Portage Learning - CHEM 103 MODULE 6 Exam, Exams of Chemistry

Download Portage Learning - CHEM 103 MODULE 6 Exam and more Exams Chemistry in PDF only on Docsity!

Portage Learning - CHEM 103 MODULE 6 Exam

Question 1

10 / 10 pts

Question 2

3 / 10 pts

You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Links to an external site. Why do granulated sugar crystals dissolve more quickly than sugar cubes? Granulated sugar crystals dissolve more quickly since they are smaller crystals with a greater surface area since solids leave the surface of their bulk solids to dissolve. You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Links to an external site. Explain why water boils at 100 oC rather than from 100 oC to 101 oC? Your Answer: When water reaches 100 oC, the temperature remains constant since all of the energy being added is being used to overcome forces of attraction between the particles and separate them so the temperature does not rise. the temperature remains constant since all of the energy being added is being used to overcome forces of attraction between the particles and separate them

Calculator Periodic Table Equation Table Links to an external site.

Question 5

6 / 10 pts

Question 6

10 / 10 pts

Show the calculation of the mass percent solute in a solution of 18.9 grams of^ Ba(MnO 4 ) 2 in^400 grams^ of^ water.^ Report^ your answer to 3 significant (^) figures. Mass % = (gsolute / gsolute + gsolvent) x 100 % Mass % = (18.9 / 18.9 + 400) x 100 = 4.51% You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Links to an external site. Show the calculation of the molality of a solution made by dissolving 27.5 grams^ of^ C 7 H 14 O 7 in^350 grams^ of^ water.^ Report^ your answer to 3 significant (^) figures. molality = (gsolute / MW) / (gsolvent / 1000 ) molality = (27.5 / 210.182) / (350 / 1000) = 0.374 m You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Links to an external site. Show the calculation of the molarity of a solution made by dissolving 29.7 grams^ of^ Ba(MnO 4 ) 2 to^ make^250 ml^ of^ solution.

Question 7

6 / 10 pts

Question 8

10 / 10 pts

Molarity = (29.7 / 375.41) / (250 / 1000) = 0.316 M You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Links to an external site. Show the calculation of the mass of Mg(NO 3 ) 2 needed to make 200 ml of a 0.250 M solution. Report your answer to 3 significant figures. Your Answer: Molarity = (moles) / (mlsolvent / 1000 ) 0.250 = (moles) / (200 / 1000) Moles = 0.250 x 0.200 = 0. Moles = (gsolute / MW) 0.05 00 = (gsolute / 148.3 25 ) gsolute = 0.050 0 x 148. 325 = 7. 42 g You may find the following resources helpful: Scientific Calculator

Periodic Table Equation Table Links to an external site.

molality = (34.6 / 210.182) / (200 / 1000) = 0.823 m

Question 10

6 / 10 pts

∆tf = Kf x m = 1.8 6 x 0.82 3 = 1.5 3 oC FPsolution = FPsolvent - ∆tf = 0 oC – 1.5 3 = - 1. 53 oC You may find the following resources helpful: Scientific Calculator Periodic Table Equation Table Links to an external site. Show the calculation of the molar mass (molecular weight) of a solute if a solution of 12.5 grams of the solute in 200 grams of water has a freezing point^ of^ - 1.3^0 oC.^ Kf for^ water^ is^ 1.8^6 and^ the freezing point of pure water is 0 oC. Calculate your answer to 0. 1 g/mole. ∆tf = Kf x m molality = ∆tf / Kf = 1.3 0 / 1.8 6 = 0.69 9 m molality = (gsolute / MW) / (gsolvent / 1000 ) 0.699 = (moles) / (200 / 1000) Moles = 0.699 x 0.200 = 0. 0.1398 = (12.5 / MW)