CHEM 120 Week 3 Quiz

1. Question:A reaction that releases energy as it is classified as an ____while a reaction that absorbs energy as it occurs is classified as an ____. 2. Question:Which coefficient is placed in front of potassium to balance the following equation?K H2SO4-K2SO4 H2= ____ 3. Question:Which coefficient is placed in front of HCI to balance the following equation?Ca(OH)2 ? HCICaCl2 H2O = ____ 4. Question:Sodium reacts with oxygen to form sodium oxide and has the following chemical equation: 4 Na O2 Na2O. How many mole(s) of oxygen gas (O2) are needed to react with 8.0 moles of Na? 2.0 5. Question:Magneisum reacts with oxygen to form magnesium oxide and has the balanced chemical equation: 2Mg O2  2 MgO. How many moles of MgO are produced when 5 moles O2 reacts completely? 6. Question: Determine number of atoms of the following molecule Na2CO3. Using periodic table determine themolar mass for this molecule: Na=2 C=1 O=3 Molar Mass (Na) 2*23=46 (C) 1*12=12 (O)3*16=48 7. Question: Determine number of atoms of the following molecule BaSO4. Using periodic table determine the molarmass for this molecule: B=1 S=1 O=4 Molar Mass (B) 1*137=137 (S) 1*32=32 (O) 4*16=64 8. Question: Calculate the concentration of NaCl (in water) solution in several ways and are given the following info:25g NaCl, 500mL solution. Molecular weight of NaCl= 58.44 calculate mass/volume percent concentrationand molarity of the solution 9. Question: What volume (L) of a 1.5 M KOH solution can be prepared by diluting0.2 L of a 5M KOH solution? CV1= C2V2 C1=5 V1=0.2 C2=1.5 V2=? 10. Question: What is the molecular mass of N2O