1) how many atoms of N are there in 30.0g of NH4NO3? 2) The density of CCL4 (l)

Question

1) how many atoms of N are there in 30.0g of NH4NO3? 2) The density of CCL4 (l) is 1.59g/mL. How many molecules areCCl4 are there in 2.50 L of CCl4? 3) If 1.35 L of diborane gas has a mass of 1.67 g at STP, whatis the molar mass of diborane? 4) If 250.0 ML of silane gas at STP has a mass of 0.358g whatis the molar mass of silane? If silane is made of silicon andhydrogen atoms suggest a molecular formula for silane 1) how many atoms of N are there in 30.0g of NH4NO3? 2) The density of CCL4 (l) is 1.59g/mL. How many molecules areCCl4 are there in 2.50 L of CCl4? 3) If 1.35 L of diborane gas has a mass of 1.67 g at STP, whatis the molar mass of diborane? 4) If 250.0 ML of silane gas at STP has a mass of 0.358g whatis the molar mass of silane? If silane is made of silicon andhydrogen atoms suggest a molecular formula for silane

Explanation / Answer

1) Molar mass of NH4NO3 = 80gm/mol => No. of moles = mass/molar mass = 30/80 moles = 0.375moles => No. of atoms = 2 x 6.023 x 1023 x 0.375= 4.52 x 1023 atoms 2) Mass of given CCl4 = density x volume = 1.59 x2500 gms = 3975 gms => No. of moles = 3975/154 moles = 25.8 moles => No. of molecules = 6.023 x 1023 x 25.8 moles= 1.55 x 1025 molecules 3) 1 mole of borane gas at STP has volume = 22.414L => No. of moles of gas = 1.35/22.414 = 0.06 moles => Molar mass of borane = mass/no. of moles =1.67/0.06 = 27.83 gms/mol 4) 1 mole of silane gas at STP has volume = 22.414 L => No. of moles of silane gas = 0.25/22.414 = 0.011moles => Molar mass of silane = mass/no. of moles = 0.358/0.011= 32.1 gms/mol Molar mass of Si = 28 gms/mol => No. of H atoms = (32-28)/1 = 4 atoms Therefore, formula of silane = SiH4 => No. of moles of silane gas = 0.25/22.414 = 0.011moles => Molar mass of silane = mass/no. of moles = 0.358/0.011= 32.1 gms/mol Molar mass of Si = 28 gms/mol => No. of H atoms = (32-28)/1 = 4 atoms Therefore, formula of silane = SiH4

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