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Honors Unit 8: Solutions Class Packet

Key Ideas

Matter is classified as a pure substance or as a mixture of substances. (3.1q) Mixtures are composed of two or more different substances that can be separated by physical means. When

different substances are mixed together, a homogeneous or heterogeneous mixture is formed.(3.1s) The proportions of components in a mixture can be varied. Each component in a mixture retains its original

properties. (3.1t) The three phases of matter (solids, liquids, and gases)have different properties.(3.1kk) Differences in properties such as density, particle size, molecular polarity, boiling point and freezing point,

and solubility permit physical separation of the components of the mixture. (3.1nn) A solution is a homogeneous mixture of a solute dissolved in a solvent. The solubility of a solute in a given

amount of solvent is dependent on the temperature, the pressure, and the chemical natures of the solute and solvent. (3.1oo)

The concentration of a solution may be expressed as molarity (M), percent by volume, percent by mass, or parts per million (ppm). (3.1pp)

The addition of a nonvolatile solute to a solvent causes the boiling point of the solvent to increase and the freezing point of the solvent to decrease. The greater the concentration of particles, the greater the effect. (3.1qq)

Solutions Review1


1. Draw the following descriptions:

Pure element Pure compound Mixture of Mixture of Mixture oftwo elements an element & two diatomic

a compound elements &a compound

2. Classify each of the following with the combination of terms listed below.

pure substance – element mixture – homogeneouspure substance – compound mixture – heterogeneous

a. HCl (aq) d. sugar (C11H22O11) g. KBr (s) j. Soilb. Cl2 (g) e. water h. CH2(OH)2 (aq) k. Sodiumc. Hg (l) f. iron oxide i. NH3 (l) l. salt water

3. Matter that is composed of two or more different elements chemically combined in a fixed proportion is classified as (1) a compound (2) an element (3) a mixture (4) a solution

4. A compound differs from an element in that a compound(1) is homogeneous (3) can be decomposed by a chemical reaction(2) has a definite composition (4) has a definite melting point

5. A compound differs from a mixture in that a compound always has a(1) homogeneous composition (3) minimum of three elements(2) maximum of two elements (4) heterogeneous composition

6. A heterogeneous material may be(1) an element (2) a compound (3) a pure substance (4) a mixture

7. Which statement is an identifying characteristic of a mixture?(1) a mixture can consist of a single element(2) a mixture can be separated by physical means(3) a mixture must have a definite composition by weight(4) a mixture must be homogeneous

8. Which must be a mixture of substances? (1) solid (2) liquid (3) gas (4) solution

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9. Which substance can be decomposed by chemical means? (1) aluminum (2) octane (3) silicon

10. Two substances, A and Z, are to be identified. Substance A cannot be broken down by a chemical change. Substance Z can be broken down by a chemical change. What can be concluded about these substances?

(1) Both substances are elements.(2) Both substances are compounds.(3) Substance A is an element and substance Z is a compound.(4) Substance A is a compound and substance Z is an element.

11. Which terms are used to identify pure substances?(1) an element and a mixture (3) a solution and a mixture(2) an element and a compound (4) a solution and a compound

12. Two different samples decompose when heated. Only one of the samples is soluble in water. Based on this information, these two samples are

(1) both the same element (3) both the same compound(2) two different elements (4) two different compounds

13. Tetrachloromethane, CCl4, is classified as a(1) compound because the atoms of the elements are combined in a fixed proportion(2) compound because the atoms of the elements are combined in a proportion that varies(3) mixture because the atoms of the elements are combined in a fixed proportion(4) mixture because the atoms of the elements are combined in a proportion that varies

14. Fill in the tables below. Solution Formula Solute Name Solvent

Formula Solution Name Solute Formula

MgBr2(aq) aqueous potassium nitrate

K2SO4(aq) aqueous sodium acetate

FeCl3(aq) aqueous ammonium hydroxide

CuSO4(aq) aqueous lithium bromide

Ba(NO3)2 (aq) aqueous magnesium hypochlorite

(NH4)2CO3(aq) aqueous iron (II) nitrate

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Vapor Pressure

Liquids evaporate when they are left in the open air. This is also known as ____________________. Liquids

also go through this phase changed in closed containers. The vapor that is produced in either container exerts

a pressure on top of the liquid phase. This pressure is known as _________________ ____________________.

