Practice Test for 6.1-6.3 1. Complete the following molarity calculations: a. What is the molarity of a solution containing 25.3 grams of copper (II) chloride dissolved in 140 mL of water? b. How many grams of sodium hydroxide are needed to make 2 L of a 0.05 M solution?
6.02 x 1023 atoms C. 6.02 x 1023 ions B. 6.02 x 1023 grams D. 6.02 x 1023 molecules 5. What ts the correct unit of a formula weight? A. gram B mol C. gram/mol D. mole/gram 6. How many individual atoms are there in 250 grams of O2?
(c) Calculate the mass of water formed when 20 g of methane undergoes complete combustion. 6 Deduce the empirical formulae of the following: Moles and empirical formulae 1 Calculate the molar mass of these compounds. (Relative atomic masses H = 1; N = 14; O = 16; Mg = 24; S = 32; Ca = 40; K =39; Cr = 52; Fe = 56.) (a) calcium ethanoate, Ca(CH3CO2)2 (b) chromium sulfate Cr2(SO4)3 (c) magnesium hydroxide, Mg(OH)2 (d) potassium cyanoferrate(III), K3Fe(CN)6 2 When 2.4 g of magnesium
• 5.01 x 1022 C atoms • 2.76 x 1023 C atoms • 3.31 x 1024 C atoms • 5.50 x 1023 C atoms How many Cl atoms are in 0.0728 g of PCl3? • 1.32 x 1023 Cl atoms • 3.19 x 1020 Cl atoms • 1.81 x 1024 Cl atoms • 9.58 x 1020 Cl atoms Calculate the molar mass of (NH4)2SO4 • 114.11 g/mol • 228.22 g/mol • 132.15 g/mol • 118.14 g/mol 2. Calculate the mass of 4.50 moles of Ca3PO4 • 215 g • 968 g • 87.1 g • 392 g 3. The mineral pyrolusite is a compound of 55Mn and 16O. If 63% of the mass of pyrolusite is due to manganese, what is the empirical formula of pyrolusite?
Verify that the atomic mass of magnesium is 24.31 amu, given the following information: [pic], mass = 23.985042 amu; percent abundance = 78.99% [pic], mass = 24.985837 amu; percent abundance = 10.00% [pic], mass = 25.982593 amu; percent abundance = 11.01% 4. Naturally occurring neon is a mixture of three isotopes with the following masses and abundances: Mass Number Atomic Mass % Abundance 20
Practice Question for Exam 2 Chem 103 |A chemical reaction requires 30.77 kJ. How many kilocalories does this correspond to? | |A) 7,354 kcal B) 7.354 kcal C) 128.7 kcal D) 0.1287 kcal E) 30.77 kcal | |776 J is the same quantity of energy as | |A) 7.76 × 105 kJ. B) 1.85 × 102 kcal. C) 0.185 kcal.
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.
Review Questions for the Free Response Section of the Semester Two (Final) Examination Name:_________________________________ Date: _____________ 1. Calculate the number of moles of sulfur dioxide (SO2) in 76.1 g SO2. S = 32 grams/mole O = 12 grams/mole 2. Determine the percentage composition of magnesium carbonate (MgCO3). Mg = 24 g/mole Percent of an element = Mass of the element X 100 C = 12 g/mol Total formula mass O = 16 g/mol 3.
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. Find the concentration of the sodium hydroxide in both mol.dm-3 and g.dm-3. [3] NaOH + HCl ( NaCl + H2O 5) Calculate the volume of 0.05 mol.dm-3 potassium hydroxide solution that is required to react exactly with 25.0 cm3 of 0.0150 mol.dm-3 nitric acid. [2] HNO3 + KOH ( KNO3 + H2O 6) In a titration, 20.0 cm3 of barium hydroxide solution required 28.60 cm3 of sulfuric acid of concentration 0.0250 mol.dm-3 for neutralisation. Find the concentration of the barium hydroxide in both mol.dm-3 and g.dm-3.
3. What is the relationship between a photon and a quantum leap? • When a quantum leap occurs, a single photon is emitted. 4. Using the periodic table, determine the result of the following calculation: the number of electrons in the outer shell of a hydrogen atom minus the number of electrons in the outer shell of a helium atom plus the number of electrons in the outer shell of a hydrogen atom.