Chapter 15 section 15 2
1 / 28

Chapter 15 Section 15.2 - PowerPoint PPT Presentation

  • Uploaded on
  • Presentation posted in: General

Chapter 15 Section 15.2. Homogeneous Aqueous Systems. Think-Pair-Share. Explain why you must be extremely careful when using electricity near a swimming pool. Solutions. Aqueous Solution -Water that contains a dissolved substance. 2 Parts to a solution:

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Chapter 15 Section 15.2

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Chapter 15Section 15.2

Homogeneous Aqueous Systems


  • Explain why you must be extremely careful when using electricity near a swimming pool.


  • Aqueous Solution-Water that contains a dissolved substance.

  • 2 Parts to a solution:

    • Present in the smallest amount - Solute

    • Solvent - Present in the larger amount

  • Solvent dissolves the Solute.


  • Are Solvents and Solutes found in the liquid state only?

  • Gas Solutions

    • The air we breathe- Oxygen and Nitrogen

    • Carbon Dioxide mixed with your liquid soda

  • Solid Solutions

    • Nickel Coin- Copper and Nickel

    • Sterling Silver- Silver and Copper

  • Can you name any?


  • Homogeneous mixtures- nothing settles out when left standing

  • Solute particles are very…very small.

    • Less than 1nm = 10 -9 m

  • What would happen if we tried to filter a homogeneous solution through filter paper? Could you separate the solute from the solvent?


  • Substances that dissolve most readily in water are…

    • Ionic Compounds

    • Polar Covalent Compounds

  • Polar molecules dissolve in Polar molecules.

  • Nonpolar covalent molecules such as oils, fuels, and grease dissolve in Nonpolar covalent molecules.

The Solution Process

  • A water molecule is polar, with a partial negative charge on the oxygen atom and partial positive charges on the hydrogen atoms.

  • As individual solute ions break away from the crystal, the negatively and positively charged ions become surrounded by solvent molecules and the ionic crystal dissolves.

The Solution Process

  • The process by which the positive and negative ions of an ionic solid become surrounded by solvent molecules is called solvation.

  • This relationship can be summed up in the expression “like dissolves like.”

  • Why is the oil and water not mixing?

  • Can oil and gasoline mix?


  • An electrolyte is a compound that conducts an electric current when it is in an aqueous solution or in the molten state.

  • All ionic compounds are electrolytes because they dissociate into ions.

  • In order for the bulb to light, an electric current must flow between the two electrodes that are immersed in the solution

  • Sodium chloride, a strong electrolyte, is nearly 100% dissociated into ions in water.

  • Glucose, a nonelectrolyte, does not dissociate in water.

  • A nonelectrolyte is a compound that does not conduct an electric current in either an aqueous solution or the molten state.


  • Not all electrolytes conduct electric current to the same degree

  • In a solution that contains a strong electrolyte, all or nearly all of the solute exists as ions. Ex: Sodium Chloride

  • A weak electrolyte conducts an electric current poorly because only a fraction of the solute in the solution exists as ions.

  • Ex: Acetic Acid

  • Your cells use electrolytes, such as sodium and potassium ions, to carry electrical impulses across themselves and to other cells

  • An electrolyte imbalance can occur if you become dehydrated.

  • When you exercise, you can lose water and electrolytes from your body through perspiration.

  • Pickles contain table salt. Why can electric current flow through a pickle, causing it to glow?

  • Electrolytes conduct an electric current when they are in an aqueous solution. Table salt, or NaCl, is a strong electrolyte. The water and salt in the pickle form a solution that conducts an electric current. The electric current causes the pickle to glow.

  • Explain why you must be extremely careful when using electricity near a swimming pool.

  • The chlorinated water in a swimming pool is a solution that can conduct an electric current. If a current is introduced into the water, any swimmers could be shocked.

  • Why do appliances warn you not to use them near water?

  • Because there are electrolytes in tap water and therefore it conducts electricity.

Thumbs Up…Thumbs Down

  • All Solutions are conductors of electricity.

  • Degree of electrical conductivity is directly related to kinetic energy.

  • Ionic compounds conduct electricity because they contain ions.


  • A compound that contains water of hydration is called a hydrate.

  • The dot is not a multiplication sign.

  • It connects the compound to however many water molecules are present.


The forces holding the water molecules in hydrates are not very strong, so the water is easily lost and regained.

  • A piece of filter paper that has been dipped in an aqueous solution of cobalt(II) chloride and then dried is blue in color (anhydrous CoCl2).

  • When the paper is exposed to moist air, it turns pink because of the formation of the hydrate cobalt(II) chloride hexahydrate (CoCl2.6H2O).

Let’s test our knowledge…

  • Pg. 510 #49

  • Pg. 281 Chart 9.4

To determine what percent by mass of a hydrate is water:

  • First determine the mass of water in one mole of hydrate.

  • Then determine the molar mass of the hydrate.

  • The percent by mass of water can be calculated using the following equation:

Finding the Percent by Mass of Water in a Hydrate

  • Pg. 500 #8

  • Analyze -List the known and the unknown

  • To determine the percent by mass, divide the mass of water in one mole of the hydrate by the molar mass of the hydrate and multiply by 100%.

Let’s test our knowledge…

  • Pg. 512 #89 d and e

  • Calculate the percent by mass of water in epsom salt, magnesium sulfate heptahydrate (MgSO4.7H2O)

Test our Knowledge…

  • What property of all ionic compounds make them electrolytes?

  • Why do hydrates easily lose water when heated and regain water when exposed to moisture?

  • Identify the solvent and the solute in vinegar, a dilute aqueous solution of acetic acid.

Due Friday

  • Online assignment calculating % by mass.

  • Login