Ch5_D_Solutions - REACTIONS IN SOLUTION Section 5.5...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: REACTIONS IN SOLUTION Section 5.5 PROBLEM: Dissolve 5.00 g of NiCl 22•6 H22O in PROBLEM: Dissolve 5.00 g of NiCl •6 H O in enough water to make 250 mL of solution. enough water to make 250 mL of solution. Calculate molarity. Calculate molarity. Terminology Terminology In solution we need to define the • SOLVENT the component whose physical state is preserved when solution forms • SOLUTE the other solution component The Nature of the KMnO 44 Solution The Nature of the KMnO Solution Step 2: Calculate molarity Step Calculate [NiCl2•6 H2O ] = 0.0841 M Molarity(M) = moles solute liters of solution The Nature of a Na 22CO33 Solution The Nature of a Na CO Solution 3 Na 2CO3 Na 1 mol = 0 .0210 mol 237.7 g 0.0210 mol = 0 .0841 M 0.250 L The amount of solute in a solution is given by its concentration. is concentration This water-soluble compound is ionic Na2CO3(aq) --> 2 Na+(aq ) + CO32-(aq) Step 1: Calculate moles Step Calculate of NiCl2•6H2O 5.00 g • Concentration of Solute Concentration of Solute KMnO4(aq) --> K+(aq) + MnO4-(aq) If [KMnO4 ] = 0.30 M, then [K+] = [MnO 4-] = 0.30 M Page 1 If [Na2CO3] = 0.100 M, then [Na+] = 0.200 M [CO32-] = 0.100 M USING MOLARITY USING MOLARITY USING MOLARITY USING MOLARITY What mass of oxalic acid, H 2C2O4, is required to make 250. mL of a 0.0500 M solution? Because Conc (M) = moles/volume = mol/V this means that moles = M • V What mass of oxalic acid, H2C2O4, is What required to make 250. mL of a 0.0500 M solution? moles = M • V Step 1: Calculate moles of acid Step Calculate required. (0.0500 mol/L)(0.250 L) = 0.0125 mol Step 2: Calculate mass of acid Step Calculate required. (0.0125 mol )(90.00 g/mol) = PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What NaOH and you want 0.50 M NaOH. What do you do? do you do? Add water to the 3.0 M solution to lower its concentration to 0.50 M Dilute the solution! 1.13 g 1.13 PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What NaOH and you want 0.50 M NaOH. What do you do? do you do? H2 O But how much water But do we add? do Preparing Solutions Preparing Solutions • Weigh out a solid solute and dissolve in a given quantity of solvent. • Dilute a concentrated solution to give one that is less concentrated. PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What NaOH and you want 0.50 M NaOH. What do you do? do you do? How much water is added? The important point is that ---> moles of NaOH in ORIGINAL solution = moles of NaOH in FINAL solution 3.0 M NaOH Concentrated 0.50 M NaOH Dilute Page 2 PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What NaOH and you want 0.50 M NaOH. What do you do? do you do? PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What NaOH and you want 0.50 M NaOH. What do you do? do you do? Moles of NaOH in original solution = M•V = Conclusion: H2 O add 250 mL of water to (3.0 mol/L)(0.050 L) = 0.15 mol NaOH Therefore, moles of NaOH in final solution must also = 0.15 mol NaOH (0.15 mol NaOH)(1 L/0.50 mol) = 0.30 L or 300 mL = volume of final solution or 300 3.0 M NaOH Concentrated 50.0 mL of 3.0 M NaOH to make 300 mL of 0.50 M 0.50 M NaOH NaOH. Dilute Page 3 Preparing Solutions Preparing Solutions by Dilution by Dilution A shortcut Minitial • Vinitial = Mfinal • Vfinal ...
View Full Document

Ask a homework question - tutors are online