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Chemical Formulas and Chemical Compounds

Chemical Formulas and Chemical Compounds

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Chemical Formulas and Chemical Compounds

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  1. Chemical Formulas and Chemical Compounds Chapter 7 Review – Answers

  2. In a stock name such as iron(III) sulfate, the roman number tells us ____. The result of changing a subscript in a correctly written chemical formula is to _____. C. The charge on each Fe ion C. Change the formula so that it no longer represents the compound it previously represented. Pages 53 - 54

  3. Pages 53 - 54 • The explosive TNT has the molecular formula C7H5(NO2)3. • How many elements make up this compound? • How many oxygen atoms are present in one molecule of C7H5(NO2)3? • How many atoms in total are present in one molecule of C7H5(NO2)3? • How many atoms are present in a sample of 2  1023molecules of C7H5(NO2)3? 4 elements 6 oxygen atoms 21 atoms

  4. Pages 53 - 54 • How many atoms are present in each of these formula units? • Ca(HCO3)2 • C12H22O11 • Fe(ClO2)3 • Fe(ClO3)2 11 atoms 45 atoms 10 atoms 9 atoms

  5. Pages 53 - 54 • (see below) • What is the formula for the compound dinitrogen pentoxide? • What is the Stock name for the covalent compound CS2? N2O5 Carbon disulfide

  6. Pages 53 - 54 • Some binary compounds are ionic, others are covalent. The types of bonding partially depend on the position of the elements in the periodic table. Label each of these claims as True or False; if False, specify the nature of the error. • Covalently bonded binary molecular compounds typically form from nonmetals. True

  7. Pages 53 - 54 • Some binary compounds are ionic, others are covalent. The types of bonding partially depend on the position of the elements in the periodic table. Label each of these claims as True or False; if False, specify the nature of the error. • Binary ionic compound form from metals and nonmetals, typically from opposite sides of the periodic table. True

  8. Pages 53 - 54 • Some binary compounds are ionic, others are covalent. The types of bonding partially depend on the position of the elements in the periodic table. Label each of these claims as True or False; if False, specify the nature of the error. • Binary compound involving metalloids are always ionic. False; metalloids on the right of the stair-step line act as nonmetals in compounds

  9. Pages 53 - 54 • Fill in the blanks in the table below. Al2S3 Al2(SO3)3 Lead(II) chloride Ammonium phosphate

  10. Pages 55 - 56 • Tin has possible oxidation numbers of +2 and +4 and forms two known oxides. One of them has the formula SnO2. • Give the stock name for SnO2. • Give the empirical formula for the other oxide of tin. Tin(IV) oxide SnO

  11. Pages 55 - 56 • Scientists believe that two separate reactions contribute to the depletion of the ozone layer, O3. The first reaction involves oxides of nitrogen. The second involves free chlorine atoms. Both reactions follow. When a compound is not stated as a formula, write the correct formula in the blank beside its name. • _____(nitrogen monoxide) + O3→ ______ (nitrogen dioxide) + O2 • Cl + O3→ ______ (chlorine monoxide) + O2 NO NO2 ClO

  12. Pages 55 - 56 • Consider the covalent dinitrogen trioxide when answering the following: • What is the formula for dinitrogen trioxide? N2O3

  13. Pages 57 - 58 • Label each of the following statements as True or False: • If the formula mass of one molecule is x amu, the molar mass is x g/mol. • Samples of two different chemicals with equal numbers of moles must have equal masses as well. • Samples of two different chemicals with equal numbers of moles must have equal numbers of molecules as well. True False True

  14. Pages 57 - 58 • How many moles of each element are present in a 10.0 mol sample of Ca(NO3)2? 10.0 mol calcium 20.0 mol nitrogen 60.0 mol oxygen

  15. Pages 57 - 58 • Consider a sample of 10.0 g of the gaseous hydrocarbon C3H4 to answer the following questions. • How many moles are present in this sample? • How many molecules are present in the C3H4 sample?

  16. Pages 57 - 58 • Consider a sample of 10.0 g of the gaseous hydrocarbon C3H4 to answer the following questions. • How many carbon atoms are present in this sample? • What is the percentage composition of hydrogen in the sample?

  17. Pages 57 - 58 • The chief source of aluminum metal is the ore alumina, Al2O3. • Determine the percentage composition of Al in this ore. • How many pounds of aluminum can be extracted from 2.0 tons of alumina?

