Rowan Kira Talia Yikaalo

FRONT OF ROOM

Alain

Keith

Drishti

Grace

Ale

Angel

Juan

Emma

Ylana

Wilson

Michael

Sophie

Tina

Fatima

Maddie

Marpha

Alvin

Adaiha

Erik

Mario

Do-NOW Complete the graded do-now You may use your notes, handouts Do-now is SILENT and INDEPENDENT Today’s do-now is graded for

COMPLETENESS EFFORT APPROPRIATE PARTICIPATION

Objective: SWBAT convert between mass and moles of an element.

11/8/2010 Objective: SWBAT to calculate percent composition

for a compound. SWBAT determine the percentage of water in a hydrate using laboratory techniques

Agenda: do-now, percent composition, lab-finding the percentage of water in a hydrate

Homework: Complete 10 more problems (INCLUDING #20-30 if you haven’t already) in packet in preparation for QUIZ TOMORROW. Review session/extra help in chem lab, 3:15-3:40 today.

On the quiz, you will be given this:

# of Particles (atoms or molecules)

Moles Mass (in grams)

1mole6.02 x

1023particles Molar mass*

1 mole

1 moleMolar mass*

6.02 x 1023particles

1 mole* Molar mass for an element is the atomic mass from the periodic table (in grams), molar mass for a compound is the sum of the atomic masses of each atom in that compound

PERCENT COMPOSITION AND DERIVING CHEMICAL FORMULAS

Percentage the relative amount of one part compared to

the whole If I ate 2/3 of a pizza yesterday, what

percentage did I eat? Divide the part I ate by the whole (2 / 3) to

get a decimal = .67 Multiply the decimal by 100 = 67 I ate 67% of the pizza

Percentage If 6 of my 30 fish are blue, what

percentage of my fish are blue? 6 / 30 = .2 .2 x 100 = 20%

If I got a 15/45 on my Chemistry test, what percentage did I get right? 15/45 = .33 .33 x 100 = 33%

Questions about calculating a percentage?

Percent Composition the amount of a compound that is made up

of a certain element – measured by MASS Ex: What percentage of Carbon Monoxide is

made up of Carbon? First need to find mass of whole compound

12g + 16g = 28g Now divide mass of the part (carbon) by the

mass of the whole (carbon monoxide) 12g/28g = .43 .43 x 100 = 43% Carbon Monoxide is 43% carbon

Percent Composition Ex 2 – what percentage of water is made

up of hydrogen? Total mass: (2 x 1g) + 16g = 18g Part / whole: 2g/18g = .11 .11 x 100 = 11% Water is 11% Hydrogen

Percent Composition Ex 3 – what percentage of water is made

up of oxygen? Find total mass: (2 x 1g) + 16g = 18g Part/whole : 16g/18g = .89 .89 x 100 = 89% Water is 89% oxygen

Percent Composition Ex 3: What is the percent composition of

each element in dinitrogen trioxide? HINT – make sure they sum to 100%

Lab – water of hydration Hydrate – An ionic compound that contains

water molecules as part of its crystal structure

Naming/writing formulas CaCl2 •2H2O – Calcium Chloride dihydrate This is a compound where each molecule of

calcium chloride is combined with 2 molecules of water in the crystal structure

The prefixes are the same as for naming compounds

Lab – water of hydration Anyhdrous – The form of a hydrate-

forming compound with NO water in its structure

Salt – An ionic compound

Lab – water of hydration Objective: To determine the percentage

of water in a hydrate, and to calculate the ratio of the number of moles of water to the number of moles of anhydrous salt molecules.

You will be removing the water from a hydrate and calculating how much water was in it and then using that value to calculate the formula for the compound

CuSO4·XH2O(s) CuSO4(s) + H2O(g)

Lab – water of hydration Follow instructions carefully – you will be graded

on the completion and correctness of your data Goggles must be worn at all times Procedure… Be careful with hot plates and hot beakers – do

not put hot beakers on the balance Remember to mass your beaker and then to

subtract it from all mass readings Heat your compound until it is entirely

white/light blue – and then a little more (don’t burn it)

Rowan Kira Talia Yikaalo

FRONT OF ROOM

Alain

Emma

Drishti

Grace

Sophie

Juan

Angel

Keith

Ylana

Wilson

Michael

Ale

Tina

Fatima

Maddie

Marpha

Alvin

ErikMario Adaiha

The person who’s name is in BOLD is the only person who may leave his/her seat during this lab

Do-NOW Put away everything except:

A pencil A calculator Your homework (to hand in)

Objective: SWBAT convert between mass and moles of an element.

11/8/2010 Objective: SWBAT to demonstrate facility

with various stoichiometric calculations

Agenda: quiz, work on lab packet from yesterday

Homework: Week 11 HW, #1-5, LAB PACKET DUE FRIDAY – see me if you need help!

QUIZ DO NOT WRITE ON PERIODIC TABLE Stoichiometry road map is yours to keep

– use it to study for test. You will not be given this on the test.

What does it mean to show all work? Write given, with unit, over one Write a fractional conversion factor next to

it Show that units cancel ALL VALUES MUST HAVE UNITS

Do-NOW Complete the graded do-now You may use your notes, handouts Do-now is SILENT and INDEPENDENT

Objective: SWBAT convert between mass and moles of an element.

