Solutions The homogeneous mixture of a solute dissolved

  • Slides: 49
Download presentation
Solutions

Solutions

The homogeneous mixture of a solute dissolved in a solvent is called a “solution”.

The homogeneous mixture of a solute dissolved in a solvent is called a “solution”.

The “solute” is the substance being dissolved. ex. Na. Cl in Na. Cl(aq)

The “solute” is the substance being dissolved. ex. Na. Cl in Na. Cl(aq)

The solute is often a solid, but it doesn’t have to be. Solutes can

The solute is often a solid, but it doesn’t have to be. Solutes can be gases or even liquids. ex. NH 3 in NH 3(aq)

The “solvent” is the liquid that is dissolving the solute. ex. water in Na.

The “solvent” is the liquid that is dissolving the solute. ex. water in Na. Cl(aq)

“Concentration” expresses how “strong” or “weak” a solution is.

“Concentration” expresses how “strong” or “weak” a solution is.

If a “small” amount of solute is dissolved in a “large” amount of solvent,

If a “small” amount of solute is dissolved in a “large” amount of solvent, the solution is considered weak or “dilute”.

If a “large” amount of solute is dissolved in a “small” amount of solvent,

If a “large” amount of solute is dissolved in a “small” amount of solvent, the solution is considered strong or “concentrated”.

A “saturated solution” contains the maximum amount of solute that can dissolve in the

A “saturated solution” contains the maximum amount of solute that can dissolve in the solvent.

Another way of saying this is a solution is saturated when the maximum concentration

Another way of saying this is a solution is saturated when the maximum concentration is reached.

If more of a substance is added to a saturated solution, it can NOT

If more of a substance is added to a saturated solution, it can NOT dissolve.

“Precipitate” is the solid substance that settles to the bottom of a saturated solution

“Precipitate” is the solid substance that settles to the bottom of a saturated solution and does NOT dissolve.

There are 3 factors that determine how well a solute will dissolve in a

There are 3 factors that determine how well a solute will dissolve in a solvent.

Factor #1 What is the solute and how much of it are you trying

Factor #1 What is the solute and how much of it are you trying to dissolve?

Factor #2 What is the solvent and how much of it are you dissolving

Factor #2 What is the solvent and how much of it are you dissolving the solute in?

Factor #3 What is the temperature of the solute?

Factor #3 What is the temperature of the solute?

In general, solid solutes dissolve better when the temperature of the liquid solvent is

In general, solid solutes dissolve better when the temperature of the liquid solvent is higher.

In general, gaseous solutes dissolve better when the temperature of the liquid solvent is

In general, gaseous solutes dissolve better when the temperature of the liquid solvent is lower.

When answering questions about solubility and temperature, always refer to Table G!

When answering questions about solubility and temperature, always refer to Table G!

Another important factor affecting solubility is the polarity of the solute and the polarity

Another important factor affecting solubility is the polarity of the solute and the polarity of the solvent.

In general, ionic substances dissolve better in polar liquids like water because of the

In general, ionic substances dissolve better in polar liquids like water because of the molecule-ion attractions that occur.

In general, polar molecules dissolve better in polar liquids such as water.

In general, polar molecules dissolve better in polar liquids such as water.

In general, non-polar molecules dissolve better in non-polar liquids such as oil.

In general, non-polar molecules dissolve better in non-polar liquids such as oil.

“Likes Dissolve Likes!”

“Likes Dissolve Likes!”

Predict the solubility in water or oil: NH 3 I 2 gasoline KMn. O

Predict the solubility in water or oil: NH 3 I 2 gasoline KMn. O 4 CH 4 HCl KBr sugar CO 2

In most double replacement reactions in solution, one of the products formed will be

In most double replacement reactions in solution, one of the products formed will be a precipitate.

Remember to use Table F to determine if a precipitate will form!

Remember to use Table F to determine if a precipitate will form!

In general: Solids dissolve better at a higher temperature. Gases dissolve better at a

In general: Solids dissolve better at a higher temperature. Gases dissolve better at a lower temperature.

Pressure only has a significant effect on the solubility of gases. Solids and liquids

Pressure only has a significant effect on the solubility of gases. Solids and liquids are Not affected by pressure changes.

Gases dissolve better at high pressure. Gases don’t dissolve as well at low pressure.

Gases dissolve better at high pressure. Gases don’t dissolve as well at low pressure.

Properties of Solutions

Properties of Solutions

Chemists often use “Molarity” to express the concentration of a solution “quantitatively” (with numbers).

Chemists often use “Molarity” to express the concentration of a solution “quantitatively” (with numbers).

Molarity (M) = moles of solute liters of solution (Molarity is measured in moles/liter

Molarity (M) = moles of solute liters of solution (Molarity is measured in moles/liter and can be found on Table T) Also helpful Moles = grams GFM (g/mole)

‘ppm’ (parts per million) is a term that is also used to express a

‘ppm’ (parts per million) is a term that is also used to express a concentration

The equation: ppm= grams of solute grams of solution This can also be found

The equation: ppm= grams of solute grams of solution This can also be found on Table T

% mass of a compound in solution is sometimes referred to as pph -

% mass of a compound in solution is sometimes referred to as pph - parts per hundred

Any dissolved substance will lower the freezing point and raise the boiling point of

Any dissolved substance will lower the freezing point and raise the boiling point of a solvent.

The greater the concentration of dissolved particles is, the greater the effect will be.

The greater the concentration of dissolved particles is, the greater the effect will be.

freezing point boiling point O o. C more dissolved particles 100 o. C pure

freezing point boiling point O o. C more dissolved particles 100 o. C pure water more dissolved particles

Each mole of dissolved particles in 1000 g of water will lower the o

Each mole of dissolved particles in 1000 g of water will lower the o freezing point by 1. 86 C.

Each mole of dissolved particles in 1000 g of water will raise the boiling

Each mole of dissolved particles in 1000 g of water will raise the boiling point by 0. 52 o. C.

“Electrolytes” are substances that ionize (form charged particles) and conduct electricity when they are

“Electrolytes” are substances that ionize (form charged particles) and conduct electricity when they are dissolved in water.

In general, ionic solutes (electrolytes) effect freezing and boiling points greater than covalent solutes

In general, ionic solutes (electrolytes) effect freezing and boiling points greater than covalent solutes (nonelectrolytes) do. Why?

Nonelectrolytes NH 3(aq) (1 mole produces 1 mole) C 6 H 12 O 6(aq)

Nonelectrolytes NH 3(aq) (1 mole produces 1 mole) C 6 H 12 O 6(aq) (1 mole produces 1 mole)

Electrolytes Na. Cl Na+(aq) + Cl-(aq) (1 mole produces 2 moles!) Ca. Cl 2

Electrolytes Na. Cl Na+(aq) + Cl-(aq) (1 mole produces 2 moles!) Ca. Cl 2 Ca+2(aq) + 2 Cl-(aq) (1 mole produces 3 moles!)

Vapor pressure - pressure exerted by molecules of a liquid as it evaporates

Vapor pressure - pressure exerted by molecules of a liquid as it evaporates

Boiling occurs when: vapor pressure = atmospheric (air) pressure

Boiling occurs when: vapor pressure = atmospheric (air) pressure

Always refer to Table H when answering questions about vapor pressure and boiling point!

Always refer to Table H when answering questions about vapor pressure and boiling point!