Chemistry Section _____ CHAPTERS 14 & 18 STUDY GUIDE Date: _________________________ Name: _____________________________ A. Multiple Choice. (20 points) 1. An aqueous solution of copper(II) sulfate is poured through a filter paper cone. What passes through the paper? (1) only the solvent (3) both solute and solvent (2) only the solute (4) neither solute nor solvent 2. Nonpolar solvents will most easily dissolve solids that are (1) ionic (2) covalent (3) metallic 3. Which substance is insoluble? (1) calcium chloride (2) ammonium phosphate (4) colored (3) barium sulfate (4) potassium chromate 4. Which amount of compound dissolved in 100 g of water at the stated temperature represents a saturated solution (3) 40 g KCl at 60°C (1) 20 g KClO3 at 80°C (4) 60 g NaNO3 at 40°C (2) 40 g KNO3 at 25°C 5. What is the molarity of a 1.00 L solution containing 116 g KF? (1) 1.00 M (2) 2.00 M (3) 3.00 M (4) 4.00 M 6. If 100 mL of a 1.0 M solution evaporates to a volume of 25 mL, what is the concentration of the resulting solution? (1) 0.25 M (2) 0.50 M (3) 2.0 M (4) 4.0 M 7. What is the vapor pressure of water at 105°C? (1) 100 kPa (2) 101.3 kPa (3) 110 kPa (4) 120 kPa 8. According to the Arrhenius theory, citric acid in oranges and acetic acid in vinegar are classified as acids because their aqueous solutions contain (1) hydrogen ions (2) hydrogen atoms (3) hydroxide ions (4) hydroxide atoms 9. How many milliliters of 2.5 M HCl are required to exactly neutralize 15 mL of 5.0 M NaOH? (3) 15 mL (4) 30 mL (1) 2.5 mL (2) 7.5 mL 10. Which pH value represents the solution with the lowest OH– concentration? (1) 1 (2) 7.0 (3) 10 (4) 14 Created 1 April 2014 B. Short Answer. (30 points) Base your answers to questions 11 through 13 on the information below. Some carbonated beverages are made by forcing carbon dioxide gas into a beverage solution. When a bottle of one kind of carbonated beverage is first opened, the beverage has a pH of 3. 11. State, in terms of the pH scale, why this beverage is classified as acidic. [3] Anything with a pH less than 7 is considered acidic 12. Using Table M, identify one indicator that is yellow in a solution that has the same pH value as this beverage. [3] bromothymol blue or bromocresol green or thymol blue (any with yellow at low pH) 13. After the beverage bottle is left open for several hours, the hydronium ion concentration in the beverage decreases to of the original concentration. Determine the new pH of the beverage solution. [3] 10–3 / 1000 = 10–6, therefore pH = 6 Base your answers to questions 14 and 15 on the information below and on your knowledge of chemistry. In a titration, 50.0 milliliters of 0.026 M HCl (aq) is neutralized by 38.5 milliliters of KOH (aq). 14. In the space below, show a numerical setup for calculating the molarity of the KOH (aq). [3] MAVA = MBVB therefore MB = MAVA / VB = (0.026 M x 50.0 mL) / 38.5 mL 15. Complete the neutralization equation below by writing the formula of the missing product. [3] KOH (aq) + HCl (aq) → KCl (aq) + H2O (l) Go on to the next page. Base your answers to questions 16 through 18 on the information below and on your knowledge of chemistry. Chemical concepts are applied in candy making. A recipe for making lollipops is shown below. Hard‐Candy Lollipops Recipe Ingredients: 414 grams of sugar 177 grams of water 158 milliliters of light corn syrup Step 1: In a saucepan, mix the sugar and water. Heat this mixture, while stirring, until all of the sugar dissolves. Step 2: Add the corn syrup and heat the mixture until it boils. Step 3: Continue boiling the mixture until the temperature reaches 143°C at standard pressure. Step 4: Remove the pan from the heat and allow it to stand until the bubbling stops. Pour the mixture into lollipop molds that have been coated with cooking oil spray. 16. Explain, in terms of the polarity of sugar molecules, why the sugar dissolves in water. [3] Both sugar and water are polar molecules and opposite charges attract 17. Determine the concentration, expressed as percent by mass, of the sugar dissolved in the mixture produced in step 1. [3] %mass = ( mass solute / mass solution ) x 100% = ( 414 g / 591 g ) x 100% = 70.1% 18. Explain, in terms of the concentration of sugar molecules, why the boiling point of the mixture in step 3 increases as water evaporates from the mixture. [3] As water evaporates, the concentration of sugar increases which increases Tb __________
Go on to the next page. Base your answers to questions 19 through 20 on the information below. In a titration, a few drops of an indicator are added to a flask containing 35.0 milliliters of HNO3 (aq) of unknown concentration. After 30.0 milliliters of 0.15 M NaOH (aq) solution is slowly added to the flask, the indicator changes color, showing the acid is neutralized. 19. The volume of the NaOH(aq) solution is expressed to what number of significant figures? [3] 30.0 mL has three significant digits. 20. In the space below, show a numerical setup for calculating the concentration of the HNO3 (aq) solution. [3] MAVA = MBVB therefore MA = MBVB / VA = (0.15 M x 30.0 mL) / 35 mL This is the last page.