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CHEM 302 Name: ________________ Practice TEST 4: Solubility and Acids/Bases 1. A beaker of mysterious aqueous solution shows up on your desk one day. The pH of the aqueous solution is 3.74. Answer the following questions based on this information: a. What is the pOH of the substance? b. What is the [H+] of the substance? c. What is the [OH-] of the substance? d. If you tasted the solution, do you think it would taste bitter or sour? e. You have a total of 30ml of the substance. How many moles of H+ are present in the solution? 2. What is a ‘spectator ion’? 3. In lab you mix two aqueous solutions of ionic compounds. One solution contains sodium sulfide and the other contains iron (III) nitrate. After mixing the two solutions, a precipitate forms. Based on this information answer the following questions. Include state symbols (i.e. s, l, g, aq): a. Write the molecular equation (regular double displacement-type equation) for the reaction. Circle the precipitate. b. Write the gross ionic equation for this reaction. c. Which ions are spectator ions in the above equation (in ‘b’)? d. Write the net ionic equation for this reaction. 4. In order to perform the first part of an experiment you need 50ml of 0.15 M ammonium sulfate solution. In your stockroom you have dry ammonium sulfate powder. Explain how you would make the needed solution. 5. To finish the experiment you now need 75ml of 0.60 M of benzoic acid. Your stock solution is 3.5 M benzoic acid. What volume of the stock solution do you need in order to make the diluted solution? 6. 50.0ml of sodium hydroxide (NaOH) is neutralized with 155ml of 0.45M hydrochloric acid (HCl). a. What was the concentration of NaOH in the original 50.0ml? b. What is the final concentration (molarity) of NaOH (after neutralization)? c. What is the pH of the final solution (after addition of HCl)? 7. Give the molarity of each ion in the aqueous solutions below: a. 0.50M calcium nitrate b. 1.5M sodium sulfate c. 0.10M magnesium phosphate 8. What is the molarity of each substance below: a. 21.3mol of potassium chloride in 125L of water b. 12.0g sodium hydroxide in 200ml of water c. 58.4g of benzoic acid (C6H5COOH) in 1.50L of water 9. You are given an acid of unknown concentration. It is your task to determine the concentration of the acid. Explain how you would determine the concentration of H+ in the acid using methods/techniques learned in the lab.
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