Unit 10 - Stoichiometry Review

Miscellaneous

100

What is the first step you take when doing stoichiometry?

What is write the balanced equation.

200

What is the equation to determine the percent composition of an element in a compound?

Part (mass of element)/Whole (GFM of compound) x 100

300

Describe the difference between an empirical formula and molecular formula.

Empirical: A formula that represents the simplest ratio in which atoms combine to form a compound

Molecular: A formula giving the number of atoms of each of the elements present in one molecule of a specific compound.

400

How many molecules are there in 3 moles of NaCl?

 1.807 x 10²⁴ molecules

500

What is the percent composition of O in C₆H₁₂O₆?

About 53.28%

Conversions

100

What do you use when trying to find when you convert moles to moles?

The Mole Ratio

200

What are you trying to find when you convert moles to grams?

What is Molar Mass.

300

Fe+O₂ -->Fe₂O₃ 

Find the mole ratio of Iron to Oxygen

4:3

400

What is the gram formula mass of MgCl₂·5H₂O

185.29 g/mol

500

4Al + 3O₂  →  2Al₂O₃

How many moles of Al will be produced from 4 moles of O₂?

5.33 moles

Definitions

100

Mass relationships between substances in a chemical reaction.

What is Stoichiometry.

200

What is indicated by the coefficients in a balanced equation?

The number of moles of a substance.

300

How do gram formula mass and atomic mass relate to one another? What are each of their units?

They are the same thing. Atomic mass is reported in units amu, while gram formula mass is g/mol.

400

What is the molar mass of sodium carbonate (Na₂CO₃)? Describe what molar mass is.

106.0 g/mol

The molar mass of a substance is the mass of one mole of its particles (atoms, molecules, or formula units), expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in the chemical formula.

500

How do you find the empirical formula of a compound?

a. If given % assume a 100g sample and change % value to grams

b.Convert grams to moles

c.Divide the number of moles by the smallest number in mole ratio.

d.If any of the subscripts is a decimal, multiply subscripts by a different number to get all whole-number subscripts

Mole Island

100

when is 22.4 used?

What is liters/mol at stp

200

What is 6.022x10^23?

Avogadros number

300

What do you need to convert moles to grams?

Multiply by the molar mass

400

How do you convert moles to particles?

Multiply the number of moles by Avogadro's number.

500

How many moles are there in H₂O when given 1.5 x 10²³ molecules?

0.249 moles

Practice Mole Problems

100

Fe₃O₄ + 4CO -->3Fe + 4CO₂

How many moles of CO are needed to react with 16.5 g of Fe₃O₄

0.285 moles CO

200

How many moles of Fe₂O₃ will form from 5.0 moles of Fe?

Fe + O₂  -> Fe₂O₃

2.5 moles Fe₂O₃

300

How many moles of KClO₃ must decompose in order to produce 9 moles of oxygen gas?

KClO₃ -> KCl + O₂

6 moles KClO₃

400

How many grams of NaCl will be produced from 1.25 mol of chlorine gas reacting with sodium?

146 g NaCl

500

Ammonium nitrate decomposes into dinitrogen monoxide gas and water. Determine the amount of water produced if 25.0 g of ammonium nitrate decomposes.

NH₄NO₃→N₂O+2H₂O

What is 11.3 grams H₂O