In order for the vapor to escape its original liquid phase completely its pressure must overcome the regular

atmospheric pressure above it. As temperature of the liquid increases, the number of particles evaporating

____________________ and the vapor pressure ____________________. Therefore, temperature and vapor

pressure have a direct correlation.

Under high atmospheric pressure, the liquid will have a harder time escaping the liquid phase so the

temperature at which it boils is higher than normal. Under low atmospheric pressure, the liquid will have an

easier time escaping the liquid phase so the temperature at which it boils is_________________ than normal.

Use Table H to answer these questions:

1. Which substance has the lowest boiling point? ____________________

2. Which substance has a normal boiling point of 100C? ____________________

3. What is the normal boiling point of propanone? ____________________

4. Which substance has the highest vapor pressure at 40C? ____________________

5. At what pressure will water boil at 90C? ____________________

6. At what pressure will propanone boil at 20C? ____________________

7. What temperature will ethanoic acid boil at 48kPa? ____________________

8. What temperature will water boil at 110kPa? ____________________

9. Which substance has the greatest IMF? ____________________

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Solubility Table F

Use Table F to determine if the following compounds are soluble or insoluble.

a. NaCl e. K3PO4 i. calcium hydroxide

b. PbBr2 f. MgCO3 j. copper (II) hydroxide

c. CaSO4 g. NH4NO3 k. lead(II) sulfate

d. potassium chromate h. sodium hydrogen carbonate

l. ammonium sulfide

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Key:I – InsolubleS – Soluble

Ace

tate

Bro

mid

e

Car

bona

te

Chl

orat

e

Chl

orid

e

Chr

omat

e

Hyd

roxi

de

Hyd

roge

n C

arbo

nate

Iodi

de

Nitr

ate

Perc

hlor

ate

Phos

phat

e

Sulfa

te

Sulfi

de

AluminumAmmoniumBariumCalciumDimercuryCopper IIIron IIIron IIILithiumLeadMagnesiumPotassiumSilverSodiumStrontiumZinc


Double Replacement and Solubility

1. Double replacement reactions require the cations to switch with the anions. Identify which of the following DR reactions are written correctly. Correct the mistakes in the wrong reactions:

a. (NH4)3PO4(aq) + AlCl3(aq) Al(PO4)3(s) + NH4Cl3(aq) ____________________________________

b. NaCl(aq) + AgNO3(aq) AgCl(S) + NaNO3(aq) ____________________________________

c. NaBr(aq) + PbI2(aq) NaI(aq) ____________________________________________________

d. K2SO4(aq) + BaI2(aq) BaSO4(s) + 2KI(aq) ____________________________________

e. CaCl2(aq) + Li2CO3(aq) 2LiCl(s) + CaCO3(aq) ____________________________________

2. Write the balanced chemical equation for each of the following descriptions. Use Table F to determine the state of the reactants and products – (s) or (aq). Write “soluble” or “insoluble” under each reactant and product. Square off the precipitate.

(a) Solutions of sodium carbonate and silver nitrate are mixed to form sodium nitrate and silver carbonate.

(b)AgC2H3O2 (aq) is mixed with NaCl (aq) to form AgCl and NaC2H3O2.

(c) Solutions of potassium sulfate and calcium chlorate are mixed to form potassium chlorate and calcium sulfate.

(d)CaCl2 (aq) and Na2S (aq) are mixed to form CaS and NaCl.

(e)What do all the above double replacement reactions have in common

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Solubility Table G

Check the conditions under which each of the following solutes will be most soluble.

