UNIT 8: SOLUTIONS. Essential Question: What kinds of properties affect a chemical s solubility?

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1 UNIT 8: SOLUTIONS Essential Question: What kinds of properties affect a chemical s solubility?

2 SOLUTIONS & THEIR CHARACTERISTICS (5) Most chemical reactions take place IN solutions 1. Homogeneous mixture of substances in the same physical state (solid, liquid, gas) *LIQUIDS* atoms, ions, or molecules of one substance spread UNIFORMLY throughout a second substance Ex) SALT (NaCl) stirred into water NaCl = SOLUTE: substance being dissolved (smaller amt) H 2 O = SOLVENT: substance that dissolves solute (greater amt) water = most common solvent, making solutions aqueous (aq) REACTION: NaCl (s) à Na + (aq) + Cl - (aq)

3 SOLUTIONS & THEIR CHARACTERISTICS (5) 2. CLEAR (transparent) and DON T disperse light a. particles in solutions are too small to do so 3. CAN have color à transition metals have color! 4. WILL NOT settle on standing (like salt in water) a. once dissolved, it remains in aqueous form 5. WILL pass through a filter

4 SOLUBILITY The measure of how much of a substance can dissolve in a given amount of solvent and at a given temperature SOLUBLE: able to be dissolved in solvent MOST concentrated* INSOLUBLE: does NOT dissolve in solvent LEAST concentrated*

(animation) Description: Na+ is attracted to O- in H 2 O & Cl- is attracted to

5 WHAT CAN DISSOLVE? Ex) NaCl = ionic bond H 2 O = Polar Molecule NaCl dissociation in Water (animation) Description: Na+ is attracted to O- in H 2 O & Cl- is attracted to H+ in H 2 O the forces between these two ions are greater than that of Na with Cl RESULT = the bond BREAKS & the salt DISSOLVES! **LIKE DISSOLVES LIKE!**

6 WHAT CAN DISSOLVE? Why doesn t grease wash off easily with JUST water? Water = polar, so NEED soap (polar and non-polar ends) that enable it to dissolve in water & the grease SOLUTE TYPE NONPOLAR SOLVENT POLAR SOLVENT Nonpolar Soluble INsoluble Polar INsoluble Soluble Ionic INsoluble Soluble PREDICT & ARGUE ACTIVITY

7 TABLE F ~ SOLUBILITY GUIDELINES determines which substances are soluble v. Insoluble predicts if a precipitate will form when two ionic solutions are mixed/undergo double replacement rxn PRECIPITATE: (solid product) will form if one/both products is/are INSOLUBLE! *check reference table* Examples: KNO 3 CaCO 3.MgSO 4 Soluble Insoluble Soluble Silver nitrate & sodium chromate solutions are mixed together. What are the products & are they precipitates? Reaction: 2AgNO 3 + Na 2 CrO4 à Ag 2 CrO 4 + 2NaNO 3 à silver chromate = Precipitate!

8 USE REFERENCE TABLE F TO DETERMINE WHETHER THE FOLLOWING COMPOUNDS ARE SOLUBLE OR INSOLUBLE KBr PbCO 3 BaSO 4 KOH Zinc Hydroxide Sodium Acetate Cadmium (II) Sulfide Silver Acetate Zinc Carbonate SOLUBLE INSOLUBLE INSOLUBLE SOLUBLE INSOLUBLE SOLUBLE INSOLUBLE SOLUBLE INSOLUBLE

9 IDENTIFY THE 2 NEW COMPOUNDS FORMED VIA THE FOLLOWING REACTIONS & IDENTIFY ANY PRECIPITATES AgNO 3 + KBr BaCl 2 + Na 2 CO 3 2 Al(NO 3 ) CaS CuSO NH 4 OH AgBr + KNO 3 2 NaCl + BaCO 3 3 Ca(NO 3 ) 2 + Al 2 S 3 (NH 4 ) 2 SO 4 + Cu(OH) 2

TABLE G ~ SOLUBILITY CURVES Y-Axis à # grams of a substance that can be dissolved in 100 g water X-Axis à temperature in o C between 0 & 100 Curves represent the MAX amount of a substance that can be

10 TABLE G ~ SOLUBILITY CURVES Y-Axis à # grams of a substance that can be dissolved in 100 g water X-Axis à temperature in o C between 0 & 100 Curves represent the MAX amount of a substance that can be completely dissolved in a given temperature SOLIDS = lines going upward/increasing GASES = lines going downward/decreasing Temperature: increase temp, most solids become soluble except GASES = react opposite!! Pressure: increase pressure, gases more soluble ex) SODA CAN à what happens when it s opened? (gas released ~ increased volume & decreased pressure) *HIGH TEMP/LOW PRESSURE = prime conditions for solids

11 TABLE G ~ SOLUBILITY CURVES Which point(s) on the graph are: Unsaturated, Saturated, Supersaturated Unsaturated = A Saturated = B & C Supersaturated = D CONCLUSIONS: Below Curve = unsaturated On Curve = saturated Above Curve = supersaturated

12 TABLE G ~ SOLUBILITY CURVES Table G Practice whole class: How many grams of NaCl will dissolve in 100g H 2 O at 90 o C? 40g Is a solution made up of 100g H 2 O and 70g KNO 3 at 50 o C saturated, unsaturated, or supersaturated? Unsaturated (below curve under the given conditions) Now it s YOUR turn!

