1. Pick Up a Packet & Calculator Write Down EQ Molar Mass EQ: How is molar mass calculated?

2. Parts of a Formula… You already know this!! Symbols: determine what elements are in the compound Subscripts: determine how many of each element are in the compound Numbers outside the parenthesize are multiplied to every element inside the parenthesize Ex: CO 2 : 1 carbon & 2 oxygen Ex: Mg 3 (PO 4 ) 2 : 3 Magnesium, 2 phosphorus, 8 oxygen

3. How many of each element are in the following compounds?? CH 4  C 3 H 7  Ca(NO 3 ) 2  Ni(OH) 2  (NH 4 ) 2 O  C = 1 H = 4 C= 3 H= 7 Ca= 1 N= 2 O= 6 Ni= 1 O= 2 H= 2 N= 2 H= 8 O= 1

4. Molar Mass What is molar mass? The mass of a compound in grams How is it Calculated? 1 st - determine how many of each element is in the compound 2 nd - multiply the number of each element by its atomic mass (round to a whole number) 3 rd - add them together

5. Example 1 st - CO 2 : 1 carbon & 2 oxygen 2 nd - calculate the mass of each element in the compound C: 12 x 1 = 12 O: 16 x 2 = 32 Step 2: Add them together 12 + 32 =44 Therefore the molar mass of CO 2 is 44 grams

6. Example 1 st - Mg 3 (PO 4 ) 2 : 3 Magnesium, 2 phosphorus, 8 oxygen 2 nd - Mg: 24 x 3 = 72 P: 31 x 2 = 62 O: 16 x 8 = 128 3 rd - 72 + 62 + 128 = 262 g Mg 3 (PO 4 ) 2

7. You try! CH 4  C 3 H 7  Ca(NO 3 ) 2  Ni(OH) 2  (NH 4 ) 2 O  (12 x 1) + (1 x 4) = 16 (12 x 3) + (1 x 7) = 43 (40 x 1) + (14 x 2) + (16 x 6) = 164 (59 x 1) + (16 x 2) + (1 x 2) = 93 (14 x 2) + (1 x 8) + (16 x 1) = 52

8. Percent Composition This is the percent of each element found in the compound To calculate: Take the total mass of the element in the compound and divide it by the total mass of the compound Then multiply by 100 to convert to a percent Ex. C: 12 x 1 = 12  %C = 12/44 =.272 x 100 = 27% O: 16 x 2 = 32  %O = 32/44 =.727 x 100 = 73% Total = 44 Total = 100% Using the previous compounds...lets calculate % composition!