30 nov. 2010 law of conservation of mass

30 Nov. 2010Law of Conservation of Mass

Objective: SWBAT demonstrate the law of conservation of mass and show it symbolically through the use of coefficients in a balanced chemical equation.

Do now: How many atoms of each element? (This is not multiple choice!)

a) NaNO3 b) Mg(NO3)2 c) 2H2O

Agenda

I. Do nowII. Law of Conservation of Mass NotesIII. Practice ProblemsIV. DemonstrationV. Balancing Equations ExamplesVI. Practice problemsHomework: Week 13 #1-15: Weds.Lab report 1st draft: Fri.

Announcements

Did you miss the test on Wednesday?

Take it after school TODAY, or come see me to make other arrangements.

Law of Conservation of Mass

Big Picture

If 5.00 grams of oxygen are reacted with 5.00 grams of hydrogen, what mass of water is formed?

• Is there any oxygen or hydrogen left over?

• Which one? • How much?

Review of writing chemical equations

Remember: (g) = gas (l) = liquid (s) = solid (aq) = aqueous

Must use rules for naming/writing formulas Ionic compounds – balance charges,

NO prefixes Covalent compounds – use prefixes

Information from Chemical Equations

To produce fertilizers, Nitrogen gas is combined with Hydrogen gas to produce Nitrogen trihydride (ammonia).

N2(g) + H2(g) NH3(g)

Information from Chemical Equations

Making fertilizer uses a lot of energy and a lot of raw materials

Efficiency is key!! How can knowledge aboutchemical reactions make This process as efficient as possible?

1. CS2(l) + O2(g) CO2(g) + SO2(g)Liquid carbon disulfide reacts with oxygen gas to produce carbon dioxide gas and sulfur dioxide gas.

2. Solid aluminum reacts with a solution of zinc chloride to produce solid zinc and a solution of aluminum chloride.Al(s) + ZnCl2(aq) Zn(s) + AlCl3(aq)

The Law of Conservation of Mass

In a chemical reaction, matter is never created or destroyed.

The number of atoms and the mass of the reactants must be equal to the number of atoms and the mass of the products.

Demonstration

Solid sodium bicarbonate reacts with a solution of acetic acid to produce…

NaHCO3(s) + CH3COOH(aq) CO2(g) + H2O(l) + NaCO3(aq)

Initial mass:Final mass:Thoughts? Why doesn’t this reaction

satisfy (obey) the law of conservation of mass?

What could we do to make it satisfy the law of conservation of mass?

More examples:Law of Conservation of Mass

CS2(l) + O2(g) CO2(g) + SO2(g) If I reacted 5 grams of CS2 with 5 grams of O2,

and the reaction produced 2 grams of CO2, how many grams of SO2 must have been produced?

If my products had a total mass of 20 grams, how many grams of reactants must I have started with?

If I reacted 3 grams of CS2 with an unknown number of grams of O2 and produced a total of 4 grams of products, what was the mass of the O2?

A: 30 Nov. 2010

Take Out Homework: Week 13 #1-8 Objective: SWBAT use coefficients to

balance equations, satisfying the Law of Conservation of Mass

Do now: a) Write the formula equation: Hydrogen gas reacts with fluorine gas to produce hydrogen fluoride gas.b) If 3 grams of hydrogen gas is reacted with 2 grams of fluorine gas, how many grams of hydrogen fluoride gas are produced?

Agenda

I. Do now, Homework solutionsII. Balancing Equations ExamplesIII. Practice ProblemsHomework: Week 13 #9-15Lab report: Friday

How do we show, in a chemical equation, that the law of conservation of mass is being obeyed?

The law of conservation of mass must be satisfied by equalizing the number of atoms on the reactant and the product sides.

Use coefficients to show how many molecules of each compound.

