Question

( PNP End-of-Chapter exercises: 3.47, 51, 55, 57, 59, 61, 65, 67, 71, 73, 75, 77, 79 2 520 1. What is the molarity of a solution prepared by dissolving 14.2 mL of acetic acid, HC2H2O2, in 100.00 mL of water? The density of acetic acid is 1.008 g/mL. acetic acid (2) 1.6o6gallmola 0.2365 mol 0.2345 =2.365 M IlmLa 160.0529 2. What volume of water, in ml, must be added to 415 mL of 0.0525 M HCl in order to make a 0.0255 M solution? M V,: Metz M = 0.025 3 10.0525) (4115)=0.0255\U2) ? V2 = 654 m2 M20.025s 2 2 5/ 2709 -0.025s (U2OSS The ethanol content of alcoholic beverages is given in units of "proof," which is double the amount of ethanol (C2H5OH) by volume (for example, a 60 proof alcohol is 30% ethanol by volume). What is the concentration in molarity and mass fraction of 94 proof brandy? The density of ethanol is 0.78945 g/cm at 20°C. 12.75 mL of a 12.1-M stock solution of Na,SO, is diluted to 1.5 L. An additional 5.0 g NaCl is added to the solution. What is the concentration of sodium ions in the resulting solution (assume the volume of the solid NaCl is negligible)?

I really need someone to explain 3 and 4. I don't understand it. If you're feeling generous, would you also mind checking my work for questions 1 and 2?

Thank you!

Answer 1

First question us right. In second question V2 is the total volume, so volume to be added=854-415= 439 ml

Modlarity = no. of moles of ethanol (n) U volume of solution in a in= mass of ethanol (m) Molar mass of ethanol (M) 94 %oop bezandy means 47% ethanol. This means If there is total 100 mL volume of solution then 47 ml us ethanol and 53 mL is water. Density of ethanol us 0.78945 g/mL. So ImL has mass = 0.789459 47mL has mass = 0.78945x47-370104159 So moes of ethanol = 37,104158 =0.80539 mola - 460079/mol - volume of solution - 100 ml = 0.100L.so este - 0.80539 mot 18.0539 mol/L U 0.1DOL T Mass fraction mass of ethanol mass of solution (ethanol twater) e Density of water at 20% is 0.99823 g/mL so i ImL of H₂O has mas = 0.998939 st 53mL has mass = 0.99823x53=58.90619 | mass of solution = 52.90619+ 37.10415 = 90.010349 ♡ Mass fraction = 37.10415g. To 90.01034 g