11/7/2010 Objective: SWBAT to differentiate

between empirical and molecular formula. SWBAT find the molecular formula given the empirical formula and the molar mass.

Agenda: do-now, notes, practice problems

Homework: Week 11 HW, #6-8, LAB PACKET DUE FRIDAY – see me if you need help!

Molecular Formula Gives a complete list of all

the atoms in a molecule

EX: H2O 2 atoms of H, 1 of O

EX: C6H12O6 6 atoms of c, 12 of H, 6 of

O

Empirical Formula Just gives the lowest, whole number RATIO

of elements in the compound

EX: Glucose (Molecular formula: C6H12O6) Empirical Formula: CH2O

EX: Water (Molecular formula: H2O) Empirical Formula: H2O

What is the empirical formula for each of the following?

H2O2

CH4

C2H10

C12H22O11

Finding Molecular formula What is the molecular formula for a compound with

the empirical formula HO and a molar mass of 34g? STEP 1 – find the total mass of the empirical

formula given to you 1g + 16g = 17g

STEP 2 – divide the molar mass from the problem by the mass of the empirical formula 34g / 17g = 2

STEP 3 – multiply each subscript in the emp. form by the number you just found H2O2

Ex 2 What is the molecular formula for a compound

with the empirical formula CH3 and a molar mass of 45g?

STEP 1 – find the total mass of the empirical formula given to you 12g + (1g x 3) = 15g

STEP 2 – divide the molar mass from the problem by the mass of the empirical formula 45g / 15g = 3

STEP 3 – multiply each subscript in the emp. form by the number you just found C3H9

Ex 3 What is the molecular formula for a

compound with the empirical formula NO2 and a molar mass of 138g?

14g + (16g x 3) = 46g 138g / 46g = 3 N3O6

Homework: Week 11 HW, #6-8LAB PACKET DUE FRIDAY – see me if you

need help!

Do-NOW Complete the graded do-now You may use your notes, handouts Do-now is SILENT and INDEPENDENT

Objective: SWBAT convert between mass and moles of an element.

11/18/2010 Objective: SWBAT to write the empirical

formula for a compound given laboratory data

Agenda: do-now, notes, practice problemsLAST NEW MATERIAL BEFORE THANKSGIVING!!

Homework: LAB PACKET– see me if you need help! Make sure WK 11 #1-8 is finished and ready to go over tomorrow.

Extra Help – Today (Thursday) 3:15-4:15

Finding Empirical Formula in the Lab

When we do Analytical Chemistry in the lab, we can find values for the amount of a certain element in a compound

Like when we found the amount of water in CuSO4 • XH2O

We have a system for taking the values we get in the lab and figuring out the empirical formula

Determine the empirical formula for a compound that is 74.83% carbon and 50.34% hydrogen by mass

STEP 1 - Pretend you have 100 grams of the substance, make the % values into numbers of grams

74.83g of carbon 50.34g of hydrogen

STEP 2 - Convert each mass value into moles74.83g carbon x 1 mole . = 6.24 moles

carbon1 12 g carbon

50.34g hydrogen x 1 mole . = 50.34 moles H1 1 g hydrogen

Determine the empirical formula for a compound that is 74.83% carbon and 50.34% hydrogen by massSTEP 3 - Divide all mole values by smallest

# of moles50.34 moles / 6.24 moles = 8.076.24 moles / 6.24 moles = 1STEP 4 - Use the resulting numbers as your

subscripts CH8

Determine the empirical formula for a compound that is 37.41% carbon and 25.17% hydrogen by massSTEP 1 - Pretend you have 100 grams of

the substance, make the % values into numbers of grams

STEP 2 - Convert each mass value into moles

STEP 3 - Divide all mole values by smallest # of moles

STEP 4 - Use the resulting numbers as your subscripts

Ascorbic acid is another name for Vitamin C. It is composed of 40.92% carbon, 4.58% hydrogen, and 54.50% oxygen, by mass. Determine the empirical formula for ascorbic acid.

STEP 1 - Pretend you have 100 grams of the substance, make the % values into numbers of grams

STEP 2 - Convert each mass value into molesSTEP 3 - Divide all mole values by smallest # of

molesSTEP 4 - Use the resulting numbers as your

subscripts

Finding Empirical Formula Sometimes you won’t be given percentages,

but values for each element out of a total value Ex: what is the empirical formula for a

compound where a 5g sample contains 1.2g Carbon and 3.8g of Nitrogen.

To solve: find the percentage of each element, then proceed as before

1.2g Carbon / 5 g = .24 x 100 = 24% Carbon 3.8g Nitrogen / 5g = .76 x 100 = 76% Nitrogen

A 4.99 gram sample of a compound contains 1.52 grams of nitrogen atoms and 3.47 grams of oxygen atoms.

A 16.67g sample contains11.66 g iron and 5.01 g oxygen. What is its empirical formula?

Homework LAB PACKET Make sure to have WK 11 #1-8 finished

and ready to go over tomorrow. See me if you need help!

Do-NOW Complete the graded do-now You may use your notes, handouts Do-now is SILENT and INDEPENDENT

Objective: SWBAT convert between mass and moles of an element.

11/18/2010 Objective: SWBAT

Agenda: do-now,

Homework: Week 11 HW # 9-16 (17 as a bonus), Start preparing for test next WEDNESDAY