Balancing Equations

H2(g) + F2(g) HF(g)

H2(g) + F2(g) HF(g)2

H2O(l) H2(g) + O2(g)

H2O(l) H2(g) + O2(g)2 2

Balancing Chemical Equations

Ca(s) + S8(s) CaS(s)

Ca(s) + S8(s) CaS(s)8 8

Zn(s) + HCl(aq) ZnCl2(aq) + H2(g)

Zn(s) + HCl(aq) ZnCl2(aq) + H2(g)2

Rules for balancing an equation

1. Only change the coefficients that appear in front of an element or compound

2. Never change any subscripts in a formula

3. Coefficients should be written as the lowest possible ratios

4. Begin by balancing elements that appear ONLY once on each side of the equation

A: 1 Dec. 2010

Take Out Homework: Week 13 #9-12

Objective: SWBAT balance chemical equations and model the law of conservation of mass.

Do now: Count the number of atoms of each element: 5Mg(NO3)2

Agenda

I. Do now, homework solutionsII. More balancing equationsIII. Paperclip bonding mini-labIV. Mole ratiosHomework: Finish Mini-Lab Handout:

Thurs.Lab Report: Fri.Read “Mass and Mole Relationships” lab

and do pre-lab (p. 2)

C: 1 Dec. 2010


Objective: SWBAT balance chemical equations and model the law of conservation of mass.

Do now: Count the number of atoms of each element: 5Mg(NO3)2

Agenda

I. Do now, homework solutionsII. More balancing equationsHomework: Week 13 Homework #16-

23Lab Report: Fri.

Examples

__CaCO3 + __HCl __CaCl2 + __CO2 + __H2O

__H2S + __O2 __SO2 + __H2O

__CaO + __HNO3 __Ca(NO3)2 + __H2O

__Fe(OH)3 __Fe2O3 + __H2O

Balancing Chemical Equations

1. __CaO + __HNO3 __Ca(NO3)2 + __H2O2. __Fe(OH)3 __Fe2O3 + __H2O3. __ZnS + __ O2 __ ZnO + __ SO2

4. __ Ag3PO4 + __KBr __K3PO4 + __ AgBr5. __ H2SO3 + __O2 __ H2SO4

6. __Na2SO4 + __Fe(NO3)3 __NaNO3 + __Fe2(SO4)3

7. __ AgNO3 + __CaCl2 __AgCl + __Ca(NO3)2

Na2O2 + H2O NaOH + O2

2Na2O2 + 2H2O 4NaOH + O2

KClO3 KCl + KClO4

4KClO3 KCl + 3KClO4

CaCl2 + Fe2(SO4)3 CaSO4 +

FeCl3

3CaCl2 + Fe2(SO4)3 3CaSO4 +

2FeCl3

Al2O3 + HCl AlCl3 + H2O

Al2O3 + 6HCl 2AlCl3 + 3H2O

AgNO3 + CaCl2 AgCl + Ca(NO3)2

2AgNO3 + CaCl2 2AgCl + Ca(NO3)2

Na2SO4 + Fe(NO3)3 NaNO3 + Fe2(SO4)3

3Na2SO4 + 2Fe(NO3)3 6NaNO3 + Fe2(SO4)3

C12H22O11 + O2 CO2 + H2O

C12H22O11 + 12O2 12CO2 + 11H2O

BaCl2 + (NH4)2CO3 BaCO3 + NH4Cl

BaCl2 + (NH4)2CO3 BaCO3 + 2NH4Cl

Liquid silicon tetrachloride reacts with liquid water to produce solid silicon dioxide and a solution of hydrochloric acid.

SiCl4(l) + 2H2O(l) SiO2(s) + 4HCl(aq)

Nitrogen gas reacts with oxygen gas and water to produce a solution of hydrogen nitrate.

2N2(g) + 5O2(g) 2H2O(l) 4HNO3(aq)

KOH + Cl2 KCl + KClO3 + H2O

6KOH + 3Cl2 5KCl + KClO3 + 3H2O

C: 3 Dec. 2010


Objective: SWBAT model the law of conservation of mass and use mole ratios to relate moles of reactants and products in a reaction.

