am Vo: Attempt 1 A sample of dintrogen pentoxide is known to contain 1.2x10 mole

Question

am Vo: Attempt 1 A sample of dintrogen pentoxide is known to contain 1.2x10 molecules. What is the mass of this sample, in grams? - Your Answer: Answer Save Question 9 (1 point) What is the percent composition of barium in the compound barium chlorate? Do not include the percent sign in your answer, just the number. Your Answer Answer Save Question 10 (1 point) The molar mass of one empirical unit of the antidepressant rolicyprine (C H&NO;) is 122.1 g/empirical unit. If the molar mass for rolicyprine is approximately 250 g/mol, how many empirical units are present in each molecular unit? 'Y /

Explanation / Answer

there are 6.023*1023 molecules in every moles of any substance, also known as Avagadro number.

1.2*1024 molecules are there in 1.2*1024/ (6.023*1023) moles =1.99

moles= mass/molar mass, molar mass of dintrogen pentoxide is N2O5. atomic weights : N=14, O=16

molar mass =2*14+5*16= 108 g/mole

mass of N2O5= moles* molar mass= 1.99*108 gm =214.92 gm

2, Barium chlorate is Ba(ClO3)2, atomic weights (g/mole); Ba= 137, Cl=35.5 and O= 16

molar mass of Ba(ClO3)2= 137+2*(35.5+3*16)= 304 g/mole

moles= mass/molar mass, basis : 1 mole,

hence for 1 mole, mass =molar mass =304 g/mole

mass of Ba(Clo3)2= 304

mass of Ba= 137

mass% of Ba = 100*137/304 =45.1%

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