1 / 11

Moles and Compounds

Moles and Compounds. Chemistry Ch.11 Lesson 2. Moles of Compounds. Chemical formulas are used to determine the number of each atom that make up a compound. Chemical formulas can also be used to determine the number of moles of each type of atom that make up a compound.

starr
Télécharger la présentation

Moles and Compounds

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Moles and Compounds Chemistry Ch.11 Lesson 2

  2. Moles of Compounds • Chemical formulas are used to determine the number of each atom that make up a compound. • Chemical formulas can also be used to determine the number of moles of each type of atom that make up a compound. • The subscripts that identify the number of atoms in a compound can also be used to identify the number of moles.

  3. Practice Problems • Determine the number of moles of chlorine ions in 2.50 molZnCl. • Calculate the number of moles of each element in 1.25 mol glucose (C6H12O6). • Determine the number of moles of sulfate ions present in 3.00 mol iron (III) sulfate (Fe2(SO4)3). • How many moles of oxygen atoms are present in 5.00 mole diphosphoruspentoxide (P2O5)?

  4. Molar Mass of Compounds • The mass of a mole of a compound equals the sum of the mass of every particle that makes up the compound. • Use the information given by the chemical formula to determine the molar mass of a compound. • Number of moles x molar mass = number of grams. • Example Potassium chromate (K2CrO4) 2 moles potassium: 2 x 39.1 g = 78.2 g 1 mole chromium: 1 x 52.0 g = 52.0 g 4 moles oxygen: 4 x 16.0 g = 64.0 g Total: 194.2 g = molar mass of Potassium chromate

  5. Practice Problems • What is the mass of 3.25 moles of sulfuric acid (H2SO4)? • What is the mass of 4.35 x10-2 moles of zinc chloride (ZnCl2)? • How many grams of potassium permanganate (K2MnO4) are in 2.55 moles?

  6. Converting the Mass of a Compound to Moles • Determine the molar mass of each element in the compound; add them together to get the molar mass of the compound. • Divide the mass of the sample by the molar mass of the compound.

  7. Practice Problems • Determine the number of moles present in each of the following: • 22.6 g AgNO3 • 6.50 g ZnSO4 • 35.0 g HCl • 25.0 g Fe2O3 • 254 g PbCl4

  8. Converting Mass of a Compound to Number of Particles • Determine the molar mass of the compound. • Use the molar mass to determine the number of moles of the compound. • Multiply the number of moles of the compound by Avogadro’s number (6.02 x1023). • Multiply the number of each element to the previous answer. • To determine the mass of one formula unit, divide the molar mass by Avogadro’s number (6.02 x1023).

  9. Practice Problems • A sample of silver chromate (Ag2CrO4) has a mass of 25.8 g. • How many silver ions are present? • How many chromate ions are present? • What is the mass of one formula unit of silver chromate? • A sample of ethanol (C2H5OH) has a mass of 45.6 g. • How many carbon atoms does the sample contain? • How many hydrogen atoms does it contain? • How many oxygen atoms does it contain?

  10. Percent Composition • Determine the percent composition by dividing the mass ofthe element by the mass of the compound. • Multiply the number of moles by the molar mass to determine the mass. • Divide the mass of the element by the mass of the compound.

  11. Practice Problems • Determine the percent by mass of each element in calcium chloride. • Calculate the percent composition of sodium sulfate. • Which as a larger percent by mass of sulfur: H2SO3or H2S2O8? • What is the percent composition of phosphoric acid (H3PO4)?

More Related