Do now: Balance the following equation:

__ZnO(s) + __C(s) __Zn(s) + __CO2(g)

Agenda

I. Do now, homework solutionsII. Paperclip LabIII. Mole ratiosIV. Using mole ratios examplesV. Practice ProblemsHomework: Finish Paperclip mini lab

p.3-4

Chemical Bonding Paperclip Minilab

Work with your partner Designate one color paperclip as

hydrogen, one as oxygen and one as carbon. Record these choices.

Follow the directions EXACTLY, and record information in the tables.

When you finish, complete page 3.

H

HH

HH

HH

HHHH

H

O O

O O

O O

O O

O O

OO

H HH H

HH

HH

HHHH

OO

OO

OO

OO

OO

OO

CCCCCCCCCC

C

C

Mole Ratios in Chemical Equations

Why do we balance chemical equations?

Now that we can balance them, what can the coefficients tell us?

Use coefficients to form mole ratios to use as conversion factors!!

Coefficients indicate relative numbers of moles or molecules of reactants and products.

H2(g) + Cl2(g) 2HCl(g) One mole of hydrogen gas reacts

with one mole of chlorine gas to yield two moles of hydrogen chloride gas. OR:

One molecule of hydrogen gas reacts with one molecule of chlorine gas to yield two molecules of hydrogen chloride gas.

H2(g) + Cl2(g) 2HCl(g)

H HH H

Cl

ClClCl

2ZnO(s) + C(s) 2Zn(s) + CO2(g)

Zn OOZn Zn

O O

C

CZn

How many moles of zinc oxide? How many moles of carbon? How many moles of solid zinc? How many moles of carbon dioxide?

Na2O(s) + 2CO2(g) + H2O(g) 2NaHCO3(s) How many moles of sodium oxide? How many moles of carbon dioxide? How many moles of water vapor? How many moles of sodium hydrogen

carbonate?

2Al(s) + 3ZnCl2(aq) 3Zn(s) + 2AlCl3(aq)

How many molecules of aluminum? How many molecules of zinc chloride? How many molecules of zinc? How many molecules of aluminum

chloride?

Mole/Molecule Ratios

H2(g) + Cl2(g) 2HCl(g)

2H2O(l) 2H2(g) + O2(g)

How many moles of water? How many moles of oxygen gas? Mole ratio of water to hydrogen. Mole ratio of hydrogen to oxygen. Mole ratio of oxygen to hydrogen. Mole ratio of hydrogen to oxygen.

CS2(l) + 3O2(g) CO2(g) + 2SO2(g)

1. How many moles of oxygen gas?2. How many moles of carbon dioxide gas?3. Mole ratio of oxygen to carbon dioxide.4. Mole ratio of carbon disulfide to oxygen.5. Mole ratio of carbon dioxide to sulfur dioxide.6. Mole ratio of carbon disulfide to sulfur

dioxide.7. Mole ratio of carbon dioxide to oxygen.

4Fe(s) + 3O2(g) 2Fe2O3(s)

1. Molecule ratio of iron to oxygen gas.2. Molecule ratio of oxygen gas to iron

(III) oxide.3. Molecule ratio of iron (III) oxide to iron.4. Molecule ratio of oxygen gas to iron.5. How many molecules of iron?6. How many molecules of iron (III) oxide?

C: 8 Dec. 2010

Take Out Homework: Paperclip MiniLab

Objective: SWBAT calculate mole relationships for chemical reactions.

Do now: Balance the following equation:

__Fe(s) + __O2(g) __Fe2O3(s)

SWBAT calculate mole relationships for chemical reactions.

Agenda

I. Do now, homework solutionsII. Mole relationships examplesIII. Practice ProblemsHomework: Finish Week 13

Homework: TuesQuiz: Tues!

4Fe(s) + 3O2(g) 2Fe2O3(s)

Write all possible mole ratios for this equation.


Now that you can write mole ratios, we can use them to relate numbers of moles or molecules of any reactant or product to any other reactant or product.


4Fe(s) + 3O2(g) 2Fe2O3(s)1. How many moles of oxygen gas react

with 4 moles of solid iron?2. How many moles of iron (III) oxide are

produced by the reaction of 3 moles of oxygen gas?

