Thus Far…HW Questions:Reviewed: S.I, Measurement, Acc, Prec.,

Uncertainty, S.FAdded Uncertainty Propagation:

+/-: x/divide: Exponents:

Added types of error (random/systematic)Avg Deviation:

% Avg. Deviation:

Std. Deviation:

Write and balance the equation and identify the reaction type for each of the following reactions:

Chemical Reactions

Potassium metal reacts with chlorine gas

Zn metal reacts with aqueous copper(II) sulfate

Aqueous silver nitrate reacts with aqueous potassium chromate

Mercury(II) oxide reacts when heated

Butane (C4H10) reacts with oxygen

What is a(n):

Quick Review: (go..go..gadget brain)

Precipitate:

Electrolyte:

What types of combines form electrolytes?

What does strong/weak electrolyte mean?

What does soluble mean?

What does insoluble mean?

Chemical Reactions 2 major categories of inorganic chemical reactions:

Double Replacement Oxidation - Reduction

Precipitation

Neutralization

SynthesisDecompositionSingle ReplacementCombustion

Precipitation – Driving Force is formation of Precipitate (Use solubility rules to determine)Ex: AgNO3 + K2CrO4

- Molecular-Complete ionic-Net ionic

Why? Why..would you do this to us???

Equation Types:

Molecular Explicit about what the reactant solutions are and what products you obtain. Closely describes what you actually do in lab/industry.

Complete Ionic The actual “picture of what really is “in there”

Net Ionic A summary. A predictable pattern.

Write aqueous solutions as their separate ions in their actual ratios. (Ratio as coefficients: from balancing compound AND equation)

Cancel spectators ions (non-changing ions) and reduce ratio if possible.

Chemical ReactionsYou try: Write the molecular, complete ionic and net ionic equations for the reaction of aqueous aluminum sulfate with aqueous sodium hydroxide.

Neutralization – Arrhenius acid with Arrhenius base (driving force is the formation of H2O)Ex: HCl + NaOH-Molecular-Complete ionic-Net ionic

Chemical ReactionsSix Strong Acids:HClO4H2SO4HIHBrHClHNO3

Six Strong Bases:LiOHNaOHKOHCa(OH)2Sr(OH)2Ba(OH)2

Chemical ReactionsOxidation – Reduction (Redox)The following is the rxn. for the formation of rust:

Fe(s)+ O2(g) Fe2O3(s)What is the oxidation number of iron?What is the oxidation number of iron in Fe2O3?What happened?

Because it involved reacting with O2, corrosion of a metal was originally called oxidation.It was later found that similar reactions occurred without O2.Now oxidation simply means that an element has LOST electrons.

Chemical ReactionsLook back at the reaction, what happened to the O2?When an element GAINS electrons, we say that it has been reduced.The oxidation number become less/lower.A way to remember REDOX, is to think of a lion.

LEO goes GER or OIL RIGOr LEORA GEROA

In the following reaction, determine the oxidation state for each element and then determine what is reduced, oxidized; the oxidizing agent and the reducing agent: Zn + CuSO4 → ZnSO4 + CuNow do the same for butane reacting with oxygen.

Convert 3.97 x 10-14 km/ps to miles per hour. (Hint 1 mile = 1609.34 m)

(Answer = About 88 mph)

A product is milled from a single solid block of metal. Find the mass of the cube shape block measuring .600 ± .002 m per side. The block is a lead alloy with a density of .666g/mm3

If the raw block provider reports the uncertainty of their density to ± .4 %, find the mass with the calculated uncertainty

This and ThatQuiz Reminder next time we meet. (Tuesday)

Quiz will start at bell Handle your business

Do your HW Check your answers/ Questions (Before/After School) Be prepared (you know…like you used to be as chem. one students)

Return LabsGrade Checks?Mole day update (2 Weeks?)

StoichiometryLet’s look at the butane reaction once more:

2C4H10 + 13O2 → 8CO2 + 10H2O

What do the coefficients represent?

Stoichiometry is the use of these ratios to determine quantitative relationships b/w the species in a rxn.0.500 mol of butane would produce how many mol of CO2?

If 5.00g of butane reacts with an excess of oxygen how many grams of CO2 could be produced?

StoichiometryIf 5.00g of butane reacts with an 10.0g of oxygen how many grams of CO2 could be produced?

How many grams of the butane would be left when the reaction is complete?

