Download std 6 review12ans

Name:______KEY_____________________
Date: ______________ Period: ______
Standard 6a: Students know the definitions of solute and solvent.
Match the following:
1. The chemical that is doing the dissolving (there is more of it) in the solution. b
a. Solute
2. The chemical that is being dissolved (there is less of it too) in the solution. a
b. Solvent
3. The ability of one chemical to dissolve into another. f
c. Miscible
4. An adjective used to describe 2 liquids that are able to dissolve into each other.c
d. Solution
5. A weak solution with very little solute in it – unsaturated.i
e. Homogenous
mixture
6. A strong solution with a lot of solute in it – saturated. j
7. A solution that has less solute that can be dissolved into it.h
f.
8. A solution that has as much solute dissolved in it as it can. g
g. Saturated
9. A homogenous mixture.d
h. Unsaturated
10. A combination in which all components are evenly distributed and has a uniform
i.
Dilute
j.
Concentrate
appearance. e
Solubility
2. Which of the substances in the table can act as either the solute or the solvent when mixed with 100 grams
of water at 20 °C?
3. A teaspoon of dry coffee crystals dissolves when mixed in a cup of hot water. This process produces a coffee
solution. The original crystals are classified as a
A solute.
B solvent.
C reactant.
D product.
Standard 6b: Students know how to describe the dissolving process at the molecular level by using the concept of
random molecular motion.
1. What are the steps that a solute must go through in order to be dissolved?
The solvent molecules attract and separate the solute molecules or ions (breaks down IMFs)
2. What is the universal solvent? water
3. What are the differences between a polar, a non-polar, and an ionic molecule?
Polar = covalent but + and – end
non-polar = covalent, but no charged ends
ionic = cation and anion
4. How can you predict if a solute will dissolve in a solvent?
Polar dissolve polar
nonpolar dissolves nonpolar
5. Will KBr dissolve in CH3F? Explain your answer.
Yes because KBr is ionic (polar) and CH3F is polar covalent
6. Will NaCl dissolve in CCl4? Explain your answer.
No because NaCl is ionic (polar) and CCl4 is nonpolar covalent
7. If the attractive forces among solid particles are less than the attractive forces between the solid and a
liquid, the solid will
A probably form a new precipitate as its crystal lattice is broken and re-formed.
B be unaffected because attractive forces within the crystal lattice are too strong for the dissolution to occur.
C begin the process of melting to form a liquid.
D dissolve as particles are pulled away from the crystal lattice by the liquid molecules.
8. Water is a polar solvent, while hexane is a nonpolar solvent. . Which of the examples illustrates a non-polar solute
in a polar solvent? (std 6b) B
Standard 6c: Students know temperature, pressure, and surface area affect the dissolving process.
1. How does each of the following affect the solubility?
a.
Increasing the surface area
d.
Stirring or shaking increases it
Increases it
b.
Increasing the pressure of a gas increases it
e.
Increasing the temp of a solid/liquid increases it
c.
Decreasing the surface area decreases it
f.
Increasing the temp of a gas decreases it
2. Use the solubility curve to answer the following questions.
Solubility Curve
240
220
Solubility (g solute/100g water)
200
180
160
140
120
100
80
60
40
20
0
0
10
20
30
40
50
60
70
80
90
100
Temperature (degrees C)
NaClO3
KBr
KNO3
NaCl
CO2
a. Which chemical has the greatest solubility at 80°C? NaClO3
b. How many grams of NaClO3 will dissolve in 100 g of water at 60 °C? about 150-155
c. How many grams of NaClO3 will dissolve in 400g of water at 20°C? 400g in 400g of water
d. Which molecule is a gas? How do you know? X or CO2 since curve goes down
e. How many more grams of KNO3 will dissolve if I raise the temperature from 40 to 80°C? 100g more
3. A technician prepared a solution by heating 100 milliliters of distilled water while adding KCl crystals until
no more KCl would dissolve. She then capped the clear solution and set it aside on the lab bench. After
several hours she noticed the solution had become cloudy and some solid had settled to the bottom of the
flask. Which statement best describes what happened?
A As the solution cooled, evaporation of water increased the KCl concentration beyond its solubility.
B Water molecules, trapped with the KCl crystals, were released after heating.
C At lower temperatures the solubility of the KCl decreased and recrystallization occurred.
D At increased temperatures the solubility of KCl increased and remained too high after cooling.
Standard 6d: Students know how to calculate the concentration of a solute in terms of grams per liter, molarity,
parts per million, and percent composition.
1. What are the formulas for each of the following?
a. % by volume:
c. Molarity
Liters of solute/liters of solution x 100%
Molarity = moles/liters
b. % by mass:
d. ppm
grams of solute/grams of solution x 100%
grams of solute/grams of solvent x 1 000 000
2. What is the molarity of a solution made with 45 g of KNO3 and 0.5L of water?
M = moles/L
1) covert grams of KNO3 into moles using molar mass then plug into formula
Final answer = 0.89 M
3. Children’s toothpaste has 0.7% fluorine by volume. If I purchase a 500 mL of toothpaste, how much of it is
fluoride? 0.7 = y / 500 x 100% solve for y final answer = 3.5 mL
4. Coca-cola contains 39 g of sugar in every 334g can. What is the percentage of sugar?
39/334 x 100% = 12%
5. By law, tap water needs to have between 0.7 and 1.3ppm of fluoride in it. If the sample Julia tested
contained 9 particles of fluorine out of every 10 million particles in solution, is the sample within legal
limits? Explain.
9/ 10,000,000 x 1 000 000 = 0.9 ppm
6. What is the density of a 45g sample of NaF in 2L of water? (density = g/L)
45/2 = 22.5 g/L
7. If the solubility of NaCl at 25 ºC is 36.2 g/100 g H2O, what mass of NaCl can be dissolved in 50.0 g of H2O?
A 18.1 g
B 36.2 g
C 72.4 g
D 86.2 g
8. How many moles of HNO3 are needed to prepare 5.0 liters of a 2.0 M solution of HNO3?
A 2.5
B5
C 10
D 20
9. The Dead Sea is the saltiest sea in the world. It contains 332 grams of salt per 1000 grams of water. What is
the concentration in parts per million (ppm)?
A 0.332 ppm
B 332 ppm
C 33,200 ppm
D 332,000 ppm