Chapter 8

acid

A compound that produces hydronium (H3[subscript]O^+) ions when dissolved in water. An acid is a proton donor.

base

A compound that produces hydroxide (OH^-) ions when dissolved in water. A base is a proton acceptor.

saturated solution

A saturated solution is one that contains as much solute as the solvent can hold at a given temperature.

solute

A solute is a substance whose particles are dissolved in to the solvent, becoming a solution.

solution

A solution is a homogenous mixture of two or more substances; it is made of two parts, the solvent and one or more solutes.

unsaturated solution

A solution that has less than the maximum amount of solute that can be dissolved is called an unsaturated solution.

buffer solution

A solution that is resistant to large changes in pH. They can be made by mixing a weak acid and its salt or a weak base and its salt.

Is hydrochloric acid a base or an acid and what is its pH?

A strong acid; pH 0; HCl.

What do you add to sulfuric acid to form a salt?

A strong base such as calcium hydroxide or magnesium hydroxide.

Is sodium hydroxide a base or an acid and what is its pH?

A strong base; pH 14; NaOH.

supersaturated solution

A supersaturated solution is one that contains more solute than it can normally hold at a given temperature.

Why might the temperature of water increase when a solution is formed?

As the solute dissolves in the solvent, energy is absorbed and used to separate and break apart molecules. Once a solution is formed, this energy is released, increasing the temperature of the solution.

Why does the pH of a buffer remain relatively constant?

Because a buffer can react with both an acid and a base.

How is water either a proton donor or a proton acceptor?

Because water is neither an acid or a base, therefore it can be either a proton donor or acceptor.

Characteristics/Properties of Bases

Bitter taste, slippery feel, turns red litmus paper blue (turns purple cabbage juice blue), produces hydroxide ions when dissolved in water.

dispersion

Breaking into small pieces that spread throughout water. This is how sugar dissolves.

If you add hydrochloric acid to magnesium what will you observe?

Bubbles will form on the metal, this is hydrogen gas. HCl + Mg ------> MgCl2 + H2

What are three ways to measure the concentration of a solution?

Concentration can be expressed as percent by volume, percent by mass, and molarity.

Name the differences in the processes of ionization and dissociation?

Dissociation is a physical change, ionization is a chemical change. In dissociation, the solutes are ionic compounds. And in ionization the solutes are molecular compounds.

A solution can either become warmer or colder, why?

During the formation of a solution, energy is either released or absorbed.

What happens to energy when a solution forms?

During the formation of a solution, energy is either released or absorbed.

electrolyte

Electrolytes form ions when dissolved in water either by ionization or dissociation. They can conduct an electric current. They can either be classified as strong or weak. (Sports drinks have electrolytes.) A substance that ionizes or dissociates into ions when placed in water. (Salts)

What factors affect the rate of dissolving?

Factors that affect the rate of dissolving include surface area, stirring, and temperature, because they increase the frequency and energy of the collisions between the particles of the solute and the solvent.

How do you calculate percent by mass?

Grams of Solute/Grams of Solution X 100

Acid + Water

Hydronium + an Ion (ionization)

How might you increase the solubility of a solid in a liquid?

Increase temperature of the solute.

Why does crushing a solute increase the rate of solution?

Increased surface area affects the rate of dissolving. It reduces the particle size and increases surface area, allowing for more frequent collisions between the solute and solvent particles.

Salt + Water

Ion + Ion (dissociation)

What is the heat of solution?

It is the difference between the energy used to break attractions and the release of energy when new attractions are formed. This can either be exothermic or endothermic.

molarity

Molarity is the number of moles of a solute dissolved per liter of solution.

How do you calculate molarity?

Moles of Solute/Liters of Solution

What happens when a solution of nitric acid is added to a solution of potassium hydroxide?

Nitric acid is an acid and potassium hydroxide is a base. When they react together they neutralize and produce a salt (potassium nitrate) and water.

Why does oil not dissolve in water?

Oil does not dissolve in water because oil molecules are nonpolar and water molecules are polar. Polar molecules dissolve other polar molecules, while nonpolar molecules dissolve other nonpolar molecules; "like dissolves like."

What 3 ways can a concentration of solution be reported?

Percent by volume, percent by mass, and molarity.

What increases the solubility of a gas in water?

Pressure

How are solutions with different amounts of solute described?

Solutions are described as saturated, unsaturated, or supersaturated, depending on the amount of solute in solution.

Characteristics/Properties of an Acid

Sour, reacts with metal, blue litmus paper turns red (turns purple cabbage juice pink), produces hydronium ions when dissolved in water.

examples of strong electrolytes

Strong acids and strong bases and salts.

What are three processes that can occur when substances dissolve?

Substances can dissolve in water in three ways--by dissociation, dispersion, and ionization.

What must you know to form a saturated solution?

The amount of solute, solvent, and temperature.

How does the boiling point of a liquid solution compare to the boiling point of its solvent?

The boiling point of the solution will be higher than the boiling point of the solvent. For example, saltwater has a higher boiling point than water.

concentration

The concentration of a solution is the amount of solute dissolved in a specified amount of a solution.

solubility

The maximum amount of a solute that dissolves in a given amount of solvent at a constant temperature is called solubility.

dissociation

The process in which an ionic compound separates into ions as it dissolves is called dissociation. This process begins with an ionic compound and produces ions.

ionization

The process in which neutral molecules gain or lose electrons is known as ionization. This process begins with molecular compounds and produces ions.

neutralization

The reaction between an acid and a base. The products of this reaction are a salt and water. acid + base ----> a salt + water

How can a solute be both dilute and saturated?

The solution is saturated if it contains just enough of the solute that the solvent can hold. For a solution to be dilute means it's less concentrated. Concentration is the amount of solute dissolved in a specific amount of solution. So if you have a solute that has a hard time dissolving (not very soluble), the solution will become saturated without becoming highly concentrated.

What determines the state of the solution?

The state of the solvent.

solvent

The substance in which the solute dissolves is called the solvent.

What factors determine the solubility of a solute?

Three factors that affect the solubility of a solute are the polarity of the solvent, temperature, and pressure.

What are some properties of a solution that differ from those of its solvent and solutes?

Three physical properties of a solution that can differ from those of its solute and solvent are conductivity, freezing point, and boiling point.

How does increasing the temperature of a solvent affect the solubility of a gas?

Unlike most solids, gases usually become less soluble as the temperature of the solvent increases.

The Three Types of Solutions

Unsaturated, saturated, and supersaturated.

What would you use to safely test if an unknown substance was an acid or a base?

Use litmus paper or some other indicator like cabbage juice.

How do you calculate percent by volume?

Volume of Solute/Volume of Solution X 100

Why does water have a neutral pH?

Water contains small but equal concentrations of hydronium ions and hydroxide ions. At 25 C this concentration is 1.0 x 10^-7 M.

strong acid

When dissolved in water, strong acids ionize almost completely. HCl + H2O -----> Cl + H3O

strong base

When dissolved in water, strong bases almost completely dissociate.

Examples of Acids

acetic acid: vinegar hydrochloric acid: digestive juices in the stomach nitric acid: fertilizer sulfuric acid: car batteries

Examples of Bases

aluminum hydroxide: antacid calcium hydroxide: concrete and plaster magnesium hydroxide: laxative sodium hydroxide: drain cleaner