oone on sonaul Heata les rez Name printed) gradelo\" 7 or question 8. Clearly cr

Question

oone on sonaul Heata les rez Name printed) gradelo" 7 or question 8. Clearly cross out the question you do not wish to be graded. Calculate the root-mean-square velocity of a gas with a density of 2.24 g/L at a pressure of 1.24 7. rature of 425 K. 8. 1.0000 gram of a mixture containing only solid maghesium chloride and solid barium nitrate is dissolved in water. An excess of sodium sulfate solution is added and 0.1000 grams of a dry precipitate is recovered. What is the percent of magnesium chloride in the original 1.0000 grams sample of the mixture? (Hint: What is the net ionic equation?)

Explanation / Answer

7. molar mass of gas = pRT/P

p = density = 2.24 g/L

P = 1.24 atm

R = gas constant

T = 425 K

so,

molar mass of gas = 2.24 x 0.0821 x 425/1.24 = 63.32 g/mol

root mean square velocity = sq.rt.(3RT/molar mass)

                                          = sq.rt.(3 x 8.314 x 425/63.32 x 10^-3)

                                          = 409.16 m/s

8. Ba2+ + SO4^2- --> BaSO4

mass of BaSO4 = 0.1 g

moles BaSO4 = 0.1 g/233.38 g/mol = 4.3 x 10^-4 moles

mass Ba(NO3)2 present = 4.3 x 10^-4 moles x 261.337 g/mol = 0.112 g

mass MgCl2 present = 1 - 0.112 = 0.888 g

percent MgCl2 = 0.888 g x 100/1 g = 88.80%

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