3. Monoatomic anions of an element are identified by the element s name. 4. A binary compound is made of two or more different elements.

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1 CHAPTER 7 HOMEWORK 7-1 (pp ) Write true or false for each statement. 1. A chemical formula indicates the relative number of molecules of each kind in a chemical compound. 2. Monoatomic ions are ions formed from a single atom. 3. Monoatomic anions of an element are identified by the element s name. 4. A binary compound is made of two or more different elements. 5 The Stock system is a system for naming chemical elements and their ions. Explain what each chemical formula tells you about the composition of the compound. The first one is done for you. NaNO 3 The subscript 3 refers to the number of oxygen atoms. There are one atom of sodium and one atom of nitrogen for every three atoms of oxygen. AgCl Ba(OH) 2 (NH 4 ) 2 SO 4 1. Which statement is true? a. All main-group elements are able to form ions. b. The total numbers of positive charges and negative charges must be equal in a binary compound. c. The nonmetals of groups 15, 16, and 17 lose electrons to form cations. d. Elements in the d block form ions of only one charge. 2. Why do many main-group elements lose or gain electrons to form ions? a. The elements are unstable and therefore lose electrons. b. Their tendency is to maximize potential energy. c. The elements form covalent bonds, sharing their electrons with other atoms. d. Their tendency is to form a complete outermost octet in a noble-gas configuration.

2 CHAPTER 7 HOMEWORK 7-10 (pp ) Complete each sentence. 1. The symbols of the elements in a compound are represented in 2. The subscripts show 3. For an ionic compound, the compound s formula is usually the same as 4. To calculate the empirical formula, follow these steps: a. b. c. Solve each problem. Show your work. 1. What is the empirical formula for a compound containing 43.38% Na, 11.33% C, and 45.29% O? 2. What is the mass in grams of mol of sucrose, C 12 H 22 O 11? 3. What is the empirical formula of a compound that contains 52.9% aluminum and 47.1% oxygen? 4. Calculate the percent composition of the compound C 2 H 4 O Which statement is true? a. The empirical formula and molecular formula for a given compound are always the same. b. The molecular formula of a substance tells how the atoms in the molecule are connected. c. The molecular formula gives the actual number and types of atoms in the molecule. d. The percent composition of a compound and the molecular weight are not sufficient information to determine the molecular formula. 2. What is the empirical formula of a compound that is 51.4% Cu, 38.8% O, and 9.7% C? a. Cu 5 C 9 O 4 b. CuCO c. CuCO 3 d. Cu 2 C 2 O 6

3 CHAPTER 7 HOMEWORK 7-11 (pp ) Complete each sentence. 1. The percentage composition of a compound is equal to 2. An empirical formula tells 3. a. A compound s molecular formula is numerically equal to its. b. This means that the molecular formula can be determined given a compound s. GRAPHIC ORGANIZER Create a table, chart, or diagram showing how to use molar mass to determine mass of a compound, amount of compound, number of molecules or formula units of a compound, and the mass and amount of an element. Create a flow chart that shows how to convert an empirical formula to a molecular formula. 1. The molar mass of NaSO 2 is 174 g/mol. What is the molecular formula of the compound? a. NaSO 2 b. Na 2 S 2 O 4 c. Na 2 S 2 O 2 d. 2Na 2 S 4 O 2. The molar mass of CH is 78 g/mol. What is the molecular formula for CH? a. C 2 H 2 b. C 3 H 3 c. C 6 H 6 d. CH 6

4 CHAPTER 7 HOMEWORK 7-2 (pp ) Match the symbol with the name that describes it. 1. Br a. nitrate 2. OH b. chlorite 3. NO 2 c. hydroxide 4. NO 3 d. bromide 5. O 2 e. nitrite 6. CN f. ammonium 7. ClO 2 g. oxide 8. NH 4+ h. cyanide GRAPHIC ORGANIZER Complete the chart by supplying the missing information. Name of Compound or Ion Copper(II) ion Bismuth(III) bromide Stannous fluoride Iron(III) cyanide Potassium permanganate Formula of Compound NH 4 + MgF 2 1. Which is the correct formula for a compound made of Sn 2+ and NO 3? a. Sn 2 NO 3 b. Sn(NO 3 ) 2 c. Sn 3 NO 2 d. 2Sn3NO 2. Which is the correct formula for silver chloride? a. Ag + Cl b. 2Ag2Cl c. AgClO d. AgCl S 2

5 CHAPTER 7 HOMEWORK 7-3 (pp ) Write the prefix that corresponds to each number. Try not to use the book. Number Prefix Number Prefix GRAPHIC ORGANIZER Complete the chart by supplying the missing information. Name of Compound Formula of Compound CO 2 Nitrogen dioxide Carbon tetrachloride Ice Diphosphorus pentoxide 1. Which is the correct formula for phosphorus pentafluoride? a. P5F b. PFl 5 c. PF 5 d. PF 2. NaF 6 is the formula for which compound? a. sodium hexafluoride b. sodium pentafluoride c. hexafluoride sodium d. hexasodium fluoride S 2 Cl 2 P 4 O 7 SF 6

