Chemical Quantities: The Mole Chapter 7 Assignment & Problem Set

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1 Chemical Quantities: The Mole Name Warm-Ups (Show your work for credit) Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8.

2 Chemical Quantities: The Mole 2 Study Guide: Things You Must Know Vocabulary (know the definition and what it means): mole Avogadro s number representative particle diatomic element gram atomic mass gram molecular mass gram formula mass molar mass molar volume of a gas empirical formula molecular formula percent composition Learning Objectives: chemists count particles using the mole, which is equal to Avogadro s number (6.0 x ). the term particle is a general term referring to atoms, ions, molecules, or formula units. gram atomic mass, gram molecular mass, and gram formula mass are the mass of a mole of atoms, molecules, and formula units respectively expressed in grams rather than amu. gram atomic mass, gram molecular mass, and gram formula mass can all be referred to as molar mass. the molar mass of a substance has one mole, or 6.02 x particles, of that substance. the volume of one mole of any gas at STP is 22.4 L; this called molar volume. Honors: how to determine the density of a gas given molar mass and molar volume. how to calculate the mass, number of particles, and volume (gas) of a substance using mole as a conversion factor (Road Map problems). how to calculate percent composition of a substance given the substance s formula. how to determine the empirical formula of a substance given the substance s percent composition. how to determine the molecular formula of a substance given the substance s empirical formula and molar mass. Key Reference Tables Periodic Table Table A: Standard Temperature and Pressure (STP) Table D: Selected Units Table T: Important Formulas and Equations

3 Chemical Quantities: The Mole 3 Read Chapter 7 (Chemical Quantities) Lab 9: Empirical Formula Determination Regents Tables Table A: Standard Temperature and Pressure Table D: Selected Units Table T: Important Formulas and Equations Warm-ups and problems will be collected before you take the test. Answer all problems in the space provided. For problems involving an equation, carry out the following steps: 1. Write the equation. 2. Substitute numbers and units. 3. Show the final answer with units. There is no credit without showing work. Representative Particles 1. Complete the following table. Substance Type of Particle (molecule, formula unit, atom, ion) Chemical Formula Number of Particles in 1 Mole (include units) Example: water molecule H 2O 6.02 x molecules carbon dioxide atomic hydrogen carbonate ion neon gas hydrogen gas sodium chloride 2. Name the representative particle (atom (atom), molecule (mlc), or formula unit (fu)) of each substance. a. oxygen gas b. sodium sulfide c. sulfur dioxide d. potassium 3. How many oxygen atoms are present in a representative particle of ammonium nitrate NH 4NO 3? 4. How many hydrogen atoms are in a representative particle of Al(OH) 3? Number of Particles in a Mole 5. How many molecules are there in 1.3 moles of CO 2? 6. How many moles are 1.7 x atoms of barium? 7. How many moles of NaCl are there in 4.6 x formula units of NaCl? 8. How many oxygen molecules are there in 0.72 moles of oxygen gas? 9. How many oxygen atoms are there in 0.72 moles of oxygen gas?

4 Chemical Quantities: The Mole How many atoms are there in 1.13 mol SO 3? Molar Mass 11. What is the molar mass (gram molecular mass) of C 3H 7OH? 12. What is the mass of 1.00 mol of each substance? a. chlorine gas b. nitrogen dioxide 13. Find the molar mass (gram formula mass) of a. Ca(OH) 2 b. CaCO How many moles is each of a. 15.5g SiO 2 b g AgCl 15. Find the mass of a mol C 5H 12 b mol Ca(CN) 2 Molar Volume of a Gas 16. What is the volume in liters at STP of mol CH 4? 17. Assuming STP, how many moles are in 67.2L SO 2? 18. Calculate the volume of the following gases at STP a.7.6 mol Ar b mol C 2H Honors Dry air is about 20.95% oxygen by volume. Assuming STP, how many oxygen molecules are in a 75.0g sample of air? The density of air is 1.19g/L.

5 Chemical Quantities: The Mole 5 No. of Particles THE MOLE ROAD MAP Volume (Gas only) 6.02x10 23 particles = 1 mol MOLE 22.4 L = 1 mol (at STP) 1molar mass = 1 mol (look it up!) Mass 20. Calculate the number of molecules in 60.0 g NO Calculate the mass in grams of 18.0 L CH 4 (STP). 22. Find the volume in liters of 835g SO 3 at STP. 23. Calculate the volume in milliliters of 3.24 x molecules Cl 2 (STP). 24. How many molecules are there in 150 g of CBr 4? 25. How many grams are in 5.2 x formula units of aluminum chloride? 26. How many grams of propane (C 3H 8) are there in 92 L of propane gas at STP?

6 Chemical Quantities: The Mole 6 Gas Density 27. Honors What is the density of krypton gas at STP? 28. Honors What is the density of NO 2 at STP? 29. Honors The density of a certain gas is 1.96 g/l. What is the molar mass of this gas? Could this gas be N 2O? 30. Honors A gaseous compound composed of sulfur and oxygen that is linked to the formation of acid rain has a density of 3.58 g/l at STP. What is the molar mass of this gas? Percent Composition g Ag combine completely with 4.30g S to form a compound. What is the percent composition of this compound? 32. Calculate the percent composition of ethane(c 2H 6). 33. Calculate the mass of hydrogen in 350g C 2H Calculate the number of grams of S in 3.54g H 2S. 35. Calculate the percent composition of calcium acetate (Ca(C 2H 3O 2) 2).

7 Chemical Quantities: The Mole 7 Empirical Formula 36. Classify each formula as an empirical (E) or a molecular (M) formula. a. S 2Cl 2 b. Na 2SO 3 c. C 17H 19NO 3 d. C 6H 10O 4 e. C 5H 10O 5 f. (NH 4) 2CO Calculate the empirical formula of an compound that is 79.8% C and 20.2% H. 38. The composition methyl butanoate smells like apples. Its percent composition is 58.8% C, 9.8% H, and 31.4% O. Methyl butanoate's molar mass is 102 g/mol, what is its molecular formula? 39. What is the molecular formula for a compound with the composition 40.0% C, 6.6% H and 53.4% O and molar mass = 120g? Review 40. How many protons, electrons, and neutrons are in each isotope? a. zirconium-90 b. palladium-108 c. bromine Convert 2.7 x 10 3 cm/s to km/hr. 42. Name these compounds. a. Fe(OH) 3 b. Na 2CO 3 c. NH 4I d. CCl Write the formulas for a. potassium nitrate b. copper(ii) oxide 44. Honors The element gold has properties that have made it much sought after through the ages. A cubic meter of ocean water has 6 x 10-6 g gold. If the total mass of the water in Earth's oceans is 4 x kg, how many kilograms of gold are distributed throughout the oceans.

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