CHM 121L QUIZ 4 - CHM 1211 Name/‘ Full 201 1 Quiz#4...

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Unformatted text preview: CHM 1211. Name: /‘ Full 201 1 Quiz #4 Potentially useful information: Molar Masses (g/mol): Ba = 137.3 S = 32.07 0 = 16.00 I. (12 pts) To analyzed the percent sulfate in an unknown hydrated metal sulfate (MySO4-XH20), Deug dissolved 0.293 g of the unknown salt in 100 mL deionized water in a 7.50 mL beaker and added 2 mL 6 M HCl. He then put 10 mL of 0.25 M BaClz in a lOOmL beaker and diluted it to 40 mL with deionized water, and heated both solutions to near boiling on Bunsen burners. He then added the B210; solution to the unknown salt solution and continued heating the mixture on a hot plate to coagulate the insoluble salt. He then filtered the solid using a filter paper weighing 0.425 g and let the filter paper and its contents dry for a week. The weight of the dried filter paper solid was 0.556 g. What is the chemical formula of the insoluble salt collected at the end of the experiment? $0 $Q ‘l 1% ii What are the u e -.. of sulfate ions formed? vest—Cw; = @‘h‘ 2% J J". g LEG \g m0\ She 77k . oi r 0 iii. What is the mass of sulfate iii theuunknown hydrate metal sulfate? fig“ WK, / 3 iv. What is the percentage by mass sulfate in the unknown hydrated metal sulfate? U.\'b\ * \OO : \\\\'l o ‘ 0.2%3 2- ‘” 3 2. (1 pts) The unknown salt you are going to use today is a hydrate. What do you need to do to remove the water of hydration? /.g (7 .~/ From you: reading a: the dimnion m oftodly's lab define may the mains ol'the following turns i. Efllorescent salt ii. Deliqucscatt all 4-(2 PU) Whalisthcmnflgodof the two-week cxpcrimeru" To wmmm am mkdou vuum glib”; / 2/ 5139!!) Before putting yourunknown in the cmcibleyware instruaed tohatittowd botandcontimchcatingitformhchmimna Whatisthemainreuoa? {it "bl strum MP; "A “Mint Z, / 6. (8 pu) Which Mariana) from the following list are true (1') or false (F) about today's experiment? *0 4W. (lwlbt i. Always weigh the crucible while it is still hot. E ii. Han the crucible containing the unknown to red hot. l: ‘- <6 iii. Use I clean blue flame when heating the crucible. Y iv. Touch the crucible gently with your finger to check if it is cooled. F ———_ ...
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