e) How many atoms of nitrogen are in 1.2 g aspartame? #11 HC 4 of 4

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1 Ch. 3 Honors Chem HW #11 HC 1 of 4 A2) An element is a mixture of two isotopes. One isotope of the element has an atomic mass of amu and has a relative abundance of 75.53%. The other isotope has an atomic mass of amu. Calculate the average atomic mass and identify the element. A4) The element europium exists in nature in two isotopes. 151 Eu has a mass of amu and 153 Eu has a mass of amu. The average atomic mass of europium is amu. Calculate the relative abundance of the two europium isotopes.

2 B12) Aspartame, C 14 H 18 N 2 O 5, is an artificial sweetener that is 160 times sweeter than sucrose (table sugar) when dissolved in water. a) Calculate the molar mass of aspartame. b) How many moles are present in 10.0 g of aspartame? c) How many grams are in 1.56 mol of aspartame? d) How many molecules are in 5.0 mg aspartame? e) How many atoms of nitrogen are in 1.2 g aspartame? #11 HC 4 of 4

3 f) How many grams are in 1.0 X10 9 molecules of aspartame? b) C 4 H 6 O 2 (methyl acrylate, from which Plexiglas is made)

4 C4) Calculate the mass percent of carbon for each of the following substances and #12 HC 3 of 5 then arrange the substances in order of increasing mass percent of carbon. Caffeine, C 8 H 10 N 4 O 2 Sucrose, C 12 H 22 O 11 Ethanol, C 2 H 5 OH C5) Vitamin B 12, cyanocobalamin, is essential for human nutrition. Since vitamin B 12 is in animal tissue, but not in higher plants, vegetarians may become deficient in vitamin B 12. Cyanocobalamin contains 4.34% cobalt by mass. Calculate the molar mass of cyanocobalamin, if there is one cobalt atom in each molecule of cyanocobalamin.

5 D1) Give the empirical formula for each of the following compounds. #12 HC 4 of 5 a) vitamin C, C 6 H 8 O 6 b) benzene, C 6 H 6 c) acetylene, C 2 H 2 d) phosphorus pentoxide, P 4 O 10 e) glucose, C 6 H 12 O 6 f) acetic acid, HC 2 H 3 O 2 D4) The compound adrenalin contains 56.79% C, 6.56% H, 28.37% O and 8.28% N by mass. What is the empirical formula for adrenaline?

6 D6) A compound that contains only nitrogen and oxygen is 30.4% N by mass. #12 HC 5 of 5 The molar mass of the compound is 92 g/mol. What is the empirical formula of the compound? What is the molecular formula of the compound? C6) Fungal laccase, a blue protein found in wood-rotting fungi is 0.390% Cu by mass. #13 HC 1 of 6 If a fungal laccase molecule contains 4 copper atom, what is the molar mass of fungal laccase?

7 H2) Find the formula of the following hydrates: a) g MgSO 3 and g H 2 O c) 76.9 % CaSO 3 and 23.1 % H 2 O #13 HC 3 of 6 b) Al(OH) 3(s) + HCl (aq) AlCl 3(aq) + H 2 O (l) double displacement

8 b) C 6 H 6(l) + O 2(g) CO 2(g) + H 2 O (g) #14 HC 2 of 7 combustion

9 e) FeO (s) + O 2(g) Fe 2 O 3(s) Synthesis #14 HC 4 of 7 E5) Balance the following equations and state the type: a) Cr(s) + S 8(s) Cr 2 S 3(s) synthesis b) heat + NaHCO 3(s) Na 2 CO 3(s) + CO 2(g) + H 2 O (g)

10 (The heat can be ignored.) decomposition d) Eu (s) + HF (g) EuF 3(s) + H 2(g) #14 HC 5 of 7 single displacement

11 F2) The compound cisplatin, Pt(NH 3 ) 2 Cl 2, has been studied extensively as an antitumor agent. Cisplatin is synthesized as follows: K 2 PtCl 4(aq) + 2 NH 3(aq) Pt(NH 3 ) 2 Cl 2(s) + 2 KCl (aq) a) What mass of cisplatin, Pt(NH 3 ) 2 Cl 2, can be made from 100. g of K 2 PtCl 4? b) What mass of KCl can be made from 100. g of K 2 PtCl 4? G1) When a mixture of silver metal and sulfur is heated, silver sulfide is formed: #15 HC 2 of 3 heat + 16 Ag (s) + S 8(s) 8 Ag 2 S (s) a) What mass of Ag 2 S is produced from a mixture of 2.0 g Ag and 2.0 g S 8?

12 b) What mass of which reactant is left unreacted? G2) Mercury and bromine will react with each other to produce mercury II bromide: #15 HC 3 of 3 Hg (l) + Br 2(l) HgBr 2(s) a) What mass of HgBr 2 can be produced from the reaction of 10.0g Hg and 9.00 g Br 2? What mass of which reagent is left unreacted?

13 b) What mass of HgBr 2 can be produced from the reaction of 5.00 ml Hg (density = 13.6 g/ml) and 5.00 ml Br 2 (density = 3.10 g/ml)? G6) Aluminum burns in bromine, producing aluminum bromide: #16 HC 1 of 3 2 Al (s) + 3 Br 2(l) 2 AlBr 3(s) In a certain experiment, 6.0 g Al was reacted with an excess of bromine to yield 50.3 g aluminum bromide (experimental yield). Calculate the theoretical and percent yields for this experiment.

14 G7) Consider the following unbalanced reaction: P 4(s) + F 2(g) PF 3(g) How many grams of F 2 are needed to produce 120. g of PF 3, if the reaction has a 78.1% yield? D10) Many homes in rural America are heated by propane gas, a compound that #16 HC 2 of 3 only contains carbon and hydrogen. Complete combustion of a sample of propane produced g of carbon dioxide and g of water as the only products. Find the empirical formula of propane.

15 D13) A compound contains only carbon, hydrogen, and oxygen. #16 HC 3 of 3 Combustion of mg of the compound yields mg CO 2 and 4.37 mg H 2 O. The molar mass of the compound is g/mol. What are the empirical and molecular formulas of the compound?

Due: Asst. #19 Ch. 3 Problems: C2c, C6, D4, D5, D2ab, D6. In class: Notes for Asst. #20

Chemistry Assignment Sheet Ch. 3 Stoichiometry In class: Notes for Asst. #18 Due: Asst. #18 Ch. 3 Problems: C2ab, C4, C5, D1. In class: Notes for Asst. #19 Due: Asst. #19 Ch. 3 Problems: C2c, C6, D4, D5,