Solute Name Solute Formula

Temperature Pressure Best Solvent

Low High Low High No Effect

H2O CCl4

potassium nitrate KNO3(s)

hydrogen chloride HCl(g)

nitrogen trihydride NH3(g)

ammonium chloride NH4Cl(s)

carbon dioxide CO2(g)

potassium iodide KI(s)

potassium chlorate KClO3(s)

Naphthalene, a nonpolar substance that sublimes at room temperature, can be used to protect wool clothing from being eaten by moths.

a. Explain, in terms of intermolecular forces, why naphthalene sublimes.

b. Explain why naphthalene is not expected to dissolve in water.

c. The empirical formula for naphthalene is C5H4 and the molecular mass of naphthalene is 128 grams/mole. What is the molecular formula for naphthalene?

State whether each of the following solutions is saturated, unsaturated, or supersaturated.

(a) 80 g NaNO3 in 100 g H2O at 10ºC ___________________________

(b) 75 g NaNO3 in 100 g H2O at 10ºC ___________________________

(c) 90 g NaNO3 in 100 g H2O at 10ºC ___________________________

(d) 90 g KNO3 in 100 g H2O at 50ºC ___________________________

(e) 90 g KI in 100 g H2O at 50ºC ___________________________

(f) 5 g KClO3 in 100 g H2O at 5ºC ___________________________

(g) 40 g KCl in 50 g H2O at 60ºC ___________________________

(h) 35 g NaNO3 in 50 g H2O at 10ºC ___________________________7


(i) 5 g KClO3 in 50 g H2O at 5ºC ___________________________

(j) 5 g KClO3 in 200 g H2O at 5ºC ___________________________

(k) 30 g NH4Cl in 200 g H2O at 10ºC ___________________________

(l) 40 g SO2 in 200 g H2O at 5ºC ___________________________

Tell how many MORE grams of each solute must be added to 100 g of water to form a saturated solution at that temperature.

Grams Solute per

100 g H2O

Solute Added to

make Saturated

Grams Solute per

100 g H2O

Solute Added to

make Saturated

Grams Solute per

200 g H2O

Solute Added to

make Saturated

a. 35 g KNO3 at 40ºC

e. 35 g NaCl at 90ºC

i. 25 g NH3 at 5ºC

b. 50 g NH3 at 10ºC

f. 5 g NH3 at 90ºC

j. 30 g NaNO3

at 50ºCc. 15 g KCl at

75ºCg. 10 g KClO3

at 40ºCk. 15 g KClO3

at 75ºCd. 95 g KI at

15ºCh. 17 g KCl at

60ºCl. 5 g KCl at

75ºC

Tell how many grams of each solute will crystallize/precipitate/settle. Assume all solutions are saturated and in 100 grams of H2O.

Amount cooled Amount Precipitated

Amount cooled Amount Precipitated

a. KNO3 (aq) is cooled from 70ºC to 40ºC

e. NaCl (aq) is cooled from 100ºC to 40ºC

b. NH4Cl (aq) is cooled from 90ºC to 20ºC

f. KNO3 (aq) is cooled from 65ºC to 25ºC

c. KCl (aq) is cooled from 55ºC to 30ºC

g. KClO3 (aq) is cooled from 100ºC to 40ºC

d. KI (aq) is cooled from 20ºC to 5ºC

h. NaNO3 (aq) is cooled from 45ºC to 10ºC

Rank the following solids in order from least to most soluble in 100 g H2O at 50ºC : NH4Cl, NaNO3, KClO3, KNO3

Rank the following gases in order from least to most soluble in 100 g H2O at 50ºC : NH3, SO2, HCl

Molarity

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1. Calculate the molarity of each of the following solutions:

(a) 2.5 mol of NaOH in 0.500 L of solution (b) 1.8L of solution containing 3.3 mol KNO3