  18. Pages 57 - 58 • Compound A has a molar mass of 20 g/mol, and compound B has a molar mass of 30 g/mol. • What is the mass of 1.0 mol of compound A? • How many moles are present in 5.0 g of compound B? • How many moles of compound B are needed to have the same mass as 6.0 mol of compound A? 20 grams

  19. Pages 59 - 60 • Write empirical formulas to match the following molecular formulas: • C2H6O4 • N2O5 • Hg2Cl2 • C6H12 CH3O2 N2O5 HgCl CH2

  20. Pages 59 - 60 • A certain hydrocarbon has an empirical formula of CH2 and a molar mass of 56.12 g/mol. What is its molecular formula? C4H8

  21. Pages 59 - 60 • A certain ionic compound is found to contain 0.012 mol of sodium, 0.012 mol of sulfur, and 0.018 mol of oxygen. • What is its empirical formula? • Is this compound a sulfate, sulfite, or neither? Na2S2O3 neither

  22. Pages 59 - 60 • Gas X is found to be 24.0% carbon and 76.0% fluorine by mass. • Determine the empirical formula of gas X. CF2

  23. Pages 59 - 60 • Gas X is found to be 24.0% carbon and 76.0% fluorine by mass. • Given that the molar mass of gas X is 200.04 g/mol, determine its molecular formula. C4F8

  24. Pages 59 - 60 • A compound is found to contain 43.2% copper, 24.1% chlorine and 32.7% oxygen by mass. • Determine its empirical formula. CuClO3

  25. Pages 59 - 60 • A compound is found to contain 43.2% copper, 24.1% chlorine and 32.7% oxygen by mass. • What is the correct Stock name of the compound in part a? Copper(I) chlorate

  26. Pages 61 - 64 • Write formulas for the following compounds: • Copper(II) carbonate • Sodium sulfite • Ammonium phosphate • Tin(IV) sulfide CuCO3 Na2SO3 (NH4)3PO4 SnS2

  27. Pages 61 - 64 • Write the Stock names for the following compounds: • Mg(ClO4)2 • Fe(NO3)2 • Fe(NO2)3 • CoO Magnesium perchlorate Iron(II) nitrate Iron(III) nitrite Cobalt(II) oxide

  28. Pages 61 - 64 • (see below) • How many atoms are representd by the formula Ca(HSO4)2? • How many moles of oxygen atoms are in a 0.50 mol sample of this compound? 13 4 mol oxygen

  29. Pages 61 - 64 • Following are samples of four different compounds. Arrange them in order of increasing mass, from smallest to largest. • 25 g of oxygen gas • 1.00 mol of H2O • 3  1023molecules of C2H6 • 2  1023molecules of C2H6O2 c, b, d, a

  30. Pages 61 - 64 • (see below) • What is the formula for sodium hydroxide? • What is the formula mass of sodium hydroxide? • What is the mass in grams of 0.25 mol of sodium hydroxide? NaOH 40 g/mol 10 grams

  31. Pages 61 - 64 • What is the percentage composition of ethane gas, C2H6, to the nearest whole number? • Ribose is an important sugar (part of RNA), with a molar mass of 150.15 g/mol. If its empirical formula is CH2O, what is its molecular formula? 80% carbon, 20% hydrogen C5H10O5

  32. Pages 61 - 64 • Butane gas, C4H10, is often used as a fuel. • What is the mass in grams of 3.00 mol of butane? • How many molecules are present in that 3.00 mol sample? • What is the empirical formula of the gas? 174 grams 1.81  1024 molecules C2H5

  33. Pages 61 - 64 • Napthalene is a soft covalent solid that is often used in mothballs. Its molar mass is 128.18 g/mol and it contains 93.75 % carbon and 6.25 % hydrogen. Determine the molecular formula of napthalene from this data. C10H8

  34. Pages 61 - 64 • Nicotine has the formula CxHyNz. To determine its composition, a sample is burned in excess oxygen, producing the following results: 1.0 mol of CO2 0.70 mol of H2O 0.20 mol of NO2 Assume that all the atoms in nicotine are present as products. • Determine the number of moles of carbon present in the products of this combustion. • Determine the number of moles of hydrogen present in the products of this combustion. • Determine the number of moles of nitrogen present in the products of this combustion. 1.0 mol C 1.4 mol H 0.2 mol N

  35. Pages 61 - 64 • Nicotine has the formula CxHyNz. To determine its composition, a sample is burned in excess oxygen, producing the following results: 1.0 mol of CO2 0.70 mol of H2O 0.20 mol of NO2 Assume that all the atoms in nicotine are present as products. • Determine the empirical formula of nicotine based on your calculations. • In a separate experiment, the molar mass of nicotine is found to be somewhere between 150 and 180 g/mol. Calculate the molar mass of nicotine to the nearest gram. C5H7N 162 g/mol