Mole

1
Mole

• 6.02 x 1023 of whatever is being counted

2
molecules in 1 mole H2O?

• 6.02 x 1023

3
oxygen atoms in 1 mole H2O?

• 6.02 x 1023

4
hydrogen atoms in 1 mole H2O?

• 1.204 x 1024

5
What is the molar mass of H2O?

• 18 grams / mole

6
Molar mass of Fe

• 55.85 grams / mole

7
Atomic mass of Fe

• 55.85 amu

8
of atoms in 2.7 moles of Fe

• 2.7 mol Fe 6.02x1023 atoms 1 mole

1.625x1024 Fe atoms
9
of atoms in 2.7 g of Fe

• 2.7g Fe 1mol Fe 6.02x1023 atoms
  55.85gFe 1 mole

2.91x1022 Fe atoms
10
Composition

• the of the mass that an element contributes to
  the total compound mass.
• 100 element mass compound mass

11

• What is the composition of sodium in table salt
  (NaCl)?

100 23.0 amu 39.3 Na 58.5 amu
12

• What is the composition of carbon in ethanol
  (C2H5OH)?

13

• What is the by mass of hydrogen in water?

100 2(1.0 amu) 11.1 H 2(1) 16amu
14

• A compound with a formula mass of 30 amu
  contains 40.0 carbon. What is the mass of C?

15

• Determine the empirical formula of a compound
  containing 5.75 g Na, 3.5 g N, and 12.0 g O.

16
Determining Empirical Formula

• determine moles of each element
• Divide each answer by smallest value (gives the
  whole number ratio of elements).

17

• A compound is 40.0 C, 6.7 H, and 53.3 O.
  What is its empirical formula?

18
(No Transcript)