(c) 30. g of NaOH in 0.500 L of solution (d) 522 g of K2SO4 in 1.5 L of solution

(e) 12 g of HCl in 250 mL of solution

2. Calculate the total moles of solute in each of the following solutions:

(a) 1.7 L of 0.35M NaOH (b) 50 mL of 3.3-molar KNO3

(c) 5.0 L of 1.25 M NaOH (d) 116 mL of 1.5 M K2SO4

3. Calculate the total grams of solute in each of the following solutions:

(a) 1.0 L of 0.5 M CaCl2 (b) 500 mL of 3.3-molar KNO3

(c) 0.25 L of 1.0 M NaOH (d) 42 mL of 1.7 M K2SO4

4. Find the Molarity of the following solutions:

a.) 0.50 moles of sodium chloride in 0.50 liters.

b.) 2.00 moles of ammonia in 0.50L solution.

c.) 0.50 moles of sucrose dissolved in 2.00L.

d.) 80.0 grams of NaOH in one liter of solution.

e.) 101 grams of KNO3 in 500. ml of solution.

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f.) 202.5 grams of CuCl2 dissolved in 2L of water.

g.) 74 grams of Ca(OH)2 in 500. mL of water.

5. Find the mass needed for each solution:

a.) A solution of 1.00L of 2.00M NaCl

b.) A solution of 0.500L of 3.00M NaOH

c.) A solution of 6.00L of 0.50M CaCl2

d.) A solution of 4.00L of 0.25M CuSO4.5H2O

e.) A solution of 3.00L of 1.50M NaF

f.) A solution of 1.50L of 1.50M Mg(NO3)2

g.) A solution of 4.50L of 6.00M HCl

h.) A solution of 5.00L of 2.50M H2SO4

Percent By Mass

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Calculate the percent by mass of the following solutions:

1. 50.0 grams of solute in 200.0 grams of solution

2. 25.0 grams of solute in 150.0 grams of solution

3. 15.0 grams of NaCl in 250.0 grams of solution

4. 10.0 grams of KI in 1000.0 grams of solution

5. 2.0 grams of solute in 2000.0 grams of water

6. 0.500 grams of solute in 150.0 grams of water

7. 0.250 grams of NaBr in 125.0 grams of water

8. 0.0125 grams of O2 in 25,000,000.0 grams of water

9. What could be a better unit to express your answer to number 8?

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Parts Per Million

1. Calculate the concentration of chlorine in ppm in a swimming pool if there is 0.02 g of chlorine in 10,000 g of pool water.

2. Exposure to lead has been linked to delays in physical and mental development and attention deficit

disorders in children as well as kidney problems in adults. One source of this toxic heavy metal is drinking water in older homes whose plumbing contains lead. Water with a lead concentration of below 0.015ppm is considered safe to drink. A 100 g water sample taken from a home contains 1.2 x 10-6 grams of lead. Is this water considered safe to drink?

3. The health of fish depends on the amount of oxygen dissolved in the water. A dissolved oxygen (DO) concentration between 6 parts per million and 8 parts per million is best for fish health. A DO concentration greater than 1 part per million is necessary for fish survival. Fish health is also affected by water temperature and concentrations of dissolved ammonia, hydrogen sulfide, chloride compounds, and nitrate compounds. A student’s fish tank contains fish, green plants, and 3800 grams of fish-tank water with 2.7 x 10-2 gram of dissolved oxygen.

a.) State how an increase in the temperature of the fish-tank water affects the solubility of oxygen in the water.

b.) Determine if the DO concentration in the fish tank is healthy for fish. Your response must include:• a correct numerical setup to calculate the DO concentration in the water in parts per million • the calculated result • a statement using your calculated result that tells why the DO concentration in the water is or is not healthy for fish

c.) Explain, in terms of molecular polarity, why oxygen gas has low solubility in water. Your response must include both oxygen and water.

d.) Under what kind of conditions of temperature and pressure would oxygen gas be most soluble in water?

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e.) An aqueous solution has a concentration of 7 ppm of oxygen dissolved in 1000. grams of water. Calculate the amount of oxygen in the solution in grams. Your response must include both a correct numerical setup and the calculated result.

