When referring to mass sum of the atomic masses of the atoms represented by the formula of a molecular substance, the correct term used is A. atomic mass B. formula weight C. molecular mass D. molecular weight 12. A mole of CO2 contians A. 6.02 x 1023 ions C. 6.02 x 1023 formula ions B. 6.02 x 1023 molecules D. 6.02 x 1023 atoms 13. The mass of the products in a chemical reaction depends on the amount of A. excess reactant B. limiting reactant C. oxidizing agent D. reducing subtannce 14.
Identify the condensed formula of the following structure: A) (CH3)2CHCHClCH(CH3)2 B) CH3CH(CH3)CHClCH(CH3)2 Ans: C C) D) (CH3)2CHCHClC(CH3)3 (CH3)3CCHClCH(CH3)3 9. What is the chemical formula of the following carbon skeleton diagram? A) C8H14 Ans: C B) C8H16 C) C8H18 D) C8H20 10. How many hydrogen atoms are there on carbon atoms 1 and 2, respectively, in the structure below? A) 4, 1 B) 4, 0 Ans: D C) 3, 1 D) 3, 0 11.
8.1 Multiple-Choice and Bimodal Questions 1) There are __________ paired and __________ unpaired electrons in the Lewis symbol for a phosphorus atom. A) 4, 2 B) 2, 4 C) 2, 3 D) 4, 3 E) 0, 3 Answer: C Diff: 1 Page Ref: Sec. 8.1 2) In the Lewis symbol for a fluorine atom, there are __________ paired and __________ unpaired electrons. A) 4, 2 B) 4,1 C) 2, 5 D) 6, 1 E) 0, 5 Answer: D Diff: 1 Page Ref: Sec. 8.1 3) Based on the octet rule, magnesium most likely forms a __________ ion.
i. What is the hydrogen concentration of a solution with a pOH of 3.7? j. What is the pH of a substance with a hydroxide concentration of 4 x 10-5? k. What is the hydroxide concentration of a substance with a pOH of 8.5?
Moles and empirical formulae 1 Calculate the molar mass of the following: (Relative atomic masses: H = 1; N = 14; O = 16; Na = 23; S = 32; Cl = 35.5; K =39.) (a) nitric acid, HNO3 (b) sodium sulfate, Na2SO4 (c) ammonia, NH3 (d) potassium chloride, KCl (e) chlorine, Cl2 2 John says that there is no change in mass during a chemical reaction. Anna disagrees. She says that when calcium carbonate reacts with hydrochloric acid to form carbon dioxide, calcium chloride and water, the mass of the reaction vessel and contents decreases. Who is right, John or Anna?
b) Write the redox half reactions (one for oxidation, one for reduction). c) Identify the substance being
14.1 Multiple-Choice and Bimodal Questions 1) Consider the following reaction: [pic] The average rate of appearance of B is given by[pic]. Comparing the rate of appearance of B and the rate of disappearance of A, we get [pic] A) -2/3 B) +2/3 C) -3/2 D) +1 E) +3/2 Answer: B Diff: 1 Page Ref: Sec. 14.2 2) Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction: [pic] In a particular experiment at 300 °C, [pic]drops from 0.0100 to 0.00650 M in [pic] The rate of appearance of [pic] for this period is __________ M/s. A) [pic] B) [pic] C) [pic] D) [pic] E) [pic] Answer: A Diff: 1 Page Ref: Sec. 14.2 3) Which substance in the reaction below either appears or disappears the fastest?
To find out how much acid was neutralized by single doses of each antacid we have to subtract the answers from question one from the moles of HCl (.004mol). Maalox: .004 -.001205= .002795 mol Tums: .004 - .00112 = .002880 mol Mylanta: .004 - .001 = .003 mol CVS brand: .004 - .000995 = .003005 mol Rennies: .004 - .00122 = .002780 mol Divide the number of moles of acid neutralized in each case by that antacid's mass. This gives you the moles of acid neutralized per gram of antacid, which will allow you to judge the strongest and weakest antacids on a per weight basis. Maalox: 24.1ml/20.0g = 1.21ml/g .002795 mol base / 20.0g = .00013975 mol base/pill Tums: 22.4ml/21.0g = 1.07ml/g .002880 mol base / 21.0g = .0001371 mol base/pill Mylanta: 20.0ml/18.0g = 1.11ml/g .003 mol base / 18.0g = .0001666 mol base/pill CVS brand: 19.9ml/18.3g = 1.09ml/g (.003005 mol base)/ (18.3g pill) = .0001642 mol base/pill Rennies: 24.4ml/ 17.5g = 1.39ml/g (.002780 mol base)/ (17.5g pill) = .0001588 mol base/pill
Answer E √ A 2. B C Which of the following is an example of an acid / base conjugate pair? A SO3 and HSO3– D HClO4 and ClO4– E 1 H3O+ and OH– C E CH3COOH and CH3CH2COOH B 3. D HNO3 and HNO2 √ The pKa of HCN is 9.21. What is the Kb of its conjugate base, CN–?
Calculations involving Solutions (1) Answer the following questions on file paper. Remember to set out your working neatly and clearly, showing all necessary steps. Give answers to the appropriate number of significant figures. Use Ar values when required as given on your copy of the Periodic Table. 1) Calculate the number of moles in each of the following solutions:- a) 2.0 dm3 of 0.050 mol.dm-3 hydrochloric acid b) 50 dm3 of 5 mol.dm-3 sulfuric acid c) 10 cm3 of 0.25 mol.dm-3 potassium hydroxide [3] 2) Calculate the volume in cm3 of each solution that contains the following numbers of moles:- a) 0.00500 moles of NaOH with concentration 0.100 mol.dm-3 b) 1.00×10-5 moles of HCl with concentration 0.0100 mol.dm-3 c) 9.25×10-3 moles of KCl with concentration 0.250 mol.dm-3 [3] 3) Find the concentrations of the following solutions in both mol.dm-3 and g.dm-3:- a) 0.400 moles of HCl in 2.00 dm3 of solution b) 12.5 moles of H2SO4 in 5.00 dm3 of solution c) 1.05g of NaOH in 500 cm3 of solution [6] 4) In a titration, 25.0 cm3 of a solution of sodium hydroxide required 18.80 cm3 of hydrochloric acid of concentration 0.0500 mol.dm-3 for neutralisation.