6 CHAPTER 7 HOMEWORK 7-4 (pp ) Define. 1. acids 2. binary acid 3. oxyacid 4. salt Write formulas for each of the following compounds. a. hydrofluoric acid b. acetic acid c. chlorous acid d. carbonic acid e. phosphoric acid Write the name of the compound represented by each formula. f. HClO 4 g. HNO 3 h. HNO 2 i. HI j. H 3 PO 4 1. Which of the following is the formula for silicon dioxide? a. S2O b. Si2O c. SO 2 d. SiO 2 2. H 2 SO 3 is the formula for what compound? a. sulfuric acid b. sulfurous acid c. dihydrous sulfuric acid d. hydrosulfuric acid

7 CHAPTER 7 HOMEWORK 7-5 (pp ) Complete each sentence. 1. Oxidation numbers are assigned to the atoms composing a compound or ion in order to 2. The atoms in a pure element have an oxidation number of. 3. The more electronegative element in a binary molecular compound is assigned the number that 4. The algebraic sum of the oxidation numbers in a compound must equal. 5. Oxidation numbers are useful for. GRAPHIC ORGANIZER Create a flow chart to show the steps in assigning an oxidation number to a compound. Use the compound N 2 O 5 as an example. 1. What are the oxidation numbers for the atoms in AlCl 3? a. +3, 1 b. +3, +1 c. 3, 1 d. 3, In a ClO 4 ion, what is the oxidation number of Cl? a. +4 b. 4 c. +5 d. +7

8 CHAPTER 7 HOMEWORK 7-6 (pp ) Determine the oxidation numbers of these compounds and ions. N 2 N 3 N 2 O 3 KNO 3 NH 4 NO 3 K 2 Cr 2 O 7 CO NH 4 ANOTHER Name each compound according to the prefix system. Carbon(IV) iodide Sulfur(VI) oxide Arsenic(III) sulfide Nitrogen(III) chloride Lead(IV) oxide Nitrogen(I) oxide Phosphorus(V) chloride Water 1. Which is the Stock system name of SO 2? a. sulfur dioxide b. sulfur trioxide c. sulfur(iv) oxide d. sulfur(ii) oxide 2. HNO 2 is the formula for which compound? a. hydrogen nitrogen dioxide b. nitrogen(ii) dioxide c. nitrous acid d. ammonium(ii) oxide

9 CHAPTER 7 HOMEWORK 7-7 (pp ) Complete each sentence. Use an additional sheet of paper if necessary. 1. The formula mass of a molecule or ion is. 2. The molar mass of an element is equal to. 3. To calculate the molar mass of a compound, you should. 4. A compound s molar mass is numerically equal to its. How many moles of atoms of each element are there in one mole of each of these compounds? AlCl 3 Cu 2 O Ba(SCN) 2 LiH H 2 SO 4 Calculate the molar mass of each of these compounds. CO 2 SnI 4 NaH 2 PO 4 Hg 2 Cl 2 Ca(C 2 H 3 O 2 ) 2 1. In the compound Al 2 (SO 4 ) 3, there are a. 2 mol Al, 3 mol S, 12 mol O. b. 2 mol Al, 4 mol S, 4 mol O. c. 6 mol Al, 3 mol S, 12 mol O. d. 2 mol Al, 3 mol S, 7 mol O. 2. What is the molar mass of KMnO 4? a g/mol b g/mol c g/mol d g/mol

10 CHAPTER 7 HOMEWORK 7-8 (pp ) Explain how to find the answer to each of the following questions. The first one is done for you. 1. How many molecules are found in a certain sample of a compound? Take the amount of the compound in moles and multiply it by Avogadro s number. 2. Given the amount of a compound in moles, what is the mass of the compound? 3. Given the mass of an element in a sample of a compound, what is the amount of the element in the compound? 4. Given the mass of an element in a compound, how many atoms of the element are in the sample? GRAPHIC ORGANIZER Create a flow chart to show the steps you would need to take to figure out the mass in grams of 9.03 moles of H 2 S. 1. How many moles of H 2 O are in 24.0 g? a x b c d What is the total mass of oxygen in g of Hg 2 SO 4? a g b g c g d x g

11 CHAPTER 7 HOMEWORK 7-9 (pp ) / Answer each question. 1. What is the percentage composition of a compound? 2. How is the mass percentage of an element in a compound calculated? Describe two different ways. 3. Explain how molar mass can be used as a conversion factor. 4. Explain how to calculate the mass in grams of a substance. Solve each problem. Show your work. 1. Find the percentage composition of KCl. 2. Find the percentage composition of SnI Calculate the percentage of silver in silver nitrate, AgNO Calculate the percentage of carbon in methane, CH Calculate the percentage of nitrogen in g of ammonium nitrate, NH 4 NO What is the percentage composition of N 2 O 5? a. 20% N, 50% O b % N, 80.0% O c. 25.9% N, 74.1% O d. none of the above 2. What is the percentage of potassium (K) in 14.8 g of KOH? a. 69.7% b. 28.5% c. 1.78% d. 56.1%