13 USE REFERENCE TABLE G TO ANSWER THE FOLLOWING: 1. List the substances whose solubility decreases as temperature increases 2. Which substance is LEAST affected by temperature change? 3. How many grams of ammonium chloride can be dissolved at 50 o C? 1. NH 3 SO 2 HCl 2. NaCl 3. ~53g

14 4. Which compound is LEAST soluble in water at 10 o C 5. Are the following solutions unsaturated, saturated, or supersaturated? a. 45 g KNO 3 in 100g H 2 O at 30 o C b. 60 g KClO 3 in 100g H 2 O at 90 o C? 4. KClO 3 5. A) Saturated B) Supersaturated

15 6. At what TEMP would 25g of potassium chlorate dissolve? 7. What s the solubility of KNO 3 & NH 3 at 55 o C under the following conditions: à Total solvent of water is = 100g // 200g // 25g // 50g o C 7. KNO 3 = ~95g/ ~190g ~23.75g/~48g NH 3 = ~25g/~50g/ ~6.25g/~12.5g

16 SOLUTION CONCENTRATIONS (TABLE T) How do YOU like your iced tea? Lemonade? Dilute: solute/solvent (weak solution) Concentrated: SOLUTE/solvent (strong solution) MOLARITY: table T! Moles solute/1 L solution ex) What is the molarity of a solution that contains 4.0 mol of NaOH in 0.50 L of solution? 8.0 M What is the molarity of a solution containing 82.0g of Ca(NO 3 ) 2 in 2.0 liters of solution? M

17 SOLUTION CONCENTRATIONS (TABLE T) What mass of sodium carbonate is required to prepare 2.00L of a M sodium carbonate solution? V = 2.00L M = M moles =? sodium carbonate = Na 2 CO 3 molar mass = 106 g Molarity = moles L M = x L x = 0.5 moles Na 2 CO 3 à convert to grams! *(0.5moles)(106g) = 53 grams*

18 PERCENT BY MASS (TABLE T) What is the percent by mass of sodium hydroxide if 2.5g of NaOH is added to 50.00g of H 2 O? FORMULA: table T! (mass of part / mass of whole) x 100 part = 2.5 g whole = 50.00g + 2.5g = 52.50g (2.5g / 52.50g) x 100 = x = x 100 = 4.76%

19 PERCENT BY VOLUME (TABLE T) What is the percent by volume of alcohol if 50.0 ml of ethanol is diluted with water to form a total volume of ml? FORMULA: table T! (volume of solute/ volume of solution) x 100 vol. of solute = 50.0 ml vol. of solution = ml (50.0 ml / ml) x 100 = x = x 100 = 16.7 %

20 PARTS PER MILLION (TABLE T) Approximately g of oxygen can be dissolved in ml of water at 20 o C. Express this in terms of parts per million. FORMULA: table T! *water = 1g/mL* (grams of solute/ grams of solution) x 1,000,000 ppm grams of solute = g vol. of solution = g ( g / 100.0g) x 1,000,000 = x = x 1,000,000 = 43 ppm

21 COLLIGATIVE PROPERTIES SoOoO why does salt lower the freezing point of water? Actually à it doesn t matter WHAT the substance is, what matters is the total # of dissolved particles Freezing Point: 1 mole of any particle LOWERS the F.P. of water Boiling Point: (same as FP) but RAISES the B.P. of water Molecular v. Ionic Compounds: separated ions affect freezing points per mole quantity formed aka the GREATER # of ions, the GREATER effect on freezing point ex1) NaCl(s) à Na+(aq) + Cl-(aq) 1 mole NaCl à 1 mole Na + 1 mole Cl ex2) CaCl 2?? à 1 mol Ca & 2 mol Cl = 3 mol total ex3) C 12 H 22 O 11 à C 12 H 22 O 11 (aq) 1 mole à 1 mole

22 COLLIGATIVE PROPERTIES What is VAPOR? (link back to matter heating curves!) when solids/liquids enter gaseous phase at room temp VAPOR PRESSURE: caused by evaporation pressure is exerted by molecules escaping off a liquid into the gas phase TEMP ñ, VAPOR PRESSURE ñ BOILING POINT: (of a liquid) the temp at which the vapor pressure is kpa or 1atm (standard atmospheric pressure) Take a look at table H!

Name: Regents Chemistry: Dr. Shanzer. Practice Packet. Chapter 11: Solutions

Name: Regents Chemistry: Dr. Shanzer Practice Packet Chapter 11: Solutions What are Solutions? Objective: How do we recognize the parts of a solution, its characteristics and the difference between dissolving