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2010Fchem125-2-exam2answers040ri66

2010Fchem125-2-exam2answers040ri66 - Chem 125 Exam#2 Fall...

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Chem. 125 Exam #2 Fall 2009 PART A. (4 Points each) 1. Which of the following ionic compounds is NOT soluble in water? a. magnesium sulfate, MgSO 4 c. V(CH 3 COO) 3 or V(C 2 H 3 O 2 ) 3 e. VI 3 b. magnesium sulfide, MgS d. potassium carbonate, K 2 CO 3 2. Suppose a person used 1.5 gallons of latex paint to paint 250 ft 2 . What is the thickness of the paint before it cures. (The cured thickness will be substantially less.) Hint: what is the relationship between volume, area, and thickness. Useful information: 1 gallon is approximately 3.79 L, 1L is 1000 cm 3 , 12 inches is 1 foot, and 1 inch is 2.54 cm. 3. 0.65 g beryllium (Be) chloride is dissolved in enough water to make 16 mL of solution. What is the concentration of the chloride ions? Careful! What is the formula of this compound? 4. A 55 mL of 2.33 M HCl is diluted to 350 mL. What is the acid's new concentration? 5. 1.2 L of sulfuric acid is in a container. What is its concentration if 25.0 mL of it is neutralized by 43.0 mL of 1.35 M NaOH? ( ( ( ( 2 4 2 2 4 2 2 . H SO aq NaOH aq H O l Na SO aq + + a. 0.426 M b. 0.674 M c. 2.32 M d. 1.16 M e. 4.64 M ( 29 55 2.33 0.37 350 mL M HCl x M HCl mL = 2 2 2 2 9.01 2 35.45 79.7 / 0.65 1 /0.016 0.510 / 0.510 1 79.7 2 0.510 1.02 1.0 MM BeCl x g mol g BeCl mol BeCl x L mol L M BeCl g Cl x M M - = + = = = = = 2 2 3 3 2 1.5 3.79 10 1 10 0.24 250 12 2.54 vol t area vol t area gal L cm ft in mm x x x x mm ft gal L in cm cm = =   = =     ( ( ( ( 2 4 2 2 4 2 4 2 4 2 4 2 4 3 1.35 0.04 2 2 25.0 mL 43.0 mL ?M 3 1 0.0290 1 2 0.0290 1.16 1. 1.3 16 0.02 5 5 M H SO aq NaOH aq H O l Na SO aq H S mol NaOH L mol x x mol L mol NaOH mol HNO mol Conent O H SO H SO ration M L L H SO = = = = + +
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Chem. 125 Exam #2 Fall 2009 6. A balloon is filled to 3.5 L with helium gas. The pressure is 1.14 atm and the temperature is 300 K. Approximately how many He atoms are in the balloon? 7. A small iron bar is placed in excess nitric acid and is completely consumed according to the following reaction: ( ( ( ( ( 3 3 2 3 2 6 2 3 . Fe s HNO aq Fe NO aq H g + + At 25ºC and 720 torr, 1.3 L of hydrogen gas are produced. How many moles of iron were in the original iron bar?
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