MasteringChemistry: Chapter 4-Part 2 . Google Chrome Secure l https://session.ma

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MasteringChemistry: Chapter 4-Part 2 . Google Chrome Secure l https://session.masteringchemistry.com/myct/itemview.assig Chapter 4-Part2Item 9 ID=91 1 671 39&offset;= next Resourcas You completed this assignment. previous | 9 of 28 | next » Item 9 Part A A mixture of NaCl and NaBr has a mass of 2.03 g and is found to contain 0.72 g of Na What is the mass of NaBr in the mixture? Express your answer using two significant figures. mNaBr= 0.46 Submit My Answers Give Up All attempts used; correct answer displayed Continue O Type here to search 12:57 AM 10/19/2017

Explanation / Answer

Molar mass NaCl = 58.44g/mol
Molar mass NaBr = 102.9g/mol
Molar mass Na = 23g/mol

Let the mass of NaCl be X g then mass of NaBr = ( 2.03-X) g
Mass of Na in NaCl : = 23/58.44*X = 0.3936X g
Mass Na in NaBr = 23/102.9 *( 2.03-X) = 0.2235( 2.03-X) = 0.4537 - 0.2235X

We know that total Na+ = 0.72g
0.3936X + 0.4537 - 0.2235X = 0.72
0.3936X -0.2235X = 0.71 - 0.4537
0.1701X = 0.2663
X = 0.2663/0.1710 = 1.5655 g

X is mass of NaCl = 1.5655g NaCl
Mass of NaBr = 2.03-1.5655= 0.4645g NaBr.

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