Section 2 lesson 3: Moles and Molar mass

Section 2 lesson 3:

Moles and Molar mass

By Abby Fancsali

Multiple Choice

Which of the following equations represents a decomposition reaction?

• 2Sb + 3I₂ -> 2SbI₃

• 2 HgO -> 2 Hg + O₂

• FeS + 2HCl -> H₂S + FeCl₂

• Zn + H₂SO₄ -> ZnSO₄(aq +H₂

Multiple Choice

The reaction Pb(NO₃)₂ + 2KI -> PbI₂ + 2KNO₃ is what type of reaction?

• double-displacement reaction

• synthesis reaction.

• decomposition reaction.

• combustion reaction.

Fill in the Blanks

Which Element has an atomic mass of 22.9?

Fill in the Blanks

Which Element has an atomic number of 29?

Fill in the Blanks

How many protons does Copper have

What is a Mole?

• A mole: A special unit to express amounts of small items

  • Think of a mole like a descriptor measurement (like one dozen = 12)​

    • 1 mole= 6.022 x 10²³

      • 6.022 x 10²³ is called Avogadro's number

    • Moles can be used to count anything, but We typically use moles to count the number of atoms

• We use the mole to help convert between grams and atoms​

Fill in the Blanks

How many dollars do you have if you have a mole of pennies?

Fill in the Blanks

How many dozen of donuts do you have if you have half a mole of donuts ?

Molar Mass and conversions

• Molar Mass: The mass in grams of one mole of an element or substance

  • Units ar grams/mole

  • The molar mass is equal to the atomic mass of a substance

    • The only thing that changes is the units

      • Atomic mass= amu

      • molar mass = g/mol

• Setting up a mole to gram conversion is the same as any other conversion

  ​

Example problem 1

• Determine the mass in grams of a 3.50 mol sample of Copper

  • Given: 3.50 mol of copper

  • Need: molar mass of Copper

  • mass of copper sample

• Find the mass of copper on your periodic table:

  • In general​: The atomic mass is on the bottom of an elements box

    ​

Fill in the Blanks

What is the molar mass of Copper?

Example problem 1

Fill in the Blanks

Determine the mass in grams of a 3.50 mol sample of Copper

Example problem 2

​What is the mass in grams of 1.00 mol Uranium

• Given information:

  • 1.00 mol Uranium

• Needed information

  • Molar mass of Uranium

  • Mass of 1.00 mol Uranium​

• Step one: Find the mass of Uranium on the Periodic Table

 

Fill in the Blanks

What is the molar mass of Uranium?

Example problem 2

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What is the mass in grams of 1 mole of Uranium?

Example problem 3

What about Compounds?

• The molar mass of a compound is equal to the sum of all the molar masses of the elements that make up the compound

  • Find the molar mass of water

    • For​mula for Water: H₂O

      • 2 hydrogen = 2 * 1=2

      • 1 oxygen = 1* 16= 16

      • H₂O= 2+16=18 g/mol

  • Find the molar mass of Carbon Dioxide

    • Formula for CO₂

      • 1 Carbon= 1*12

      • 2 Oxygen= 2*16

      • CO₂=48 g/mol

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Fill in the Blanks

The formula for Sucrose is C₁₂H₂₂O₁₁. What is the molar mass