Chemistry Solutions Overview

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Questions and Answers

Which definition best describes a base according to Arrhenius theory?

A substance that accepts protons upon ionization.

A substance that produces OH- upon ionization. (correct)

A substance that produces H+ upon ionization.

A substance that donates protons upon ionization.

What happens to Zn(OH)2 when excess NaOH is added?

It forms a solid precipitate that remains unchanged.

It dissolves to form a soluble tetrahydroxozincate complex. (correct)

It reacts to produce zinc oxide.

It produces hydrogen gas.

Which of the following substances is amphoteric?

Zn(OH)2 (correct)

KOH

CaO

NaOH

Which is the result when Cr(OH)3 reacts with H+ ions?

Cr(OH)3 is converted to Cr3+ ions. Signup and view all the answers

What is the significance of the isoelectric point in terms of ionization?

It indicates equal rates of acidic and basic ionization. Signup and view all the answers

What is defined as a homogenous mixture of two or more substances?

Solution Signup and view all the answers

In a solution, which term refers to the substance present in the largest proportion?

Solvent Signup and view all the answers

What type of solution contains a large proportion of solute relative to solvent?

Concentrated solution Signup and view all the answers

Which type of solution cannot dissolve any more of a specific solute at a particular temperature?

Saturated solution Signup and view all the answers

How much NaCl is needed to saturate a solution that currently contains 20 g of NaCl per 100 mL of water?

15.7 g Signup and view all the answers

Which of the following describes a solution that contains more solute than ordinarily required for saturation?

Supersaturated solution Signup and view all the answers

Which statement accurately describes the relationship between saturated and concentrated solutions?

Not every saturated solution is concentrated. Signup and view all the answers

What is true of an unsaturated solution?

It contains less solute than needed for saturation. Signup and view all the answers

What occurs when a tiny crystal is added to a supersaturated solution?

Crystallization of additional solute Signup and view all the answers

Which of the following is an example of a non-electrolyte?

Sugar Signup and view all the answers

What is a characteristic of weak electrolytes?

Partially dissociate in solution Signup and view all the answers

Which compound can donate a proton according to the Bronsted-Lowry theory?

Hydrochloric acid Signup and view all the answers

What type of acid can donate two protons?

Diprotic acid Signup and view all the answers

What is the result of the ionization of acetic acid in water?

Partial dissociation to hydronium and acetate ions Signup and view all the answers

What is an acidic anhydride?

An acid without water Signup and view all the answers

Which of the following describes a monoprotic acid?

Furnishes one H+ ion Signup and view all the answers

Study Notes

Solutions

A solution is a homogenous mixture of two or more substances, where the substance present in the largest amount is the solvent and the other substances are considered solutes.
Solutes dissolve in solvents.
For example, water is a solvent in a solution with salt and a solute in a solution with sugar.
An exception to the rule is concentrated sulfuric acid, in which water is the solvent, even though it makes up only 4% of the solution.
A concentrated solution contains a larger proportion of solute to solvent, while a diluted solution contains a smaller proportion.
A saturated solution is a solution where the solvent can dissolve no more solute at a particular temperature. The amount of solute that reaches saturation is defined as the solutes solubility.
An unsaturated solution contains less solute than required for saturation.
For example, at 25°C, 35.7 g of NaCl per 100 mL of water will result in a saturated solution while 20 g of NaCl per 100 mL of water will be an unsaturated solution.
If we have a 20 g/100 mL solution of NaCl, we need to add 15.7 g to make the solution saturated at 25°C.
It is important to note that saturated solutions aren't always concentrated and vice versa.
For example, a saturated solution of AgCl is 0.000089 g AgCl/100 mL, which is considered very dilute.
However, a saturated solution of Lithium Chlorate is 500 g/100 mL, which is considered concentrated.
A supersaturated solution is unstable, it contains more solute than ordinarily required for saturation. It will reach the point of saturation if:
- A crystal (seed) of solid is added, extra solute crystallizes on the seed crystal.
- The solution is further cooled.

Electrolytes and Nonelectrolytes

Nonelectrolytes are molecular substances that lack the tendency to dissociate in water. Their solutions do not conduct electricity. For example, sugar and ethyl alcohol.
Electrolytes dissociate in water, producing ions that conduct electricity.
- Strong electrolytes completely dissociate (ionize) in aqueous solutions. They conduct electricity well. For example, NaCl and HCl (strong acids and bases).
- Weak electrolytes dissociate to a small extent in aqueous solutions. They are weakly conductive to electric current. For example, acetic acid (weak acids and bases).
  - Acetic acid ionizes to only 0.42% w/v.
- Other examples of weak electrolytes are NH4OH (ammonium hydroxide) and HCN (hydrogen cyanide).
- Even water is a very weak electrolyte, only ionizing to 10-7 M.

Acids and Bases

Acids donate protons (H+) upon ionization (Arrhenius theory) and donate protons upon ionization (Bronsted-Lowry theory).
Acids can also accept a lone-pair of electrons from a base (Lewis theory).
When an acid ionizes, the conjugate base is formed.
- For example: HCl ionizes to Cl- (chloride).
Oxoacids are acids that contain Oxygen, such as HNO3, H2SO4, and H3PO4.
Monoprotic acids give away one H+ (example: HCl, HNO3).
Dioprotic acids give away two H+ (example: H2SO4).
Triprotic acids give away three H+ (example: H3PO4).
Acidic anhydrides are acids without water, such as CO2 and SO2.
Acid salts form when a base reacts with a polyprotic acid. For example, salts of H2SO4 (NaHSO4,Na2SO4) and salts of H3PO4 (Na2HPO4, NaH2PO4, Na3PO4).
Bases produce OH- upon ionization (Arrhenius Theory) and accept protons (H+) upon ionization (Bronsted-Lowry theory).
Bases can also donate a lone pair of electrons to form a coordination bond (Lewis Theory).
For example, NaOH, KOH, NH4OH (NH3).
Basic anhydrides are metal oxides, such as Na2O and CaO.

Amphoteric Substances

Amphoteric substances act as both acids and bases. Examples are some metal hydroxides.
For example, Zn(OH)2:
- Can react with NaOH, producing [Zn(OH)4]2- (tetrahydroxozincate complex).
- Can also dissolve in strong acids, producing Zn2+ and water.
Another example is Cr(OH)3:
- Can react with OH-, producing [Cr(OH)4]-
- Can react with H+, producing Cr3+ and water.
The Isoelectric point refers to the point where acidic ionization and basic ionization are equal.
Amphoteric substances have analytical applications, such as separating Al3+ from Fe3+ by adding excess NaOH, where Al3+ is precipitated as Al(OH)3, then dissolves in NaOH to form soluble sodium aluminate.
Similarly, Zn2+ can be separated from Mn2+ using the same principle.

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Description

This quiz covers the concepts of solutions in chemistry, including definitions of solutes and solvents, as well as the differences between concentrated, diluted, saturated, and unsaturated solutions. Explore key examples and the factors influencing solubility.