Page 281 - Chemistry eBook

Two very stable compounds, Freon-12 and Freon-14, are used as liquid refrigerants. A
Freon-12 molecule consists of one carbon atom, two chlorine atoms, and two fluorine atoms. A Freon-14 molecule consists of one carbon atom and four fluorine atoms.
81 In the space in your answer booklet, draw a structural formula for Freon-12. [1] 82 To which class of organic compounds do Freon-12 and Freon-14 belong? [1]
Sample Regents Questions
Base your answers to questions 83 through 85 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.
Ingredients:
Hard-Candy Lollipops Recipe
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.
83 Explain, in terms of the polarity of sugar molecules, why the sugar dissolves in water. [1]
84 Determine the concentration, expressed as percent by mass, of the sugar dissolved in the mixture produced in step 1. [1]
June 2013 #83
85 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. [1]
Answer
P.S./Chem.–June ’13 [15]
Answer: The polarity of sugar molecules is similar to the polarity of water
molecules.
Explanation: Like dissolves like. They’re both polar molecules.
UNIT 7: SOLUTIONS / SOLUBILITY © 280