11 24 What Is Molar Mass

Launch: 11/24   Grab you binder and immediately take a seat!

1.  What is a mole?

2.  What is Avogadro’s number?

3.  How is a mole defined? (Hint: use the word carbon)

Launch 11/24 5.  How many moles are there in 6g of carbon-12?

a.  .5 moles b.  1 mole

c.  2 moles d.  12 moles

Announcements   This is a really important week!

  Points end tomorrow   Block 5 is in the lead   Be engaged   Be respectful

What is molar mass? Mr. Heffner 11/24/09

What is a molar mass?   Molar mass is…

  the sum of all of the atomic masses in a molecule

5

B Boron 10.81 Atomic

mass


  the sum of the atomic masses in a molecule

H2O Molar mass = mass of H + mass of H + mass of O = 1.01 + 1.01 + 16.00

= 18.02 g/mol Units!



NH3 Molar mass = mass of N + mass of H + mass of H + mass of H

= mass of N + 3X(mass of H)

= 14.01 + 3X(1.01) = 14.01 + 3.03




C2H2 Molar mass = mass of C + mass of C + mass of H + mass of H

= 2X(mass of C) + 2X(mass of H)

= 2X(12.01) + 2X(1.01) = 24.02 + 2.02



  the sum of all of the atomic masses in a molecule   a.k.a molecular mass or molecular weight

  basically, how much 1 mole of a molecule weighs

Whiteboards   Work in pairs

  Trade-off marker every question

  You have 60 seconds to draw the answer   Show all of your work!   Don’t forget units!

  Lift board only when prompted

What is the molar mass of of fluorine (F)?

What is the molecular mass of O2?

What is the molecular mass of CH4?

What is the molecular weight of SOCl2?

What is the molar mass of Ca(OH)2?

What is the molecular weight of CH2COOH?

Practice Questions   Practice question worksheet

Exit Slip 1.  Molar mass is

a.  a number with the units g/meters b.  the number of molecules in a gram of a substance

c.  the sum of all of the atomic masses in a molecule d.  calculated by adding up the atomic numbers in a

molecule

Exit Slip 2.  Molar mass is also called

a.  molecular mass b.  molecular weight

c.  molar weight d.  both a & b

Exit Slip 3.  What is the molar mass of oxygen (O)?

a.  1.00 g/mol b.  8.00 g/mol

c.  16.00 g/mol d.  32.00 g/mol

Exit Slip 4.  Which of the following show the correct way to

calculate the molecular weight of CH3OH? a.  12.01 + 3 X (1.01) + 16.00 b.  12.01 + 4 X (1.01) + 16.00 c.  12.01 + 1.01 + 16.00

d.  6.00 + 1.00 + 8.00

Exit Slip 5.  What is the molecular mass of Mg(OH)2

a.  24.31 g/mol b.  41.32 g/mol

c.  58.33 g/mol d.  100 g/mol

Homework   Finish practice questions

Spiritual

11 24 What Is Molar Mass