QUIZ 3Key

# QUIZ 3Key - ox Aliquet.300 L 1.34 g = 3.23 g L 2 moles KMaO...

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25 Points NAME____ ANSWER KEY_ ________________LAB SECTION#___________________ MOLAR MASS G/MOLE C = 12.01 Fe = 55.85 NH 4 = 18.04 Na = 23.0 O = 16.00 C 2 O 4 2- = 88.02 H 2 O = 18.02 Mn = 54.9 H = 1.008 K = 39.10 SO 4 2- = 96.06 1. (4 pts) Calculate the percent oxygen in K 3 Fe(C 2 O 4 ) 3 (H 2 O) 3. 12 240 X 100 = 48.8% +3 491.3 15 oxygen 16.00 x 15 = 240 2. (4 pts) A student weighed out 122.5 g of potassium permanganate and added it to a 250.0 mL volumetric flask and diluted it to the mark. Calculate the molarity of the potassium permanganate solution. 122.5 g 1 mole KMnO 4 = 3.10 M 158 g 0.250 L (OVER) CHEMISTRY 113 – Fall 2003 LAB QUIZ #3

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3. (8 pts) A solution of potassium permanganate is thought to be 0.0301 M and you are asked to prepare 3.00 X 10 2 mL solution of which 30.0 mL aliquots will be used to standardize the potassium permanganate. If approximately 32.0 mL is to be used, calculate how much Na 2 C 2 O 4 should be weighed out. 5Na 2 C 2 O 4 + 2 KMnO 4 + 8H 2 SO 4 10CO 2 + 2MnSO 4 + 2K 2 SO 4 + 5Na 2 SO 4 + 8H 2 O 0.320 L 0.0301 moles 5 moles
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Unformatted text preview: ox Aliquet .300 L 1.34 g = 3.23 g L 2 moles KMaO 4 .030L 1 mole ox 4. (10 pts) A student weighed out 0.418 g of K 3 Fe(C 2 O 4 ) 3 (H 2 O) 3 (F.W. = 491.3 g/mole) and it took 34.58 mL of a 0.0302 M potassium permanganate solution to reach the endpoint. Zinc dust was added and the solution heated and it took 6.09 mL of the potassium permanganate to reach the endpoint. Calculate the percent Iron and Oxalate in the sample. 5Fe(C 2 O 4 ) 3 3-+ 6MnO4 4-+ 48H + 5Fe 3+ + 30CO 2 + 6Mn 2+ + 4H 2 O 4H + + 5Fe 2+ + MnO 4-5Fe 3+ + Mn 2+ + 4 H 2 0.0302 moles .03458 L 5 moles ox 88.02 g 100 = 55.0% L 2 moles KMnO 4 1 mole C 2 O 4 2-.418g 0.0302 moles .00609 L 5 moles Fe 55.45 g 100 = 12.2% L 1 mole KMnO 4 1 mole Fe .418 g 5. (4 pts) Why did you add ethanol in the synthesis of the potassium trioxalatoferrate? The ethanol reduces the solubility of the potassium trioxaatoferrate (OVER)...
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QUIZ 3Key - ox Aliquet.300 L 1.34 g = 3.23 g L 2 moles KMaO...

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