HONORS CHEMISTRY 1. Name: Mods: Chemistry Work - Solutions

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1 HONORS CHEMISTRY 1 Name: Mods: Chemistry Work - Solutions

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7 HONORS CHEMISTRY 7 Name Date 1. What is the solubility of sodium nitrate at 45 o C? 2. What is the solubility of salt at 20 o C? 3. How many grams of potassium nitrate can you dissolve in 100 cm 3 of water at 50 o C? 4. How many grams of potassium chlorate can you dissolve in 100 cm 3 of water at 100 o C? 5. At what temp are the solubilities of sodium chloride and potassium nitrate the same? 6. At what temp are the solubilities of sodium chloride and sodium nitrate the same? 7. How much sodium nitrate can you dissolve in 40 cm 3 of water at 100 o C? 8. How much salt can you dissolve in 20 cm 3 of water at 60 o C? 9. If 100. cm 3 of a saturated solution of sodium nitrate is cooled from Cto room temp (20. 0 C), How much sodium nitrate precipitate will form at the bottom of the solution? 10. If a 50.cm 3 of a saturated solution of potassium nitrate at 15 0 C is heated to 50 0 C, how much more potassium nitrate can dissolve.

8 HONORS CHEMISTRY 8 Name: Date: Mole Houses! The moles of room 335 are in a huge fight. They are arguing about who is living in the most crowded conditions. Of course, the most crowded moles will have the highest molarity. Help the moles solve their dilemma. HOUSE 1 M = = HOUSE 2 M = = HOUSE 3 M = = HOUSE 4 M = = HOUSE 5 M = = HOUSE 6 M = = HOUSE 7 M = = HOUSE 8 M = = HOUSE 9 M = = HOUSE 10 M = = Which moles have the most crowded living conditions?? Solve the following problems grams of NaOH is dissolved in 3.5 L of solution grams of NaCl is dissolved in 2.1 L of solution.

9 HONORS CHEMISTRY 9 Name: Date: Molarity 1. How do you make 3.5 L of a 4.5 M solution of Mg(OH)2. 2. How do you make 2.1 L of a.75 M solution of Al(NO3)3. 3. How do you make.35 L of a 1.5 M solution of BaCl g of NaCl is dissolved in 500 ml of water. What is the molarity? g of NaOH is dissolved in 350 ml of water. What is the molarity?

10 HONORS CHEMISTRY 10 Name Molarity Lab Calculate how many grams of NaCl you will need to add to water in order to make solutions of the given molarities. Solution #1: 0.25 M solution in a 2000 ml flask. Solution #2: 0.50 M solution in a 500 ml flask. Solution #3: 0.75 M solution in a 1000 ml flask. Solution #4: 1.00 M solution in a 250 ml flask. Solution #5: 1.25 M solution in a 25 ml flask. Solution #6: 1.50 M solution in a 10 ml flask.

11 HONORS CHEMISTRY 11 Solution #7: 1.75 M solution in a 100 ml flask. Solution #8: 2.00 M solution in a 50 ml flask. Solution #9: 2.25 M solution in a 100 ml flask. Solution #10: 0.25 M solution in a 25 ml flask. Solution #11: 1.25 M solution in a 100 ml flask. Solution #12: 2.25 M solution in a 25 ml flask.

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16 HONORS CHEMISTRY 16 Name: Colligative Properties Practice FOR WATER Kf = 1.86 o Ckg/mol Kb =.51 o Ckg/mol Date: 1. Consider the following solutions: m Na3PO4 in water m CaBr2 in water m KCl in water m HF in water (HF does not dissociate much b/c it is a weak acid) A. Highest freezing point B. lowest freezing point C. Highest boiling point D. Lowest boiling point 2. From the following: Pure water Solution of C12H22O11 (m =0.01) in water Solution of NaCl (m = 0.01) in water Solution of CaCl2 (m = 0.01) in water Choose the one with the A. Highest freezing point B. lowest freezing point C. Highest boiling point D. Lowest boiling point

17 HONORS CHEMISTRY Calculate the freezing point and boiling point of each of the following solutions using the observed van t Hoft factor. A m MgCl2 B m FeCl3 4. Calculate the freezing point and boiling point of an antifreeze solution that is 50.0 g ethylene glycol (HOCH2CH2OH) in 50.0 g water. Ethylene glycol is a nonelectrolyte. 5. What mass of glycerine (C3H8O3), a nonelectrolyte, must be dissolved in g water to give a solution with a freezing point of o C?

