Name Class Date. mass of lithium 534 g Li molar mass of lithium 6.94 g/mol Li Unknown:

Size: px

Start display at page:

Download "Name Class Date. mass of lithium 534 g Li molar mass of lithium 6.94 g/mol Li Unknown:"

Kelly Underwood
6 years ago
Views:

1 Skills Worksheet Math Skills Converting Mass to Amount After you study each sample problem and solution, work out the practice problems on a separate sheet of paper. Write your answers in the spaces provided. Problem Lithium (molar mass 6.94 g/mol) is so light that a m 3 (1 L) volume of it has a mass of only 534 g. What is the amount in moles represented by this mass of lithium? Solution Step 1: List the given and unknown values. Given: mass of lithium 534 g Li molar mass of lithium 6.94 g/mol Li Unknown: amount of lithium? mol Step 2: Write down the conversion factor that converts grams to moles. The conversion factor you choose should have what you are trying to find (moles of Li) in the numerator and what you want to cancel (grams of Li) in the denominator. 1 mol Li 6.94 g Li Step 3: Multiply the mass of lithium in grams by this conversion factor, and solve. 1 mol Li 534 g Li 76.9 mol Li 6.94 g Li Practice 1. The price of gold (molar mass g/mol) has varied so much over the last 30 years that with $100 you could buy as much as 2.6 troy ounces (81 g) of gold or as little as 0.13 troy ounces (4.0 g). Calculate the amount in moles that these two masses of gold represent. 2. Aluminum (molar mass g/mol) is the most common metal in Earth s crust. But before the discovery in 1886 of the process that allowed it to be cheaply extracted from bauxite, aluminum was expensive to process. In 1852, a pound of aluminum cost $545; in 1887 the price was $0.30. At those prices, $100 would buy only 83.2 g of aluminum in 1852 but g in Determine the amount in moles that these two masses of aluminum represent. Holt Science Spectrum 18 Atoms and the Periodic Table

2 Skills Worksheets Math Skills Converting Amount to Mass After you study each sample problem and solution, work out the practice problems on a separate sheet of paper. Write your answers in the spaces provided. Problem Hydrogen (molar mass 2.02 g/mol) is the most common element in the universe, and it is usually found in the molecular form H 2. Determine the mass in grams of 7.50 mol of molecular hydrogen. Solution Step 1: List the given and unknown values. Given: amount of hydrogen 7.50 mol H 2 molar mass of hydrogen 2.02 g/mol H 2 Unknown: mass of hydrogen? g Step 2: Write down the conversion factor that converts moles of molecular hydrogen to grams. The conversion factor you choose should have what you are trying to find (grams of H 2 ) in the numerator and what you want to cancel (moles of H 2 ) in the denominator g H 2 1 mol H 2 Step 3: Multiply the amount of hydrogen in moles by the conversion factor you have chosen, and solve. Practice 7.55 mol H g H 2 1 mol H g H 2 1. Uranium (molar mass g/mol) has the largest molar mass of any element naturally found on Earth. What is the mass of 7.50 mol of uranium? 2. Ruthenium ( g/mol) is used as a catalyst and to improve titanium s resistance to corrosion. It is also one of the rarest elements in Earth s crust, making up less than one ten-millionth of the crust s mass. Calculate the mass of 37.0 mol of ruthenium. Holt Science Spectrum 16 Atoms and the Periodic Table

3 Math Skills continued 3. Large deposits of manganese (54.94 g/mol), a metal used to form many different types of alloys, have been found on the floors of oceans and large lakes. Suppose one of these deposits contains 383 mol of manganese. What is the mass of the manganese deposit? 4. Sodium chloride (58.44 g/mol), commonly known as table salt, is the most common type of salt. What is the mass of 29.0 mol of sodium chloride? 5. Oxygen gas is most often found as O 2 (molar mass g/mol). However, under certain conditions, a compound called ozone, O 3 (molar mass g/mol), is formed. Ozone, which is highly reactive and unstable, is formed when O 2 is exposed to ultraviolet radiation. Ozone is able to absorb other ultraviolet radiation, protecting life on Earth s surface from this harmful radiation. a. What is the mass of 17 mol of O 2? b. What is the mass of 17 mol of O 3? 6. After oxygen, silicon is the most common element found in Earth s crust. Both elements are found in silicon dioxide (molar mass g/mol), which is the main component in sand. Suppose you have 893 mol of silicon dioxide in a sample of sand. What is the mass of the silicon dioxide? 7. Carbon dioxide (molar mass g/mol) is an inert gas that plants need for photosynthesis. a. Calculate the mass of 893 mol of carbon dioxide. b. How does the mass you obtained in part (a) compare with the mass of 893 mol of silicon dioxide? 8. Both marble and limestone contain the same mineral, calcite, which consists of the compound calcium carbonate (molar mass g/mol). What is the mass of a block of calcite if it contains 37 mol of calcium carbonate? Holt Science Spectrum 17 Atoms and the Periodic Table