4. A safe level of fluoride ions is added to many public drinking water supplies. Fluoride ions have been found to help prevent tooth decay. Another common source of fluoride ions is toothpaste. One of the fluoride compounds used in toothpaste is tin(II) fluoride. A town located downstream from a chemical plant was concerned about fluoride ions from the plant leaking into its drinking water. According to the Environmental Protection Agency, the fluoride ion concentration in drinking water cannot exceed 4 ppm. The town hired a chemist to analyze its water. The chemist determined that a 175-gram sample of the town’s water contains 0.000 250 gram of fluoride ions.

a. Draw a Lewis electron-dot diagram for a fluoride ion.

b. What is the chemical formula for tin(II) fluoride?

c. How many parts per million of fluoride ions are present in the analyzed sample?

d. Is the town’s drinking water safe to drink? Support your decision using information in the passage and your calculated fluoride level in question c.

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Colligative Properties

1. Which solution has the highest boiling point?(1) 0.5 M NaCl(2) 0.5 M CaCl2

(3) 1.0 M (NH4)3PO4

(4) 2.0 M CH3OH

2. Compared to pure water, an aqueous solution of calcium chloride has a (1) higher boiling point and higher freezing point (2) higher boiling point and lower freezing point(3) lower boiling point and higher freezing point(4) lower boiling point and lower freezing point

3. Which solution has the highest boiling point?(1) 1.0 M KNO3 (3) 1.0 M Ca(NO3)2

(2) 2.0 M KNO3 (4) 2.0 M Ca(NO3)2

4. Which solution has the lowest freezing point?(1) 10. g of KI dissolved in 100. g of water(2) 30. g of KI dissolved in 100. g of water(3) 20. g of KI dissolved in 200. g of water(4) 40. g of KI dissolved in 200. g of water

5. As water is added to a 0.10 M NaCl aqueous solution, the conductivity of the resulting solution(1) decreases because the concentration of ions decreases(2) decreases, but the concentration of ions remains the same(3) increases because the concentration of ions decreases(4) increases, but the concentration of ions remains the same

6. Which aqueous solution of KI freezes at the lowest temperature?(1) 1 mol of KI in 500. g of water (3) 1 mol of KI in 1000. g of water(2) 2 mol of KI in 500. g of water (4) 2 mol of KI in 1000. g of water

7. Compared to a 2.0 M aqueous solution of NaCl at 1 atmosphere, a 3.0 M aqueous solution of NaCl at 1 atmosphere has a

(1) lower boiling point and a higher freezing point(2) lower boiling point and a lower freezing point(3) higher boiling point and a higher freezing point(4) higher boiling point and a lower freezing point

8. Based on Reference Table F, which of these saturated solutions has the lowest concentration of dissolved ions?(1) NaCl(aq) (2) MgCl2(aq) (3) NiCl2(aq) (4) AgCl(aq)

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Solutions VocabularyDIRECTIONS: On the line rewrite the question substituting one of the vocabulary words for the underlined

words. Then circle the correct answer or answer on the second line.

Ex: Which substance undergoes a phase change from the liquid to the gas state at 100C? vaporization

(1) CO2 (2) H2 (3) H2O (4) O2

WORD BANK

saturated solution solution dilute solubleunsaturated solution solute concentrated insolublesupersaturated solution solvent equilibrium miscibledistillation solubility dissociation immiscible

1. Which is a homogeneous mixture?(1) salt (2) concrete (3) bronze (4) granite

2. What is the dissolved substance in NH4Cl(aq)? ______________________________

3. A state of balance between dissolved and undissolved solute exists in which type of solution?(1) saturated (2) unsaturated (3) supersaturated

