10 9 8 7 6 5 4 3 2 13/11 Multistep Conversions3/11 Multistep Conversions

1 year = ? min

2. CALCULATE how many minutes are in 1 year by using a “string of conversion” factors. Show all work.

1. Analyze the cookie recipe. If a baker wanted to make 40 cookies how much of the following would they need: eggs? cups of flour?

Make 20 cookies!

The Law of Conservation of ________ and a _______________ equation allows us to calculate how much of substance reacts or is produced in a chemical reaction. These types of calculations are called _____________________ and use _______________ factors to solve for an unknown mass or # of moles. Balance the equation below so we can practice some stoichiometry:

Introduction to StoichiometryIntroduction to Stoichiometry

mass balanced

stoichiometry conversion

Stoi - chi - om - me -tryStoy- key- ahm- meh-tree

The Law of Conservation of ________ and a _______________ equation allows us to calculate how much of substance reacts or is produced in a chemical reaction. These types of calculations are called _____________________ and use _______________ factors to solve for an unknown mass or # of moles. Balance the equation below so we can practice some stoichiometry:

H2 + O2 H2O

mass balanced

stoichiometry conversion

Introduction to StoichiometryIntroduction to Stoichiometry

Formation of WaterFormation of Water

2H2 + 1O2 2H2O

Formation of WaterFormation of Water

2H2 + 1O2 2H2O

Formation of WaterFormation of Water

2H2 + 1O2 2H2O

2 molecules of H2 + 1 molecules of O2 2 molecules of H2O

2 x H2 + 1 x O2 2 x H2Omolemolemole

The coefficients are molar ratios!The balanced equation is like a recipe!

2 x H2 + 1 x O2 2 x H2O(6.022 x 1023)(6.022 x 1023)(6.022 x 1023)

mol H2

How much Oxygen is RequiredHow much Oxygen is Required

If a chemist has ______ g of H2, how many g of O2 would be required for the reaction?

GIVEN INFORMATION

____ H2 ____ H2 ____ H2 ____ O2 ____ O2 ____ O2WHAT I WANT

TO KNOW

10.0

2.0210.0 g H2

g mol mol mol mol g

mol H2

mol O2

2H2 + 1O2 2H2O

132.00

= 79.2 g O2 g H2

121

mol O2

g O2

Mass of a substancein grams

Mass of new substance in grams

Molar mass of original substance

Molar mass of new

substance

Mole ratio from balanced

equation

SO, WE KNOW THAT FOR ______ g H2 TO FULLY REACT, ______ g O2 IS NEEDED.

Mass Mass Mole Conversions Mole Conversions

g mol mol mol

mol g

10.0 79.2

A student sets up the stoichiometry calculation below to find out how much water is made if you start with 200 g of NaOH.

1. WRITE what 3 things they did wrong in their calculation.

_2_ NaOH + _1_ H2SO4 _2_ H2O + _1_ Na2SO4

200 g NaOH

1 mol NaOH200 g NaOH

2 mol NaOH

3 mol H2O 1 mol H2O

18.02 g H2O= 54.06 g H2O

10 9 8 7 6 5 4 3 2 13/6 Stoichiometry Error3/6 Stoichiometry Error