These are the types of questions you must master for the test on Ch 11 “Stoichiometery”

This sheet was given Monday 2/22/16 test will be 3/1/16 below is the review sheet and the answers follow

Also practice the full stoichiometery we have been doing in class:

Balance chemical equation (and be able to identify the 5 types: synthesis, decomposition, single replacement, double replacement and Combustion

Step 1) Convert to mole (if necessary)

Step 2) Compare moles (from the balanced chemical equations)

Step 3)Convert to quantity desired (if necessary)

For limiting reagent problems: calculate how much you need using the above steps; the chemical you run out of is the “limiting reagent”

Happy studying and good luck

Also check out the power point we used as review and the completed worksheets available on-line

There are three steps in stoichiometery (convert to moles use balanced equation convert to desired quantity) some times you only need to do the middle step or middle and one other)

Stoichiometry: box the limiting reagents in these problems (You must 1st balance the equation)

  1. ____C20 H42 + ____ O2  ____ C02 + ____H20 (combustion of wax, think of a burning candle)

a)7 mol C20 H42 reacts with 200 mol O2

b)4 mol C20 H42 reacts with 125 mol O2

  1. ____Fe2O3 + ____ CO  ____Fe + ____CO2 (reduction of iron ore, how “pig iron is often made)

a)5 mol Fe2O3 reacts with 16 mol CO

b)15 mol Fe2O3 reacts with 44 mol CO

c)0.045 mol Fe2O3 reacts with 0.145 mol CO

  1. ____H2O + ____Fe  ____Fe2O3 + ____H2 (rusting of iron, doesn’t usually happen this way but it could)

a)7.5 mol H2O reacts with 4 mol Fe

b)6.2 mol H2O reacts with 4.25 mol Fe

  1. ____H2 + ____O2  ____H2O (synthesis of water; our rocket fuel lab)

a)10 g H2 reacts with 72 g O2

b) 6 g H2 reacts with 64 g O2

Stoichiometry: box the limiting reagents in these problems (You must 1st balance the equation)

  1. 2 C20 H42 + 61 O2  40 C02 + 42 H20 (combustion of wax)

a)7 mol C20 H42 reacts with 200 mol O27 mol C20H42 would need 213.5 mol O2

b) 4 mol C20 H42 reacts with 125 mol O24 mol C20H42 would need 60 mol O2

  1. 1 Fe2O3 + 3 CO  2 Fe + 3 CO2 (reduction of iron ore)

a)5 mol Fe2O3 reacts with 16 mol CO5 mol Fe2O3 would need 15 mol CO

b)15 mol Fe2O3 reacts with 44 mol CO15 mol Fe2O3 would need 45 mol CO

c)0.045 mol Fe2O3 reacts with 0.145 mol CO0.045 mol Fe2O3 would need 0.0135 mol CO

3. 3 H2O + 2 Fe  1 Fe2O3 + 3 H2 (rusting of iron)

a)7.5 mol H2O reacts with 4 mol Fe 7.5 mol of H2O would need 5 mol Fe

b)6.2 mol H2O reacts with 4.25 mol Fe 6.2 mol of H2O would need 4.13 mol Fe

4. 2 H2 + 1 O2  2 H2O (synthesis of water)

a)10 g H2 reacts with 72 g O2 10 g H2 would need 80 g H2

b)6 g H2 reacts with 64 g O2 6 g of H2 would need 48 g O2

Start creating a review/study guide for Stoichiometery (chapter 9, 10 and 11)

What are the 7 diatomic elements?

What are the 5 types of reactions we have classified?

(when baking soda is converted to sodium carbonate what type of reaction is this (lab from2/19))

Practice balancing reactions (other side has some examples, more in the book and notes/worksheets)

What do the following symbols mean? (s) (l) (g) (aq) might also see (ppt) for precipitate

What is the difference between a liquid and a solution?

Practice naming compounds and writing the chemical formula from the name:

Barium chloride = ______barium sulfate = ______zinc (ii) sulfide = ______

Magnesium hydroxide = ______carbon tetra chloride = ______

HCl = ______H2SO4 = ______

Mole conversions you need to know and use: (dig out the old mole map or recreate, page 340 of text)

Which is more moles: 25 g NaCl or 35 g Na2SO4 ?

Show work:

How do you calculate Theoretical yield and % yield?

Given: BaCl2(aq) + Na2SO4 (aq) → 2 NaCl (aq) + BaSO4(s)

When you react 2.5 grams of barium chloride with excess (more than enough) sodium sulfate how many grams of solid Barium sulfate do you expect? (the theoretical yield)

2.5 g BaCl2= g BaSO4

If you only recover 2.65 g of barium sulfate what is your % yield?

Start creating a review/study guide for Stoichiometery (chapter 9, 10 and 11)

What are the 7 diatomic elements? I2, Br2, Cl2, F2, O2, N2, H2

What are the 5 types of reactions we have classified?

(when baking soda is converted to sodium carbonate what type of reaction is this (lab from2/19))

Baking soda decomposes to form sodium carbonate, water and carbon dioxide

5 types: synthesis, decomposition, single replacement, double replacement and Combustion

Practice balancing reactions (other side has some examples, more in the book and notes/worksheets)

What do the following symbols mean? (s) (l) (g) (aq) might also see (ppt) for precipitate

Solid, liquid, gas and aqueous solution

What is the difference between a liquid and a solution?

Liquids are pure melted substances; aqueous solution are mixtures of water and the substance that can have various concentrations

Practice naming compounds and writing the chemical formula from the name:

Barium chloride = _BaCl2__ barium sulfate = _BaSO4____ zinc (ii) sulfide = ___ZnS______

Magnesium hydroxide = ____Mg(OH)2___carbon tetra chloride = _C Cl4_____

HCl = __hydrochloric acid (a binary acid)_H2SO4 = __sulfuric acid______

Mole conversions you need to know and use: (dig out the old mole map or recreate, page 340 of text)

Which is more moles: 25 g NaCl or 35 g Na2SO4 ?

35 g NaCl = 35/58.5 = 0.60 mol NaCl 35 g Na2SO4 = 35/142.1 = 0.25 mol Na2SO4

Given: BaCl2(aq) + Na2SO4 (aq) → 2 NaCl (aq) + BaSO4(s)

When you react 2.5 grams of barium chloride with excess (more than enough) sodium sulfate how many grams of solid Barium sulfate do you expect? (the theoretical yield) 2.80g

BaCl2 = 208.3 g/molBaSO4 = 233.4 g/mol

2.5 g BaCl2= 2.80 g BaSO4

If you only recover 2.65 g of barium sulfate what is your % yield?

2.65/2.80 * 100% = 94.6%