1. Mole Conversion Homework 1)1.39 moles H 2 O 8) 220g CaCl 2 2)134.1 g Li 2 O 9) 72g HCl 3)1.38x10 25 molecules O 2 10) 11.4 g O 2 4)0.56 moles H 2 SO 4 11) 2.8x10 -21 moles Ca 5)8.85x10 23 molecules NH 3 12) 56L H 2 6)106.7 g N 2 I 6 7)5.7x10 22 molecules KMnO 4

3. Percent CompositionPercent Composition  What percentage of an element is in a chemical compound?  Part x 100 Whole  Use Formula Mass  Percent mass of an element—  Mass of an element in 1 mole of a chemical compound

4. Example 1:Example 1: Find the percent composition of hydrochloric acid (HCl).

5. Example 2:Example 2:  Find the percent by mass of magnesium, carbon, and oxygen in magnesium carbonate.

6. Example 3:Example 3:  The formula for DDT is C 14 H 9 Cl 5. What is the percent by mass of carbon, hydrogen, and chlorine in this compound?

7. Example 4:Example 4:  Osteoporosis is a disease caused by low calcium levels in diets. Calcium tablets can be supplements to diets and are either calcium carbonate, calcium sulfate, or calcium phosphate. Based on the percent by mass of calcium in each chemical compound, which tablet is the most efficient dietary supplement for calcium levels?

8. Practice 1)Calculate the mass of zinc in a 30.00g sample of zinc nitrate, Zn(NO 3 ) 2 2)Calculate the mass of silver in 325g of silver cyanide (AgCN) 3)What is the percentage of bromine in calcium bromide (CaBr 2 )? 4)What is the percent composition of sodium carbonate, Na 2 CO 3 ?