3. How many moles of solid iron are required to react with 3 moles of oxygen gas?

4. How many molecules of iron (III) oxide are produced by the reaction of 4 molecules of solid iron?SWBAT calculate mole relationships for chemical reactions.

4Fe(s) + 3O2(g) 2Fe2O3(s)5. How many moles of O2 react with

8 moles of Fe?6. How many moles of Fe2O3 react

with 2 moles of Fe?7. How many moles of Fe react with

12 moles of O2?8. How many moles of O2 react with

16 moles of Fe?SWBAT calculate mole relationships for chemical reactions.

What if more than simple math is involved?



10 moles of Fe?2. How many moles of Fe2O3 are

produced by the reaction of 20.0 moles of O2?

3. How many moles of Fe react with 1.2 moles of O2?

4. How many moles of Fe are required to produce 7.0 moles of Fe2O3?



15 moles of Fe?6. How many moles of Fe2O3 are

produced by the reaction of 8.0 moles of O2?

7. How many moles of Fe react with 1.8 moles of O2?

8. How many moles of Fe are required to produce 13.0 moles of Fe2O3?



with 2 moles of solid iron?2. How many moles of iron (III) oxide are

produced by the reaction of 1.0 mole of oxygen gas?

3. How many moles of oxygen gas are required to produce 0.35 moles of iron (III) oxide?

4. How many moles of solid iron are required to produce 0.5 moles of iron (III) oxide?SWBAT calculate mole relationships for chemical reactions.


with 10.5 moles of solid iron?2. How many moles of iron (III) oxide are

produced by the reaction of 2.0 mole of oxygen gas?

3. How many moles of oxygen gas are required to produce 0.75 moles of iron (III) oxide?

4. How many moles of solid iron are required to produce 1.5 moles of iron (III) oxide?SWBAT calculate mole relationships for chemical reactions.

Homework

Finish Week 13 Homework Quiz Tomorrow!

Writing and balancing equations Law of Conservation of Mass Mole Ratios

We will review tomorrow before the quiz.


A: 3 Dec. 2010

Take Out Homework: Paperclip Mini Lab AND Lab

Objective: SWBAT convert between moles of reactants and products in a balanced equation.

Do now: Write all six mole ratios for the reaction, with units:

4Fe(s) + 3O2(g) 2Fe2O3(s)

Agenda

I. Do now, collect homeworkII. Moles conversions practice

problemsIII. AnswersHomework: Finish Week 13

HomeworkQuiz Tuesday

With your partner, complete the practice problems.

Check your answers on the board, and re-do problems you got wrong.

Trade the problem you wrote with a classmate. Solve that problem.

Hand in your worksheet. Work on your homework (finish

Week 13)

C: 7 Dec. 2010

Take Out Homework: Week 13 Objective: SWBAT write, balance and

calculate mole relationships for chemical reactions.

Do now: State the Law of Conservation of Mass. Explain how we show the Law of Conservation of Mass in a chemical equation.

Your quiz will be TOMORROW.

C. Agenda

I. Do now, homework solutionsII. Collect Paperclip Mini-Lab worksheetIII. Practicing Mole RelationshipsIV. Unlock the Code Review ActivityV. Pre-lab instructions and calculationsHomework: Finish Unlock the Code

worksheetQuiz Tomorrow

Moles Review

Complete this worksheet with your partner.

Ask me for help if you need it! It is due at the end of 1st period. Stay in your seat.

Unlock the Code

1. Carefully answer all four questions on the worksheet. Show all your work!

2. The code is the first digit of each answer (if a balanced chemical equation, the first coefficient! If no coefficient = 1)

3. Write the code at the top of the page, and bring it to me to try the lock.

4. When you successfully open the lock, you are finished!

Lab: Friday

Can you show the relationship between moles and mass of reactants and compounds experimentally?