18 HONORS CHEMISTRY 18 Name: Date: The molecular weight and formula of a hydrocarbon are to be determined through the use of the freezing point depression method. The hydrocarbon is known to be 86% carbon and 14% hydrogen by mass. In the experiment, 3.72 grams of the unknown hydrocarbon were placed into 50.0 grams of liquid benzene, C6H6. The freezing point of the solution was measured to be 0.06 o C. The normal freezing point of benzene is 5.50 o C and the freezing point depression constant for benzene is 5.12 o C/m. A. What is the empirical formula for the hydrocarbon? Calculate the molar mass for this empirical formula. B. Calculate the freezing point depression C. Calculate the molality of the solution D. Calculate the moles of hydrocarbon added to the benzene E. Calculate the molar mass (g/mole) of the hydrocarbon F. What is the molecular formula for the hydrocarbon

19 HONORS CHEMISTRY 19 Name: Date: A. The molecular weight and formula of a hydrocarbon are to be determined through the use of the freezing point depression method. The hydrocarbon is known to be 85.7% carbon and 14.3% hydrogen by mass. The hydrocarbon dissolves readily in CCl4. A solution prepared by mixing 135 grams of CCl4 and 4.36 grams of the hydrocarbon has a boiling point of 78.7 o C. The molal boiling point elevation constant of CCl4 is 5.02 o C/molal, and its normal boiling point is 76.8 o C. Calculate the molecular weight of the hydrocarbon. A. What is the empirical formula for the hydrocarbon? Calculate the molar mass for this empirical formula. B. Calculate the boiling point elevation C. Calculate the molaltiy of the solution D. Calculate the moles of hydrocarbon added to the benzene E. Calculate the molar mass (g/mole) of the hydrocarbon F. What is the molecular formula for the hydrocarbon

20 HONORS CHEMISTRY 20 Name Date REVIEW SOLUBILITY 1. is the substance that is dissolved. 2. is the substance that does the dissolving. 3. is a homogeneous solution. 4. A solution has the maximum amount of solute dissolved in a given amount of solvent. 5. A solution can dissolve more solute. 6. Opposite of soluble is. 7. is how many grams of solute dissolves in 100 cm 3 of water. 8. For most solid solutes, as temperature goes up, solubility goes 9. For most gas solutes, as temperature goes up solubility goes 10. Discuss thermal pollution and its affects on gas solubility: 11. What is the solubility of NaCl at 25 o C? 12. What is the solubility of KNO3 at 70 o C? 13. At what temperature is the solubility of KNO3 20g/100cm 3 H2O?

21 HONORS CHEMISTRY At what temperature is the solubility of NaNO3 90g/100cm 3 H2O? 15. How many grams of KClO3 dissolves in 100 cm 3 H2O at 30 o C? 16. How many grams of KNO3 dissolves in 100 cm 3 H2O at 50 o C? 17. How many grams of KCl will dissolve in 40 cm 3 H2O at 80 o C? 18. How many grams of NH3 will dissolve in 500 cm 3 H2O at 80 o C? 19. How many grams of KNO3 will dissolve in 250 cm 3 H2O at 50 o C? 20. If 30 grams of KNO3 are dissolved in 100cm 3 H2O at 20 o C, will the solution be saturated or unsaturated? Explain why?

22 HONORS CHEMISTRY 22 REVIEW MOLARITY, MOLALITY, MASS PERCENT 21. How many moles of Na3PO4 are needed to make ml of a 0.50 M solution? 22. What is the molarity of a solution containing g of H3PO4 dissolved in ml of solution? 23. How many grams of calcium oxide are needed to make 50.0 ml of a 0.75 M solution? 24. How many liters of solution are needed to dissolve 25.5 g hydrogen phosphate if a concentration of 0.25 M is needed? 25. What is the nitrate ion concentration if g of barium nitrate are dissolved in 500. ml of solution? 26. How many grams of H2SO4 were dissolved in ml of solution if the final hydrogen ion concentration is 0.25 M?

23 HONORS CHEMISTRY Calculate the molality of a solution of 50.0 g nickel (II) chloride in g of water g barium chloride dissolves in 250. ml of water. Calculate the mass percent concentration. 29. What is the new boiling point is 25.0 g of calcium chloride is dissolved in 500. ml of water? 30. When 10.0 g of a nonelectrolyte is added to 50.0 g of water, the new freezing point is o C. What is the molecular mass of the unknown compound?

24 HONORS CHEMISTRY 24 Lab Freezing Point Depression Procedure: 1) Mass out 5.00 g of naphthalene and place it in a test tube 2) Place test tube containing naphthalene in a beaker of water and heat until all the solid has melted 3) Remove the test tube from the water bath and begin recording the temperature using data studio on the computer (remember to continuously stir the liquid in the test tube) 4) Continue to record the temperature until all the liquid has frozen 5) Place the test tube back in the water bath and re-melt the solid 6) Mass out g of unknown and add it to the liquid in the test tube 7) Repeat steps 3-5 above 8) Remove and clean the thermometer 9) Place the test tube (with contents) in the beaker in the fume hood 10) Calculate the freezing point depression 11) Calculate the molar mass of the unknown solid Data: Mass of naphthalene (solvent) Mass of unknown (solute) Freezing point for pure naphthalene Freezing point for naphthalene and unknown solute Calculations: 1) Freezing point depression 2) molality of solution 3) moles of solute 4) molar mass of solute