Chapter 7 Chemical Quantities 7.3 Calculations Using Molar Mass Learning Goal Given the number of moles of a substance, calculate the mass in grams; given the mass, calculate the number of moles. © 2014 Pearson Education, Inc.

is a useful conversion factor converts moles of a substance to grams Using Molar Mass The molar mass is a useful conversion factor converts moles of a substance to grams converts mass in grams of a substance to moles © 2014 Pearson Education, Inc.

Guide to Calculating Moles from Grams or Grams from Moles © 2014 Pearson Education, Inc.

Silver metal is used in the manufacture of Learning Check Silver metal is used in the manufacture of tableware, mirrors, dental alloys, and jewelry. If the design for a piece of jewelry requires 0.750 mole of silver, how many grams of silver are needed? © 2014 Pearson Education, Inc.

If the design for a piece of jewelry requires Solution If the design for a piece of jewelry requires 0.750 mole of silver, how many grams of silver are needed? Step 1 State the given and needed quantities. Given: 0.750 mole of Ag Need: grams of Ag © 2014 Pearson Education, Inc.

If the design for a piece of jewelry requires Solution If the design for a piece of jewelry requires 0.750 mole of silver, how many grams of silver are needed? Step 2 Write a plan to convert moles to grams. 0.750 mol of Ag grams of Ag Molar Mass © 2014 Pearson Education, Inc.

If the design for a piece of jewelry requires Solution If the design for a piece of jewelry requires 0.750 mole of silver, how many grams of silver are needed? Step 3 Determine the molar mass and write conversion factors. © 2014 Pearson Education, Inc.

If the design for a piece of jewelry requires Solution If the design for a piece of jewelry requires 0.750 mole of silver, how many grams of silver are needed? Step 4 Set up the problem to convert moles to grams (or grams to moles). © 2014 Pearson Education, Inc.

Conversion Factors for Compounds Conversion factors are written for compounds in the same way as those written for elements. © 2014 Pearson Education, Inc.

A box of salt contains 737 g of NaCl. How many Learning Check A box of salt contains 737 g of NaCl. How many moles of NaCl are present in the box? © 2014 Pearson Education, Inc.

A box of salt contains 737 g of NaCl. How many Solution A box of salt contains 737 g of NaCl. How many moles of NaCl are present in the box? Step 1 State the given and needed quantities. Given: 737 g NaCl Need: moles of NaCl © 2014 Pearson Education, Inc.

A box of salt contains 737 g of NaCl. How many Solution A box of salt contains 737 g of NaCl. How many moles of NaCl are present in the box? Step 2 Write a plan to convert grams to moles. grams of NaCl moles of NaCl Molar Mass © 2014 Pearson Education, Inc.

A box of salt contains 737 g of NaCl. How many Solution A box of salt contains 737 g of NaCl. How many moles of NaCl are present in the box? Step 3 Determine the molar mass and write conversion factors. (1 × 22.99) + 1(35.45) = 58.44 g/mol © 2014 Pearson Education, Inc.

A box of salt contains 737 g of NaCl. How many Solution A box of salt contains 737 g of NaCl. How many moles of NaCl are present in the box? Step 4 Set up the problem to convert grams to moles. © 2014 Pearson Education, Inc.

Summary of Conversions © 2014 Pearson Education, Inc.

Converting Mass to Molecules Moles of element or compound Molar Mass g/mol Avogadro’s Number Grams of element or compound Atoms of element or molecules of compound © 2014 Pearson Education, Inc.

Guide to Calculating Particles from Mass © 2014 Pearson Education, Inc.

A 10.00-lb bag of table sugar contains 4536 g of Learning Check A 10.00-lb bag of table sugar contains 4536 g of sucrose, C12H22O11. How many molecules of sucrose are present? © 2014 Pearson Education, Inc.

A 10.00-lb bag of table sugar contains 4536 g of Solution A 10.00-lb bag of table sugar contains 4536 g of sucrose, C12H22O11. How many molecules of sucrose are present? Step 1 State the given and needed quantities. Given: 4536 g sucrose, C12H22O11 Need: molecules of sucrose © 2014 Pearson Education, Inc.

A 10.00-lb bag of table sugar contains 4536 g of Solution A 10.00-lb bag of table sugar contains 4536 g of sucrose, C12H22O11. How many molecules of sucrose are present? Step 2 Write a plan to convert grams to particles. Molar Mass Avogadro’s Number molecules of sucrose grams of sucrose moles of sucrose © 2014 Pearson Education, Inc.

A 10.00-lb bag of table sugar contains 4536 g of Solution A 10.00-lb bag of table sugar contains 4536 g of sucrose, C12H22O11. How many molecules of sucrose are present? Step 3 Write the equalities and conversion factors. © 2014 Pearson Education, Inc.

A 10.00-lb bag of table sugar contains 4536 g of Solution A 10.00-lb bag of table sugar contains 4536 g of sucrose, C12H22O11. How many molecules of sucrose are present? Step 4 Set up the problem to convert grams to particles. © 2014 Pearson Education, Inc.