4. Which substance does not dissolve in water? (Hint: use Table F)(1) Ca(NO3) 2 (2) CaCrO4 (3) Ca(OH)2 (4) CaCO3

5. Which substance dissolves easily in water? (Hint: use Table F)(1) KCl (2) AgCl (3) PbCl2 (4) Hg2Cl2

6. As temperature increases, the number of grams dissolved in a given quantity of solvent of which substance increases?

(1) HCl (2) KClO3 (3) NH3 (4) SO2

7. Which pair are liquids that mix to form a solution?(1) hexane and water (2) CCl4 and water (3) ethanol and water

8. Which is a solution that contains more solute than will normally dissolve at 70C?(1) 10g SO2 in 100 g of water (3) 30g KClO3 in 100 g water(2) 10g NH3 in 100 g of water (4) 30g NaCl in 100 g water

9 Which is a solution that contains less solute than will normally dissolve at 50C?(1) 84g SO2 in 100g of water (3) 84g KNO3 in 100g water(2) 84g NH4Cl in 100g of water (4) 84g NaNO3 in 100g water

10. At 25C, which is a solution that contains relatively little dissolved solute ? (1) a saturated solution of NaNO3(aq) (2) a saturated solution of KClO3

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Unit 8 Solutions Review

Vapor Pressure Table HAs the temperature of a liquid increases more gas particle evaporate and create a higher vapor pressure. Boiling point is directly affected by changes in pressure.

a. What is the normal boiling point of water? ____________________ ethanoic acid? _____________

b. Which liquid has the highest boiling point at 50kPa? ________________

c. Which liquid has the weakest forces? ________________

d. What is the boiling point of propanone at 85kPa? ________________

e. What is the pressure at which water boils at 110C? ________________

Solubility Table FSolubility depends on the nature of the solution, temperature, and pressure.

a. Explain why Styrofoam dissolves in acetone but not water in terms of polarity.

b. Using Table F determine if the following are soluble or insoluble:

1) NaNO3 _____ 3) Magnesium hydroxide _____

2) Ammonium carbonate _____ 4) CaCO3 _____

c. Increases in temperature make solids dissolve _________ but gases dissolve ______________.

d. Give examples from Table G to support your previous answer.

e. Pressure only affects the gas phase. Increases in pressure _______________ the solubility of a gas.

Solubility Curves Table GVery soluble solutes are found near the top of table G. Those are also more concentrated. Points that fall above a line for a solute are called supersaturated. Points below are called unsaturated. Points on the line show saturated solutions. Watch out for the amount of solvent in the question!!!

a. What salt is the most concentrated at 10C? ________________ Which gas? __________________

b. How much KNO3 dissolves at 70C in 100 grams of water? ___________

c. At what temperature will 20g of SO2 dissolve in 100g of water? ___________

d. At what temperature will 40 grams of KNO3 dissolve in 200g of water? ___________

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e. How many grams of NaCl will dissolve in 50 grams of water at 100C? ___________

f. How many grams of KCl will precipitate out of 100 gram of water if the solution is cooled from 80C to

20C?

g. What type of solution is created when 50 grams of NaNO3 are dissolved in 50 grams of water at 20C?

Concentration Table TMolarity is expressed as the moles of solute per liter of solution. It is the most common unit of concentration. Percent by mass and part per million formulas are both on Table T and both require the amount of SOLUTION on the denominator. NOT water or solvent!

a. What is the molarity of 5.0 moles of NaCl in 400mL of water?

b. What is the volume that would hold 2.0 moles of 3.0M KI?

c. Calculate the percent by mass of a solution containing 50g of KNO3 in 250g of water.

d. Calculate the percent by mass of a solution containing 25.0g of NaClO3 in 250g of solution.

e. Calculate the parts per million of a solution containing 5.0g of KNO3 in 25000g of water.

f. Calculate the parts per million of a solution containing 1.25g of KNO3 in 100, 000g of solution.

Colligative PropertiesWhen a solute is added to a liquid the IMF increase and the liquid refuses to change phases. Therefore the boiling point increases and the freezing point decreases. Look for the most ions to do the most damage. Watch out for covalent solutes that will remain as one particle, not ionize.

a. Which solution will have the highest boiling point?4M NaCl 2M CO2 1M Mg3(PO4)2 1.5M KI

b. Which solution will have the lowest freezing point?NaCl CO2 Mg3(PO4)2 KI

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Key Idea Question Justify your answerwith an explanation or calculation.

