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NIS – CHEMISTRY

NIS – CHEMISTRY. Lecture 54 – Lecture 55 Moles of Compounds Ozgur Unal. Chemical Formulas and the Mole. A chemical formula indicates the numbers and types of atoms contained in one unit of the compound. Example: NaCl or Mg(NO3)2 etc. 1 NaCl contains 1 Na atom and 1 Cl atom

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NIS – CHEMISTRY

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  1. NIS – CHEMISTRY Lecture 54 – Lecture 55 Moles of Compounds OzgurUnal

  2. Chemical Formulas and the Mole A chemical formula indicates the numbers and types of atoms contained in one unit of the compound. Example: NaCl or Mg(NO3)2 etc. 1 NaCl contains 1 Na atom and 1 Cl atom 1 Mg(NO3)2 contains 1 Mg atom, 2 N atoms and 6 O atoms • How about moles of compounds? • How many moles of Cl- are there in 1 mole of NaCl? • How many moles of Na+ are there in 3 moles of NaCl? • How many moles of N are there in 1 mole of Mg(NO3)2? • How many moles of O are there in 2 moles of Mg(NO3)2?

  3. Chemical Formulas and the Mole Example: Zinc chloride is used in soldering flux, an alloy used to join two metals together. Determine the moles of Cl- ions in 2.5 mol ZnCl2. • Example: Plants and animals depend on glucose C6H12O6 as an energy source. Calculate the number of moles of each element in 1.25 mol C6H12O6.

  4. The Molar Mass of Compounds The mass of your backpack is the sum of the pack and the masses of the books, notebooks, pencils and other items. Similarly, the molar mass of a compound is the sum of the molar masses of the elements in the compound. Example: Molar mass of K2CrO4 Molar mass of K: 39.1 g/mol Molar mass of Cr: 52.0 g/mol Molar mass of O: 16.0 g/mol Molar mass of K2CrO4: 2*K + Cr + 4*O = 194.2 g/mol • Example: Determine the molar mass of each compound below: • CaCl2 C2H5OH KC2H2O2

  5. Converting Moles of a Compound to Mass Example: The characteristic odor of garlic is due to allyl sulfide, (C3H5)2S. What is the mass of 2.5 mol of (C3H5)2S? • Example: The United States chemical industry produces more sulfuric acid (H2SO4), in terms of mass than any other chemical. What is the mass of 3.25 mol of H2SO4?

  6. Converting the Mass of a Compound to Moles Example: Calcium hydroxide is used to remove sulfur dioxide from the exhaust gases emitted by power plants and for softening water by the elimination of Ca+2 and Mg+2 ions. Calculate the number of moles of calcium hydroxide in 325 g of the compound. • Example: Determine the number of moles present in each compound: • 22.6 g AgNO3 • 6.5 g ZnSO4

  7. Converting the Mass of a Compound to Number of Particles • Example: AlCl3 is used in refining petroleum and manufacturing rubber and lubricants. A sample of AlCl3 has a mass of 35.6 g. • How many Al atoms does the sample contain? • How many Cl atoms are present? • Example: Ethanol C2H5OH, a domestically produced fuel source in the US, is often blended with gasoline. A sample of ethanol has a mass of 45.6 g. • How many C atoms does the sample contain? • How many H atoms are present? • How many O atoms are present?

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