Reviewunit 4 Test(Chp 4): Aqueous Reactions and Solution Stoichiometry

Name: ______Date: ______Period: ____

REVIEWUnit 4 Test(Chp 4): Aqueous Reactions and Solution Stoichiometry

Multiple Choice (20 questions)(50% of score)

polyatomic ions (names, charges, formulas)

6 strong acids (what does it mean to say a “strong” “acid” ?)

strong bases (group I and Ca, Ba, Sr with hydroxide, OH–) (what is a “strong” “base” ?)

electrolytes (strong, weak, non) (and what particles are actually in solution)

ALWAYS soluble ions (Group I , NH4+ , NO3–)

NET ionic equations (comp – diss – cross – net – bal)

oxidation numbers of elements in compounds (like what is the ox. # of C in oxalate ion C2O42– ?)

redox reactions (LEO says GER)

activity of metals (which metals are least active – or – which metals do not lose electrons as easily)

gas forming reactions ( ____ reacted with ____ will form which gas: H2(g) or CO2(g) )

solution stoichiometry with Molarity ( L  g ) ( g  L ) ( g and L M ) ( dilutions M1V1 = M2V2 )

Free Response(32 points)(3 questions)(50% of score)

1)lab question: solution preparation, gravimetric analysis of precipitate to find % by mass (8 pts)

2)lab question: qualitative analysis of unknown solutions by precipitation (9 pts)

3)write 3 NET ionic equations from verbal descriptions, predict products, and balance (15 pts)

Section I Multiple Choice

NO Calculator Allowed

27.Beaker X and beaker Y each contain 1.0 L of solution, as shown above. A student combines the solutions by pouring them into a larger, previously empty beaker Z and observes the formation of a white precipitate.

Assuming that volumes are additive, which of the following sets of solutions could be represented by the diagram above?

Beaker X Beaker Y Beaker Z

(A) 2.0 M AgNO32.0 M MgCl24.0 M Mg(NO3)2 and AgCl(s)

(B) 2.0 M AgNO32.0 M MgCl22.0 M Mg(NO3)2and AgCl(s)

(D) 2.0 M AgNO31.0 M MgCl20.50 M Mg(NO3)2 and AgCl(s)

Section II Free Response

Calculator Allowed

CLEARLY SHOW THE METHODS USED AND STEPS INVOLVED IN YOUR ANSWERS. It is to your advantage to do this, because you may earn partial credit if you do and little or no credit if you do not. Attention should be paid to significant figures.

1. A student is assigned the task of preparing 50. mL of 6 M HNO3 to use in an experiment.

(a) The student is provided with a stock solution of 16 M HNO3 , two 100 mL graduated cylinders that can beread to ±1 mL, a 100 mL beaker that can be read to ±10 mL, safety goggles, rubber gloves, a glassstirring rod, a dropper, and distilled H2O.

(i) Calculate the volume, in mL, of 16 M HNO3 that the student should use for preparing 50. mL of6 M HNO3. (1)

(ii) Briefly list the steps of an appropriate and safe procedure for preparing the 50. mL of 6 M HNO3. Onlymaterials selected from those provided to the student (listed above) may be used. (2)

(iii) Explain why it is not necessary to use a volumetric flask (calibrated to 50.00 mL ±0.05 mL) to performthe dilution. (1)

In a second experiment, a student is given 2.94 g of a mixture containing anhydrous MgCl2 and KNO3. To determine the percentage by mass of MgCl2 in the mixture, the student uses excessAgNO3(aq) toprecipitate the chloride ion as AgCl(s).

(b)Starting with the 2.94 g sample of the mixture dissolved in water, briefly describe the steps necessary to quantitatively determine the mass of the AgCl precipitate. (2)

(c)The AgCl precipitate is filtered, washed, dried, and weighed to constant mass in a filter crucible. The student determines the mass of the AgCl precipitate to be 5.48 g.

On the basis of this information, calculate each of the following.

(i)The number of moles of MgCl2 in the original mixture (2)

(ii)The percent by mass of MgCl2 in the original mixture (1)

2.The identity of an unknown solid is to be determined. The compound is one of the seven salts in the following table.