Confidence Level

None Moderate Fully

1 Which changes will make a real gas deviate from ideal gas behavior?

a. High temp, low pressureb. High pressure, low tempc. High pressure and temp

Pre-discussion:

Post discussion:

2 What is the normal boiling point of propanone?

a. 55C c. 101.3kPab. 60C d. 55kPa

Pre-discussion:

Post discussion:3 Which of the following substances have

an inverse relationship between solubility and temperature?

a. HCl c. KIb. KNO3 d. NaCl

Pre-discussion:

Post discussion:

4 When added to water, which of the following substances will raise the boiling point of the water the most?

a. KI b. CH4 c. MgCl2

Pre-discussion:

Post discussion:5 Which of the following could be a

precipitate in a double replacement reaction?

a. KNO3 c. PbI2

b. NH4Cl d. Ca(OH)2

Pre-discussion:

Post discussion:

6 Sketch graphs to show the relationships between pressure and volume, volume and temperature, & pressure and temperature.

Pre-discussion:

Post discussion:7 A solution of KClO3 is saturated at

30C.How many more grams can be dissolved when the solution is heated to 70C?

Pre-discussion:

Post discussion:8 Calculate the percent by mass of a

solution containing 34g of KF dissolved in 250g of water.

Pre-discussion:

Post discussion:9 A solution of salt (NaCl) is created using

78g of solute dissolved in 300mL of solution. Calculate the molarity.

Pre-discussion:

Post discussion:10 Calculate the ppm of a solution created

with 0.0020 g of solute dissolved in 300.0 g of solution.

Pre-discussion:

Post discussion:

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Common Sense Chemistry Review Volume 8Chemistry Matters

1. Explain what makes this cartoon “funny” to chemists.

2. A balloon at room temperature and atmospheric pressure filled with helium has the same number of molecules as the same sized balloon in the same room but filled with CO2. Why does the Helium balloon float and the CO2 balloon sink?

3. Imagine what would happen if a substance were to bubble out of one's blood like carbon dioxide bubbling out of a soda can. This is exactly what can happen to an undersea diver who returns to the surface too quickly: nitrogen rises up within the body, producing decompression sickness—known as "the bends." This condition may manifest as itching and other skin problems, joint pain, choking, blindness, seizures, unconsciousness, permanent neurological defects such as paraplegia, and possibly even death. If a scuba diver descending to a depth of 45.72 m or more were to use ordinary air in his or her tanks, the results would be disastrous. The high pressure exerted by the water at such depths creates a high pressure on the air in the tank, meaning a high partial pressure on the nitrogen component in the air. The result would be a high concentration of nitrogen in the blood, and hence the bends. Instead, divers use a mixture of helium and oxygen. Helium gas does not dissolve well in blood, and thus it is safer for a diver to inhale this oxygen-helium mixture. At the same time, the oxygen exerts the same pressure that it would normally—in other words, it operates in accordance with Dalton's observations concerning partial pressure. If the scuba tank reads a pressure of 3000psi (pounds per square inch) and Helium makes up 2100psi, how much pressure does the oxygen exert?

4. Water normal boils at 100C. But at higher altitudes the water boils at lower temperatures and food is harder to cook. Many people choose to use pressure cookers to heat their food. How will the pressure cooker work to cook the food?

5. Many houses are supplied with “hard” water, water containing calcium ions that when mixed with carbonate ions create “lime buildup” in your showers, sinks, and cooking appliances. What phase is the calcium carbonate? Why doesn’t it just wash down with the water when you shower?

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6. Soda cans are considered to be supersaturated solutions of carbon dioxide in sugar water. How will more CO2 dissolve than the water solution can hold?

7. A student wants to brine this holiday turkey with poultry salt, potassium chloride. If the student is using 400mL of water and boiling the water at atmospheric pressure, how much potassium chloride should initially saturate the solution? (Side question: Why “initially”? What happens to the solubility of the salt and the boiling point of the water as the salt is added?)

