Ions-needed for life!Dr. Robert D. Craig, Ph.D.

• Experiment on rections of ions with acids and bases

• Ions effect pH• Ions effect Diffusion• Ions effect Homeostasis• Ions are responsible for nervous system

Let’s begin

Ions-needed for life

• Ions effect pH• Ions effect Diffusion• Ions effect Homeostasis• Ions are responsible for nervous system

Nine essential

• PO4 2- Mg 2+

• OH- Ca 2+

• HCO32- Na+

• Cl- K+ , H+

• Nervous system• pH• Ion channel-lipid bilayer• Fe2+-Hemoglobin

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• • In Part A, a series of tests for the chemical

properties of known compounds in aqueous solutions are conducted. A similar series of tests are conducted on an unknown set of compounds in Part B.

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• A similar series of tests are conducted on a unknown set of compounds in Part B. In each case, an unknown compound is identified

For the reaction matrix

• You should discuss and interpret your observations as follows:

Please label everything

• You will carry out 15 chemical reactions against these reagents

• Sodium Chloride• Sodium Carbonate• Magnesium Sulfate• Ammonium Chloride• Water

Your matrix for reagent one (1)NaCl(s) Na2CO3(aq) MgSO4(aq) NH4Cl(aq) H2O(l)

AgNO3(aq)

terminology

• The report sheet or the “Reaction matix”• Is designed to help organized Your work• Because the space is limited –You can use codes to

fill in data:• “P” – precipitate + color• “c” – cloudy + color• “nr”- no reaction• “g” –gas no odor• “go” –gas , odor

What is the nature of a chemical reaction>

Most reactions take place

Scientist describe reactions in terms of:

• Molecular• Total Molecular• Net Ionic: “it is the net ionic that contains the

important players” The rest of the reaction are “spectators”

How do I know a chemical reaction has taken place????

What to look for . . .

• A gas evolved• A precipitate “solid” appears• Heat may be evolved or absorbed• A color change might take place• A change in odor• Possibly a “sound”

H2S – rotten eggs

• For well over a century, hydrogen sulfide was important in analytical chemistry, in the qualitative inorganic analysis of metal ions. In these analyses, heavy metal (and nonmetal) ions (e.g., Pb(II), Cu(II), Hg(II), As(III)) are precipitated from solution upon exposure to H2S. The components of the resulting precipitate redissolve with some selectivity

silver chloride (AgCl)

• An example of a precipitation reaction: Aqueous silver nitrate (AgNO3) is added to a solution containing potassium chloride (KCl), the precipitation of a white solid, silver chloride is observed. (Zumdahl, 2005)

• AgNO3 (aq) + KCl (aq) → AgCl (s) + KNO3 (aq)• The silver chloride (AgCl) has formed a solid,

which is observed as a precipitate.

the ionic equation

• This reaction can be written emphasizing the dissociated ions in a combined solution. This is known as the ionic equation.

Ag+ (aq) + NO3− (aq) + K+ (aq) + Cl− (aq) →

AgCl (s) + K+ (aq) + NO3− (aq)

(Zumdahl, 2005)

• A final way to represent a precipitate reaction is known as a net ionic reaction. In this case, any spectator ions (those that do not contribute to the reaction) are left out of the formula completely. This simplifies the above equations to the following:

• Ag+ (aq) + Cl− (aq) → AgCl (s)•

Oxidation and reduction

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• In addition, the following multistep acid-base reactions affect the course of rust formation:

• Fe2+ + 2 H2O   Fe(OH)⇌ 2 + 2 H+

• Fe3+ + 3 H2O Fe(OH)⇌ 3 + 3 H+

Simple dissolution MgOH2

Burning Mg(s)Mg(s) + O2 (g) -> MgO(s) + Heat + light

Heat may be absorbed

• Icy –hot or sprinkling salt on snow

Please Turn to figures . . .

• 2.2a and 2.2b

2. Observations sodium hydroxide test reagent

• 1. label five tubes(fig 2.3)• 2. set up 24 well plate• ***Label B1-B5• 3. Place 5-10 drops of each of the five known• Solutions• 4. Deliver the NaOH—check for Gas!!!• 5. Please be careful!!!!!!

3. Observations with HCl reagent

• 1. label five tubes(fig 2.4)• 2. set up 24 well plate• ***Label C1-C5• 3. Place 5-10 drops of each of the five known• Solutions• 4. Deliver the HCl—check for Gas!!!• 5. Please be careful!!!!!!

Part B

• Chemical properties of unknown solutions• 1. preparation of solutions• 2. preparation of reagents• 3. testing the solutions• 4. Identification of unkwown

Last part –environmental testing

• Obtain a sample of soil , add water

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