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7.85 kg KCl are dissolved in 2.38 L of solution. Find molality. 24.8 g table sugar (i.e., sucrose, C 12 H 22 O 11 ) are mixed into 450 g water. Find molality.

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Presentation on theme: "7.85 kg KCl are dissolved in 2.38 L of solution. Find molality. 24.8 g table sugar (i.e., sucrose, C 12 H 22 O 11 ) are mixed into 450 g water. Find molality."— Presentation transcript:

1 7.85 kg KCl are dissolved in 2.38 L of solution. Find molality g table sugar (i.e., sucrose, C 12 H 22 O 11 ) are mixed into 450 g water. Find molality. WRONG

2 1 mol CaF 2 2 atoms F 18 g 6.02 x molecules 1 g1000 mL What mass of CaF 2 must be added to 1,000 L of water so that fluoride atoms are present at a conc. of 1.5 ppm? = 3.34 x m’cules H 2 O X m’cule H 2 O = 1000 L 1 L1 mL 1 mol6.02 x10 23 m’cule 1 mol 1.5 atom F X atoms F 1,000,000 m’cule H 2 O 3.34 x m’cule H 2 O = 1 molecule CaF 2 X = 5.01 x atoms F times =2.505 x molecules CaF 2 1 mol CaF 2 X g CaF 2 = x molecules =3.25 g CaF g CaF 2

3 40.0 g NaOH 1 mol NaOH How many moles solute are required to make 1.35 L of 2.50 M solution? mol = M L B. What mass magnesium phosphate is this? A. What mass sodium hydroxide is this? mol L M 3.38 mol = 2.50 M (1.35 L) = X g NaOH = 3.38 mol NaOH = 135 g NaOH g Mg 3 (PO 4 ) 2 1 mol Mg 3 (PO 4 ) 2 X g Mg 3 (PO 4 ) 2 = 3.38 mol Mg 3 (PO 4 ) 2 = 889 g Mg 3 (PO 4 ) 2

4 0.342 mol 5.65 L Find molarity if 58.6 g barium hydroxide are in 5.65 L solution g Ba(OH) 2 1 mol Ba(OH) 2 Step 2). What is the molarity of a 5.65 L solution containing mol solute? Step 1). How many moles barium hydroxide is this? M Ba(OH) 2 = X mol Ba(OH) 2 = 58.6 g Ba(OH) 2 = mol Ba(OH) 2 M = mol L M =

5 You have 10.8 g potassium nitrate. How many mL of solution will make this a 0.14 M solution? convert to mL

6 Concentration SAWS Water Quality Report - June 2000

7 Molality mass of solvent only 1 kg water = 1 L water

8 Molality  Find the molality of a solution containing 75 g of MgCl 2 in 250 mL of water. 75 g MgCl 2 1 mol MgCl g MgCl 2 = 3.2 m MgCl kg water

9 Molality  How many grams of NaCl are req’d to make a 1.54m solution using kg of water? kg water1.54 mol NaCl 1 kg water = 45.0 g NaCl g NaCl 1 mol NaCl

10 Molarity of Solutions Keys Molarity of Solutions


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