4 Math Skills continued 3. Osmium (molar mass g/mol) and iridium (molar mass g/mol) have the highest densities of any elements. A cubic centimeter of either element has a mass of around 22.6 g. Determine the amount in moles of 22.6 g of each element. 4. Tungsten (molar mass g/mol), whose high melting point makes it suitable for light bulb filaments and certain types of steel, is one of the heavier elements; its name even means heavy stone in Swedish. What is the amount in moles contained in a g sample of tungsten? 5. Carbon (molar mass g/mol) and lead (molar mass g/mol) are the lightest and heaviest members of their elemental group, respectively. Determine the amount in moles represented by 245 g of carbon and by 245 g of lead. 6. Potassium chloride (molar mass g/mol) is a fairly common salt. Although it is fatal in high doses, potassium chloride can be safely consumed in small quantities. It is often mixed in small proportions with sodium chloride to produce low sodium table salt. Determine the amount in moles in 150 g of potassium chloride. 7. Sulfur dioxide (molar mass g/mol), which is formed when heated sulfur is oxidized, is a pollutant that irritates lung tissue and makes it more sensitive to dust and other particles inhaled from the outside air. Determine the amount in moles that would be represented by 27 kg of sulfur dioxide. 8. Aluminum quickly oxidizes when it is exposed to air, so there is always a thin layer of aluminum oxide (molar mass g/mol) on any aluminum surface. This oxide layer protects the aluminum from further corrosion. If the aluminum oxide on several aluminum surfaces has a mass of 79 g, what amount in moles would be represented by this mass? 9. Sulfuric acid (molar mass g/mol) is widely used as a corrosive reactant. It is also used in making fertilizer, detergents, drugs, explosives, and paints, and in the production of other chemicals. The usefulness of sulfuric acid is so great that it is the most widely produced chemical in the United States. What is the amount in moles in a sample of sulfuric acid that has a mass of 165 g? Holt Science Spectrum 19 Atoms and the Periodic Table

5 TEACHER RESOURCE PAGE number 11. of boxes chandeliers bulbs per chandelier bulbs per box number of boxes (75 chandeliers) 12 bulbs/ chandelier (4 bulbs/box) boxes sodium chloride mass ( kg seawater) sodium chloride mass g sodium chloride kg 60 min hour hour seawater mass mass sodium chloride per kilogram sea water g sodium chloride kg sea water 60 s 3600 s min 45 min 60 s 2700 s min time 6300 s film length ( time) frames per length per second frame film length (6300 s) (24 frames/s)(1.9 cm/frame) film length cm m 2.9 km 14. volume columns volume per column (46 columns) volume (3.14)(0.95 m) 2 (10.4 m) m volume 3 CONVERTING AMOUNT TO MASS mol U g U 1790 g U 1 mol U mol Ru g Ru 1 mol Ru g Ru mol Mn g 1 mol Mn g Mn mol NaCl g 1 mol NaCl g NaCl 5. a. 17 mol O g O 2 1 mol O g O 2 b. 17 mol O g O 3 1 mol O g O mol SiO g SiO 2 1 mol SiO g SiO 2 7. a. 893 mol CO g CO 2 1 mol CO g CO 2 b. Mass of CO 2 is less mol CaCO g CaCO 3 1 mol CaCO g CaCO 3 CONVERTING MASS TO AMOUNT g Au 1 mol Au 0.41 mol Au g Au 4.0 g Au 1 mol Au g Au mol Au g Al 1 mol Al 3.08 mol Al g Al g Al 1 mol Al g Al mol Al g Os 1 mol Os g Os mol Os 22.6 g Ir 1 mol Ir mol Ir g Ir Holt Science Spectrum 96 Atoms and the Periodic Table

THE PERIODIC TABLE. Chapter 15

THE PERIODIC TABLE. Chapter 15 THE PERIODIC TABLE Chapter 15 MENDELEEV 1869 The first version of the periodic table was published by Dmitri Mendeleev, a Russian chemist He arranged the elements in order of increasing atomic mass This