reached a neutral pH. Therefore, the statement is true.

Question 16

In a redox reaction, the oxidizing agent undergoes loss of electrons.

Accepted Answer

In a redox reaction, the oxidizing agent gains electrons and is reduced, while the reducing agent loses electrons and is oxidized.

Question 17

A particular reaction may be both a precipitation and an acid-base (neutralization) reaction.

Accepted Answer

A reaction can involve the formation of a precipitate and the neutralization of an acid and base at the same time, making it a precipitation and acid-base reaction.

Question 18

Covalent compounds, dissolved in water, never produce conducting solutions.

Accepted Answer

Covalent compounds can produce conducting solutions when they ionize or dissociate in water, such as with acids or bases.

Question 19

Oxidation is associated with an increase in oxidation number.

Accepted Answer

In oxidation, there is a loss of electrons which results in an increase in oxidation number.

Question 20

Hydrochloric acid is widely used as a laboratory reagent in refining ore for the production of tin and tantalum, and as a catalyst in organic reactions. Calculate the number of moles of HCl in 62.85 mL of 0.453 M hydrochloric acid.

Accepted Answer

We can use the formula:
moles = concentration (in mol/L) x volume (in L)
First, we need to convert 62.85 mL to L by dividing by 1000:
62.85 mL ÷ 1000 = 0.06285 L
Now we can plug in the values:
moles = 0.453 mol/L x 0.06285 L
moles = 0.0285 mol
Therefore, the answer is D) 0.0285 mol.

Quiz 4: Three Major Classes of Chemical Reactions

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Reduction is the loss of electrons.

All acid-base reactions produce a salt and water as the only products.

In a redox reaction, the reducing agent undergoes loss of electrons.

The combustion of an element is always a combination reaction.

Lithium hydroxide is used in alkaline batteries. Calculate the molarity of a solution prepared by dissolving 1.495 moles of LiOH in enough water to give a final volume of 750. mL.

A 0.150 M sodium chloride solution is referred to as a physiological saline solution because it has the same concentration of salts as normal human blood. Calculate the mass of solute needed to prepare 275.0 mL of a physiological saline solution.

In an acid-base (neutralization) reaction the equivalence point is the point where the indicator changes color.

Sodium hydroxide, also known as caustic soda, is used to neutralize acids and to treat cellulose in making of cellophane. Calculate the number of moles of solute in 1.875 L of 1.356 M NaOH solution.

Some covalent compounds dissolve in water to produce conducting solutions.

Sodium chlorate is used as an oxidizer in the manufacture of dyes, explosives, and matches. Calculate the mass of solute needed to prepare 1.575 L of 0.00250 M NaClO₃(ℳ = 106.45 g/mol) .

All combustion reactions are classified as combination reactions.

The correct method for preparing one liter of a 1.0 M solution of X is to dissolve exactly one mole of X in exactly one liter of water.

A combination reaction may also be a displacement reaction.

In an acid-base (neutralization) reaction the indicator will change color at the end point.

In a redox reaction, the oxidizing agent undergoes loss of electrons.

A particular reaction may be both a precipitation and an acid-base (neutralization) reaction.

Covalent compounds, dissolved in water, never produce conducting solutions.

Oxidation is associated with an increase in oxidation number.

Hydrochloric acid is widely used as a laboratory reagent in refining ore for the production of tin and tantalum, and as a catalyst in organic reactions. Calculate the number of moles of HCl in 62.85 mL of 0.453 M hydrochloric acid.

Quiz 4: Three Major Classes of Chemical Reactions

When a solution is diluted with water, the ratio of the initial to final volumes of solution is equal to the ratio of final to initial molarities.

Reduction is the loss of electrons.

All acid-base reactions produce a salt and water as the only products.

In a redox reaction, the reducing agent undergoes loss of electrons.

The combustion of an element is always a combination reaction.

Lithium hydroxide is used in alkaline batteries. Calculate the molarity of a solution prepared by dissolving 1.495 moles of LiOH in enough water to give a final volume of 750. mL.

A 0.150 M sodium chloride solution is referred to as a physiological saline solution because it has the same concentration of salts as normal human blood. Calculate the mass of solute needed to prepare 275.0 mL of a physiological saline solution.

In an acid-base (neutralization) reaction the equivalence point is the point where the indicator changes color.

Sodium hydroxide, also known as caustic soda, is used to neutralize acids and to treat cellulose in making of cellophane. Calculate the number of moles of solute in 1.875 L of 1.356 M NaOH solution.

Some covalent compounds dissolve in water to produce conducting solutions.

Sodium chlorate is used as an oxidizer in the manufacture of dyes, explosives, and matches. Calculate the mass of solute needed to prepare 1.575 L of 0.00250 M NaClO3 (ℳ = 106.45 g/mol) .

All combustion reactions are classified as combination reactions.

The correct method for preparing one liter of a 1.0 M solution of X is to dissolve exactly one mole of X in exactly one liter of water.

A combination reaction may also be a displacement reaction.

In an acid-base (neutralization) reaction the indicator will change color at the end point.

In a redox reaction, the oxidizing agent undergoes loss of electrons.

A particular reaction may be both a precipitation and an acid-base (neutralization) reaction.

Covalent compounds, dissolved in water, never produce conducting solutions.

Oxidation is associated with an increase in oxidation number.

Hydrochloric acid is widely used as a laboratory reagent in refining ore for the production of tin and tantalum, and as a catalyst in organic reactions. Calculate the number of moles of HCl in 62.85 mL of 0.453 M hydrochloric acid.

Sodium chlorate is used as an oxidizer in the manufacture of dyes, explosives, and matches. Calculate the mass of solute needed to prepare 1.575 L of 0.00250 M NaClO₃(ℳ = 106.45 g/mol) .