If 7.91g of the CO2 are collected, what is the percent yield?

How many dm3?

Just for fun: When 50.0g of silicon dioxide is heated with 50.0g of carbon, 32.2g of silicon carbide is produced. The other product formed is carbon monoxide.-What is the percent yield of the reaction?-How many dm3 of carbon monoxide gas are produced?-How much excess reagent is left over?

If you don’t remember how stoich works please review the following PP from Chem 1.

More Stoich Review

Stoichiometry Practice Write the balanced equation for nitrogen

reacts with hydrogen to produce ammonia gas.A) How many grams of nitrogen would be

required to produce 14.7 g NH3?B) If 1.34 L of hydrogen reacted with an excess

of nitrogen, how many liters of ammonia would be produced?

If 18.5 g of silver nitrate reacts with an excess of sulfuric acid, how many grams of solid silver sulfate would be produced?

If 18.5 g of silver nitrate reacts with an excess of sulfuric acid, how many grams of solid silver sulfate would be produced?

Percent Yield No chemical reaction is 100% efficient.

the amount of product produced is effected by impurities, side reactions, loss of product

Theoretical yield is the maximum amount of product that can be produced. determined from stoich. problem

Actual yield is the amount of product produced.

Percent Yield = Actual Yield Theoretical Yield

X 100

Percent Yield Practice

From the last example that you worked, if only 11.8 g Ag2SO4 are actually produced, what is the percent yield?

Limiting Reagent

In almost all chemical reactions, one of the reactants will run out first and limit how much product can be produced. The reactant that runs out first is the Limiting Reagent.

Imagine you were making peanut butter and jelly sandwiches. You have 5 gallons of peanut butter, 5 gallons of jelly and 4 pieces of bread. How many sandwiches can you make? Only 2. After making 2 sandwiches you still have plenty of the

other ingredients, but you run out of bread. So the bread is the Limiting Reagent.

When you don’t know which reactant is in excess, you use each reactant to calculate the moles of product it would produce. Whichever produces the least product is the limiting reagent and you always use this lesser amount of product to calculate the theoretical yield.

Limiting Reagent Think back to the example of hydrogen

and nitrogen producing ammonia.H2(g) + N2(g) NH3(g)

If 12.1 g of nitrogen reacts with 10.4 g of hydrogen, how many grams of ammonia should be produced?

12.1 g N2 1 mol N2

28.02 g N2

x 2 mol NH3

1 mol N2

= .864 mol NH3x

10.4 g H2 x 1 mol H2

2.02 g H2

x 2 mol NH3

3 mol H2

= 3.43 mol NH3

.864 mol NH3 x 17.04 g NH3

1 mol NH3

= 14.7 g NH3

Amount of Excess Left Over

From the previous problem, how many g of the H2(g) is left over when the reaction is complete?

Subtract the theoretical yield (in moles) of the LR from the theoretical yield of the ER 3.43 mol - .864 mol = 2.57 mol

Now work backward from there to get the mass of H2: 2.57 mol NH3 x 3 mol H2 x 2.02g H2 = 7.79g H2

2 mol NH3 1 mol H2

If the problem had asked for excess L what would you do differently?

The Grand Daddy of Them All!!!What is the percent yield if 12.7 g of copper (II) nitrate react with 6.11 g of sodium hydroxide and 4.70 g of solid copper (II) hydroxideare produced?

12.7 g Cu(NO3)2 x1 mol Cu(NO3)2

187.57 g Cu(NO3)2

x 1 mol Cu(OH)2

1 mol Cu(NO3)2

=

.0677 mol Cu(OH)2

6.11 g NaOH x 1 mol NaOH40.00 g NaOH

x 1 mol Cu(OH)2

2 mol NaOH=

.0764 mol Cu(OH)2

My LR = Cu(NO3)2 and it yields .0677 mol Cu (OH)2

Continued!.0677 mol Cu(OH)2 x 97.57 g Cu(OH)2

1 mol Cu(OH)2

= 6.61 g Cu(OH)2

Percent Yield = x 100 4.706.61

= 71.1%

How much of the excess reagent is left over?

.0764 mol-.0677 mol .0087 mol Cu(OH)2

.0087 mol Cu(OH)2 x 2 mol NaOH1 mol Cu(OH)2

x 40.00 g NaOH1 mol NaOH

=

.70 g NaOH left over