Looking at the solubility curve above for KClO3, at 30 degrees Celsius how many grams will dissolve to make a saturated solution?
A. about 120 g (WRONG ANSWER)
B. 37 g
C. 10 g
D. 5 g
2. KCl is used to test the factors that affect the rate of dissolution.
Investigation 1 data:
Trial Number Temperature (oC) Stirring Dissolving Time (minutes)
1 20 no 30
2 40 no 20
3 60 no 10
How should the student design investigation 2 to finish testing the factors that affect the dissolving rate of KCl?
ANSWER: Keep the temperature at 20°C. Stir the solution.
3.How would you increase the conductivity of a solution?
A. Increase the temperature of the solution.
B. Use a weaker acid or base to make the solution.
C. Increase the concentration of ions in the solution.
D. Decrease the concentration of ions in the solution. (WRONG ANSWER)
4. Match what you know about the above solutions and their conductivity.
A solution like solution A that can conduct electricity ---- ELECTROLYTE
Solution B could have this dissolved in it------BOTH
Solution A could have this dissolved in it------ SALT, ACID, BASE
5. Sugar is added to tea to make sweet tea. In chemical terms, the sugar is the ___________ and the tea (mostly water) is the ____.
ANSWER: SOLUTE, SOLVENT
6. According to the pH chart, which is the strongest base?
ANSWER: NaOH
7.
Bleach
Hand Soap
Ammonia
What property do all three of these common household substances have in common?
When dissolved in water, they release hydrogen ions.
They all turn red litmus blue.
The react with metals to form hydrogen gas.(WRONG ANSWER)
They are all sour.
8. Match each to below to the area in which it belongs in the VENN diagram.
acid, base, or both
changes color in an indicator -- _____(Base is the wrong answer for this one)
Yields OH- ions in solution -- BASE(CORRECT)
pH is below 7---------------------ACID (CORRECT)
tastes sour------------------------ACID(CORRECT)
can conduct electricity in water- _____(Acid is the wrong answer for this one)
9. Use the information on the solubility graph to answer the question.
If 100 grams of the salt KBr are added to 100 g of water at 20oC, how would you describe the concentration of the solution?
ANSWER: SUPERSATURATED
10. What two products result from the neutralization reaction of an acid and a base?
For example: HCl + NaOH --> _____ + ______
ANSWER: SALT AND WATER
11. Jason is making lemonade and is getting impatient waiting for the sugar to dissolve. How can he speed up the rate of dissolution of the sugar?
A. Break up the sugar so the particle size is smaller.
B. Agitate the lemonade solution.
C. Add additional solute.
D. Increase the temperature of the lemonade. Then add ice to cool it back down so it doesn't taste bad.
Choose ALL correct answers.
CORRECT ANSWER: Increase the temperature of the lemonade. Then add ice to cool it back down so it doesn't taste bad.
12. How quickly will a mint dissolve?
Solute Time to dissolve (seconds)
mint cut in half, not swirled 140
mint cut in half, swirled 70
whole mint, not swirled 200
whole mint, swirled ?
mint cut into small pieces, not swirled 50
Students were asked to place a mint in their mouths and determine how long it took for the mint to dissolve. The condition of the mint varied in each student group.
One group of students were asked to leave a whole mint in their mouth, not moving it around, and let it dissolve. Another group swirled a whole mint around in their mouths, while the other groups used mints broken into smaller pieces. See the chart for all of the manipulated variables.
After reviewing that data table, what kind of result would you predict for the swirled, whole mint?
between 20 and 30 seconds
between 160 and 220 seconds
between 80 and 100 seconds
between 40 and 60 seconds(Incorrect answer)
HINT: Notice how the time changes when comparing the mint that has been cut in half. How does the time change when the students swirl that one around?
13. You are pulling your little sister along in a wagon. You exert 45 Newtons and are able to pull her 20 meters. How many joules of work did you do? Remember to consult your equation sheet for this one!
HINT: Did you find the work equation on your equation sheet? Work = force x distance? Take a look at the equation sheet and find it on there. Do you see how the F and d are next to each other? That means you will multiply the force and the distance.