8. Farts can be deadly. Farts contain hydrogen sulfide gas, which as concentrations of 15ppm or greater, can be toxic. What volume of hydrogen sulfide gas must be present in the fart if the total fart has a volume of 90mL?

9. Certain water based solutions do not freeze in the freezer at waters normal freezing point such as alcohols and sodas. Anti-freeze is a water based solution added to cars to keep the motor running smoothly in the winter. How do these solution resist freezing?

10. Like many developing countries, Vietnam is plagued by poor water quality — millions of the country's inhabitants still lack access to clean drinking water, largely because local companies can't afford expensive filtration systems to treat wastewater. A team of scientists has found that pouring metal and acid-laden water over a bed of crushed clam or mussel shells provides an easy fix. The shells are made of aragonite, a form of calcium carbonate (CaCO3) that readily swaps out its calcium atoms in favor of heavy metals, locking them into a solid form. Explain how the carbonate and heavy metals in the water such as Mercury, react and can be eliminated from the drinking water.

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Net Ionic Equations Activity1. Observe the reaction between aqueous cobalt (II) nitrate and aqueous sodium carbonate. Imagine how they

look at the molecular level.

a. Write the molecular equation for this reaction:

b. Write the balanced net ionic equation for this reaction:

c. What is/are the spectators in this reaction?

d. What is the precipitate’s name?

e. Draw the reactants before the reaction. (You need at least 3 molecules/ions of each substance present in each beaker and be mindful of the placement of your drawings.)

f. Draw the products after the reaction. (Be aware of how many of each ion you started with.)

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Key


2. Observe the reaction between aqueous Barium chloride and sodium sulfate. Imagine how they look at the molecular level.







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3. Observe the reaction between aqueous copper (II) chloride and sodium carbonate. Imagine how they look at the molecular level.







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4. Observe the reaction between aqueous lead (II) nitrate and sodium iodide. Imagine how they look at the molecular level.







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Molarity of Solutions Web Quest

Open a browser and go to www.phet.colorado.edu. Go to the “Concentration” simulation under the “Chemistry” simulations. Play with this simulation by adding salt, adding drops, adding water, removing water, and evaporating water; all along the way using the concentration meter. Then answer the questions below.

1. What are the ways that enable you to increase the concentration of a solution?

2. What are the ways that enable you to decrease the concentration of a solution?

Now go to the “Salts and Solubility” simulation under the “Chemistry” simulations. Play with this simulator by adding salt until a precipitate forms, adding and removing water to various solutions, all along noting the values in the top right corner. Then answer the questions below.

3. In the boxes below, draw what you see if sodium chloride solutions are saturated, unsaturated, and supersaturated.

4. What is the most common way to measure concentration of a solution?

5. Compare and contrast dilute and concentrated versus unsaturated, saturated, and supersaturated. Use pictures if that is helpful for you.

6. What are the factors that allow you to increase the dissolving rate of a solution?

Now go to the “Molarity” simulation under the “Chemistry simulations”. Click the “show values”. In this simulation, we are assuming that the temperature is set constantly at 25oC. During this simulation, you are going to determine the number of grams for each sample of chemical. Use the following parameters: You have 0.50 L of substance (set the slider appropriately). You will choose the numbers of moles (using the slider appropriately) to change the molarity of your solution. You cannot use drink mix because you cannot write the chemical formula for drink mix, unless you assume that it is sugar.

7. For each of the six solutions, record the moles you choose and the Molarity and then solve for the mass. Substance Moles (mol) Volume (L) Molarity (M) Grams (g)

(A) Cobalt (II) nitrate 0.50L

(B) Cobalt (II) chloride 0.50L

(C) Potassium dichromate 0.50L

(D) Nickel (II) chloride 0.50L

(E) Copper (II) sulfate 0.50L

(F) Potassium permanganate 0.50L

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Unsaturated Saturated Supersaturated

http://www.phet.colorado.edu/


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