Chemistry help 3 problems please complete them all if you can very important and

Question

Chemistry help 3 problems please complete them all if you can very important and got them wrong a few times already thank you so much.

1)A gas mixture is made by combining 6.9 g each of Ar, Ne, and an unknown diatomic gas. At STP, the mixture occupies a volume of 16.36 L.
What is the molar mass of the unknown gas?
_____g/mol
Identify the unknown gas.
is it O2 , N2 , F2, Cl2 or H2

Print Bea Calculator l Periodic Table uestion 21 of 30 Ma a Sapling Learning macmillan A 3.80-g sample of solid BaCl2. 2H20 was heated such that the water turned to steam and was driven off. Assuming ideal behavior, what volume would that steam occupy at 1.000 atm and 100.0 oC? Number

Explanation / Answer

1.

1 mole of any gas at STP occupies 22.4 L

Hence 22.4 L are there in 1 mole of any gas

16.36 L are there in 16.36/22.4 moles of gas. Hence moles of gas mixture = 0.73

Moles of Argon in the samples = 6.9/(molar mass of Argon)= 6.9/40 = 0.1725, moles of Ne= 6.9/20= 0.345

Moles of gas mixture = moles of Ar+ moles of Ne+ moles of third component.

Moles of third component= 0.73-0.1725-0.345 =0.2125 mole

Molar mass of unknown diatomic gas = 6.9/0.2125 =32. The gas is O2.

2.

Molar mass of BaCl2= 208 and molar mass of water = 18

Molar mass of BaCl2.2H2O= 208+36= 244 g/mole

Moles of BaCl2.2H2O in 3.8 gm = 3.8/244 =0.0156

BaCl2.2H2O -------à BaCl2 +2H2O

1 mole of BaCl2 upon heating gives 2 moles of water

0.0156 moles of BaCl2 when heated gives 2*0.0156 = 0.0312 moles of water.

Hence n= 0.0312, T= 100+273=373K, P= 1atm. R=0.0821L.atm/mole.K

From gas law PV= nRT, V= nRT/P= 0.0312*0.0821*373/1 L=0.699 L

3.

From the combustion reaction. 2C8H18+25O2--à16CO2 +18H2O

2 moles of C8H18 gives 16 moles of CO2

522 moles gives 522*16/2 = 522*8= 4176 moles of CO2

Hence n= 4176, T= 14+273= 287 K, T= 0.995, P= 0.995 atm , R= 0.0821L.atm/mole.K

V= nRT/P= 4176*0.0821* 287/0.995=98892 L

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