ThursdayJanuary 31, 2013

(Mass to Mole Stoichiometry)

mol HgO

5.0 mol HgO

HgO æ Hg + O2

Bell RingerThursday, 1-31-13

If 5.0 moles of mercury (II) oxide decompose, how many grams of mercury will be produced?

2 25.0 mol ? grams

X1

=mol Hg

2 g Hg2 1005X

g Hg

mol Hg1201

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Assignment Currently Open

Summative or

Formative?Date

Issued Date Due Date Into GradeSpeed Final Day

QUIZ 16 S1 1/18 1/18 1/24 2/7

WS - Introduction to Stoichiometry and Mole Ratios

F7 1/23 2/1 TOMORROW

WS – Review of Molar Mass F8 1/24 2/1 TOMORROW

Project Share Quiz – Reactions and

BalancingF9 1/25 1/25 TOMORROW

WS – Mole to Mole

StoichiometryF10 1/29 2/1 TOMORROW

WS – Mole to Mass

StoichiometryF11 1/30 2/1 2/8

Types of Stoichiometry Problems

Mass – Mole Conversions : Given is a mass in grams and the

unknown is an amount in moles.When you are given the mass of one substance and asked to calculate the

amount in moles of another substance in the chemical reaction, the general plan is:

Converting Mass to MolesThe following is a solution plan for problems in

which the given quantity is expressed in grams and the unknown quantity is expressed in moles.

Converting Mass to MolesSample Problem

The first step in the industrial manufacture of nitric acid is the catalytic oxidation of ammonia:

NH3 + O2 → NO + H2O (unbalanced)The reaction is run using 824 g of

NH3 and excess oxygen.a. How many moles of NO are formed?

b. How many moles of H2O are formed?

Converting Mass to MolesSample Problem

The first step in the industrial manufacture of nitric acid is the catalytic oxidation of ammonia:

NH3 + O2 → NO + H2O (unbalanced)The reaction is run using 824 g of NH3 and excess oxygen.

a. How many moles of NO are formed?b. How many moles of H2O are formed?

Given: mass of NH3 = 824 gUnknown: a. amt. of NO produced (in mol)

b. amt. of H2O produced (in mol)

Converting Mass to MolesSample Problem

The first step in the industrial manufacture of nitric acid is the catalytic oxidation of ammonia:

NH3 + O2 → NO + H2O (unbalanced)The reaction is run using 824 g of NH3 and excess oxygen.

a. How many moles of NO are formed?b. How many moles of H2O are formed?

Start with a balanced equation:

4NH3 + 5O2 → 4NO + 6H2O

Two conversion factors are needed to solve part (a) - the molar mass of NH3 and the mole ratio of NO to NH3.

Part (b) starts with the same conversion factor as part (a), but then the mole ratio of H2O to NH3 is used to convert

to the amount in moles of H2O. The first conversion factor in each part is the inverted molar mass of NH3.

Converting Mass to Moles

Use the periodic table to compute the molar mass of NH3.

Converting Mass to Moles

Worksheet

Mass to Mole Stoichiometry