Writing Reactions

--for unbalanced students

A few things to recall--

• Synthesis• Decomposition• Single replacement• Double replacement• Other redox

A+BAB

AB A+B

A+BC AC+BOr

D+BC C+BD

AB+CD AD+BC

AB+CD a whole bunch of other

things.

A few things to recall--

• Metallic oxides and water make hydroxides

• M2O+H2O2MOH

• MO+H2OM(OH)2

• 2M2O3+3H2O 2M(OH)3

A few things to recall--

• Nonmetallic oxides and water make acids

• YO + H2O H2YO2

• YO2 + H2OH2YO3

• YO3 + H2OH2YO4

• 2Y2O5 + H2O2HYO3

A few things to recall--

• In a single replacement reaction—the more reactive element replaces the less reactive

• X +MYY +MX means X is a more reactive nonmetal than Y• A + BCB + AC means A is a more reactive metal than B

A few things to recall--

• In a double replacement reaction, you need a molecule or a precipitate formed

• AB +CD AD + BC

if AD and BC are both soluble salts

A few things to recall--

• Carbonates decompose with heat or acid

A few things to recall--

• In a redox reaction, hydrogen ions and water can be reactants or products.

A few things to recall--

• In a redox reaction, you have to balance the charge as well

A few things to recall--

• Net ionic equations show dissociated ions, spectators are omitted

• AB +CD AD + BC, if AD is soluble,

• Write: B- +C+ BC

Predict the products

• AKA: Descriptive chemistry

• You are given to reactants. What products are formed? Go!

Predict the products

• Old Rules—– 8 sets, you choose 5– Don’t balance– Use a net ionic equation

• New rules– – Three sets, do all of them– Balance– Use a net ionic equation– Answer a question

Predict the products

• We will practice old rules first.

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride.

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride.

It will burn

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride.

Can only be

oxidized

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride.

Look for a precipitate

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride. Look for a precipitate

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride. Can be reduced

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride. Weak base

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride.

Can be reduced

What do you see?• 1. A piece of solid bismuth is heated strongly in oxygen.• 2. A strip or copper metal is added to a concentrated

solution of sulfuric acid.• 3. Solutions of zinc sulfate and sodium phosphate are

mixed.• 4. Solutions of silver nitrate and lithium bromide are mixed.• 5. A stream of chlorine gas is passed through a solution of

cold dilute sodium hydroxide.• 6. Excess hydrochloric acid solution is added to a solution of

potassium sulfite.• 7. A solution of tin (II) chloride is added to an acidified

solution of potassium permanganate• 8. A solution of ammonium thiocyanate is added to a

solution of iron (III) chloride.

It’s complex

Arrhenius acids and bases

• Substances that ionize in water to form H+ ions are acids.

• Substances that ionize in water to form OH- ions are bases.

BrØnsted-Lowry Definition

• Substances that donate a proton (H+ ion) in a reaction are acids.

• Substances that accept a proton (H+ ion) are bases.

Lewis Definition

• Substances that accept an electron pair in a reaction are acids.

• Substances that donate an electron pair are bases.

Conjugates

• After an acid has donated a proton, the rest of the species is the conjugate base.

HAA- + H+

• After a base has accepted a proton, the resulting species is the conjugate acid.

B- + H+ HB

Please recall:

• Strong acids and bases dissociate completely in a water environment. Weak acids and bases do not.

• Strong acids= nitric, hydrochloric, sulfuric, hydrobromic, hydroiodic, perchloric

• Strong bases-Group 1 & 2 hydroxides—(group 2’s might not dissolve well)

We did not use:(but you still have to know)

These ions: Precipitate like:• MnO4

-, O2-2,CN- ,ClO4

- like NO3-

• F- like Cl-• Mn+2,Fe+2 like Fe+3

• C2O4-2 like CO3

-2

• S-2 like OH-

• Hg2+2 like Ag+

• (oxides do not exist in a water solution!)

H+ + OH-H2O

• Just remember– One H+ neutralizes one OH-

• It’s true for strong and weak acids and bases.

H+ + OH-H2O

• Just remember– One H+ neutralizes one OH-

• It’s true for strong and weak acids and bases.

M1V1=M2V2

Moles of H+

Moles of OH-

A titration

• If 23.56 ml of a .115M NaOH solution neutralizes 10.00 ml of HCl solution, what is the concentration of the original acid?

Another titration

• If 14.78 ml of a .115M H2SO4 solution neutralizes 25.00 ml of NaOH solution, what is the concentration of the base?

Another titration

• If 14.78 ml of a .115M H2SO4 solution neutralizes 25.00 ml of NaOH solution, what is the concentration of the base?

Did you catch that?

Dilution

• Add more solvent to a solution, the concentration decreases.

M1V1=M2V2

Moles of

solute

Moles of

solute

A dilution

• If 150 ml of a .30 M NaOH solution is diluted to 250 ml, what is the new concentration of the base?

Another dilution

• What volume of solvent must be added to 100. ml of 1.5 M NaCl to make a solution that is .30 M [Cl-]?

Another dilution

• What volume of solvent must be added to 100. ml of 1.5 M NaCl to make a solution that is .30 M [Cl-]?

Did you catch that?

Not “to what new volume must it be diluted?”

“Life is pain, Your Highness.”

Wesley, from the Princess Bride by William Goldman

What is [Cl-]?

• 150 ml of .2 M NaCl,• 250 ml of .4 M AlCl3• 200 ml of .35 M MgCl2 and

• 100 ml H20

--are mixed (assume volumes are additive, that is, Vfinal=700 ml)

What will happen…...if you add, to 1.0 L H2O at room

temperature, the following substances, in order:

5 g Na(s)5 g Mg(s) 5 g NaCl(s)5 g Zn(C2H3O2)2(s)5 g HCl(g)5 g H3PO4(l)