How will your experimental results differ from your theoretical results?

p. 2 of lab handout

Solid sodium bicarbonate reacts with a solution of hydrochloric acid to produce carbon dioxide gas, water and a solution of sodium chloride.

The water will be evaporated to leave behind solid sodium chloride.

Formula equation?

With your partner

Balance the equation. From the balanced equation, record

the number of moles of sodium bicarbonate and the number of moles of sodium chloride.

Write a mole ratio. Write a paragraph describing the

procedure. Due Wednesday.

Homework

Finish Unlock the Code Review worksheet

Quiz Tomorrow

A: 7 Dec. 2010

Take Out Homework: Unlock the Code Worksheet

Objective: SWBAT what you know about writing and balancing chemical equations and mole relationships!

Do now: Write and balance the formula equation:

Solid aluminum reacts with oxygen gas to produce solid aluminum oxide.

Agenda

I. Do nowII. Quiz!III. Work on pre-lab: due tomorrowHomework: Completed pre-lab

When you finish the quiz, turn it over on your desk.

Remain silent. Work on the pre-lab p. 2, which is

due tomorrow. Make sure you have written an

excellent summary of the procedure!

C: 10 Dec. 2010

Take Out: Lab Worksheet (p. 2) Objective: SWBAT show empirically

the mole relationships in a chemical reaction.

Do now: a) What are the formulas of the three

products produced in this lab? b) Which product will you be finding

the mass of?

Agenda

I. Do nowII. Pre-labIII. Lab!Lab handout due at the end of the

period!No homework

SWBAT show empirically the mole relationships in a chemical reaction.

Name FormulaSolid reactant

Aqueous reactant

Solid product

Liquid product

Gaseous product

Balanced Equation Moles of sodium bicarbonateMoles of sodium chlorideratio of moles of sodium bicarbonate : moles of sodium chloride

In this lab…

Solid sodium bicarbonate reacts with a solution of hydrochloric acid to form carbon dioxide gas, water, and a solution of sodium chloride.

1. Write and balance the chemical equation.2. Predict mole ratios using the balanced

equation.3. Compare theoretical mole rations (your

prediction) with experimental mole ratios (from your experiment’s results)


Some notes on the lab

Always wear your goggles! When massing sodium bicarbonate

(baking soda) any amount between 2 and 2.5 grams is fine! Just carefully record the initial mass.

When getting 10 mL of hydrochloric acid, use the transfer pipet to do so carefully!


A hot evaporating dish looks the same as a cold one. Use tongs! Move carefully and slowly.

Never mass a hot evaporating dish. Cool your evaporating dish on the wire gauze.


When you finish working, clean up all your equipment.

Then start working on calculations and conclusions questions.

Hand in your worksheet when you finish.


During “wait time:” Answer conclusions questions Brainstorm errors and exactly how

they’ll affect your final results (the mole ratio of NaHCO3 to NaCl)

Choose one error and write it on the board, along with exactly how it affects your results and your mole ratio.

C: 8 Dec. 2010

Take Out Homework: Unlock the Code Worksheet and Moles Ratios Practice

Objective: SWBAT what you know about writing and balancing chemical equations and mole relationships!

Do now: Write and balance the formula equation:

Solid aluminum reacts with oxygen gas to produce solid aluminum oxide.

Agenda

I. Do nowII. Quiz!III. Work on pre-lab: due tomorrowHomework: Completed pre-lab

SWBAT what you know about writing and balancing chemical equations and mole relationships!

This period…

When you finish the quiz, turn it over on your desk.

Remain silent. Work on the pre-lab p. 2, which is due

tomorrow. Use information from the paragraph on

p. 1 to fill in the chart on the top of p. 2 For #2 on p. 2, write a summary of the

procedure, in your own words.SWBAT what you know about writing and balancing chemical equations and mole relationships!

Homework

Read p. 1 of the lab handout Complete p. 2

30 nov. 2010 law of conservation of mass

Documents

grams of hydrogen gas

grams of fluorine gas

grams of hydrogen fluoride

grams of oxygen

grams of products

grams of o2

grams of cs2

grams of reactants