CHEM 120 Week 5 Exam 2 (Units 3 and 4)

1. A solution is prepared by dissolving 50 g of KCl (74.6 g/mol) to a volume of 1 L. What is the molarity of this solution? 2. You prepare a solution by dissolving 20 g of NaCl to a volume of 350 mL in water. What is the mass/volume % concentration of this solution? 3. When the following reaction goes in the forward direction, what is the base? 4. You are preparing a buffered solution. So far, your solution contains H2PO4- ions, what would you add to this solution to prepare your buffer system? 5. Select all examples where the Law of Conservation of Mass in not being followed. Select all that apply. 6. Balance the following chemical equation: FeBr3 + H2O → HBr + Fe2O3 (4 points). 7. What would be the products of the neutralization equation below. Select all that apply! 8. Calculate the Volume, in L, of 9.6 mole sample of oxygen gas at a pressure of 6.5 ATM at 16 °C. Show all work below. (5 points) 9. If you have 0.4 moles of C3H8 that you combust (balanced chemical reaction is: C3H8 + 3 O2 → 3 CO2 + 4 H2O), how many moles of CO2 will you generate? 10. I have 670 grams of O2. How many moles of O2 do I have? 11. You are looking at the results of a series of tests to determine if a series of solutions, A-E, would be considered acidic. Select ALL that you think are acidic based on the results below. 12. You have added HCl to water. What would you expect to occur? 13. If you increased the temperature of a sample of a gas, what would you expect would happen to the volume of the gas at a fixed pressure? 14. How many iron atoms are in Iron(III) chloride 15. In the chemical reaction 2 K(s) + 2 H2O(l) →2 KOH(aq) + H2(g) chose the statement that is true. 16. When 2.5 grams of sodium nitrate is dissolved in 60 ml of water in a beaker, the solute is the: 17. Consider vinegar and oil shaken together to form a mixture of with small droplets of oil dispersed in the vinegar. The best term for this would be: 18. A common chemical used in water treatment is Al2(SO4)3. What is the molecular mass of this compound? 19. In the equation: Al(s) + HCl(g) → AlCl3(s) + H2(g), select all reagents that would be considered gasses. Select all that apply. 20. Select all solutions that would be considered basic. 21. You have 2 L of a 10% NaCl solution. How many L of a 0.9% solution can you produce by diluting this solution? Show all of your work. (5 points total). 22. If a sample of gas with a volume of 20 ml at a pressure of 6 atm is moved to an area with a pressure of 2 ATM, what is the new volume of the gas? 23. For the following, consider a balloon filled with gas. Assuming ideal gas behavior, predict the effect: (4 points) 24. Balance the chemical equation below (4 points) SiF4 + H2O → SiO2 + HF 25. 20.0 grams of NaHCO3 decomposes following the balanced reaction below. How many grams of H2O will you form? Show all work.(6 points). 2 NaHCO3 → H2O + CO2 + Na2CO3 26. You dissolve a sample of MgF2 in water. The molarity of this solution is 1.4 M. What is the osmolarity of this solution? Show all work and units. Show all work. (5 points total) 27. If you dissolved 18 grams of NaBr (molecular mass 102.89 g/mol) in water to prepare 640 ml of solution, what is the Molarity of this solution? Show all work. (5 points) 28. Predict the products of this neutralization reaction. (4 points) HBr + NaOH ⟶