Nurs 480: Quiz 3, chem 120(with answers)

1. Question : (TCO 5) In the following reaction, HCl is ; and NaCl is . NaOH + HCl à NaCl + H2O Student Answer: Catalyst; reactant Product; reactant reactant; catalyst reactant; product Points Received: 3 of 3 Comments: Question 2.Question : (TCO 5) Which coefficient is placed in front of H2O to balance the following equation? Ca(OH)2 + HCl --- CaCl2 + ? H2O Student Answer: 1 2 3 4 5 Points Received: 3 of 3 Comments: Question 3.Question : (TCO 5) Which coefficient is placed in front of CaO to balance the following equation? CaCO3 à ? CaO + CO2 Student Answer: 1 2 3 4 5 Points Received: 3 of 3 Comments: Question 4.Question : (TCO 5) Sodium reacts with oxygen to form sodium oxide and has the following balanced chemical equation: 4 Na + O2 -- 2 Na2O. How many mole(s) of oxygen gas (O2) are needed to react with 2.0 moles of Na? Student Answer: 0.5 moles 3.0 moles 1.0 moles 2.0 mole 4.0 moles Points Received: 0 of 3 Comments: Question 5.Question : (TCO 5) Magnesium reacts with oxygen to form magnesium oxide and has the following balanced chemical equation: 2 Mg + O2 -- 2 MgO. How many mole(s) of MgO are produced when 4 mole O2 reacts completely? Student Answer: 2 mole 4 mole 10 mole 8 mole 1 mole Points Received: 3 of 3 Comments: Question 6.Question : (TCO 5) (a) Determine the number of atoms for each element present in the following molecule: Cu(CN)2 (2 points). (b) Using the periodic table of elements, determine the molar mass for this molecule (3 points). Show your work. Student Answer: Cu-1 C-2 N-2 C= 12.01 x2 (24.02), Cu= 63.55, N= 14.01 x2 (28.02) Molar Mass= 115.59 Instructor Explanation: Correct Answer: See Chapter 5. (a) Number of atoms: 1 Cu, 2 N, 2 C (b) Atomic mass: Cu = 63.546, N = 14.007, C = 12.01 Molar mass = (1 × 63.546) + (2 × 14.007) + ( 2 × 12.01) = 115.6 g per mole Points Received: 5 of 5 Comments: Question 7.Question : (TCO 5) (a) Determine the number of atoms for each element present in the following molecule: Mg(NO3)2 (2 points). (b) Using the periodic table of elements, determine the molar mass for this molecule (3 points). Show your work.