How many moles, kmols in: 100 g of CO2, 1 litre of ethyl alcohol of density 0.789 g/cm3 and a) 1.5m3 of O2 at 25°C and 1 atm. b) A mixture of water and ethyl alcohol is made up of 1 litre of water and 2.5 litre of alcohol. Calculate the mass fraction and mol fraction for water and alcohol Density of water 1000 kg/m Density of alcohol 789 kg/m

Respuesta :

Explanation:

1) Mass of carbon dioxide = 100 g

Molar mass of carbon dioxide = 44 g/mol

Moles of carbon dioxide =[tex]\frac{100 g}{44 g/mol}=2.273 moles[/tex]

1 mol = 0.001 kmol

2.273 moles= 2.273 × 0.001 kmol = [tex] 2.273\times 10^{-3} kmol[/tex]

2) 1 liter of ethyl alcohol of density [tex]0.789 g/cm^3[/tex]

Volume of ethyl alcohol ,V= 1 L = 1000 mL

Density of ethyl alcohol =d = [tex]0.789 g/cm^3[/tex]

[tex]1 cm^3=1 mL[/tex]

Mass of ethyl alcohol = m

[tex]m=d\times V=0.789 g/cm^3\times 1000 mL=789 g[/tex]

Molar mass of  ethyl alcohol = 46 g/mol

Moles of ethyl alcohol = [tex]\frac{789 g}{46 g/mol}=17.152 mol[/tex]

[tex]17.152 mol=17.152\times 0.001 kmol=1.7152\times 10^{-4} kmol[/tex]

3) Volume of oxygen gas,V =[tex]1.5 m^3=1500 L[/tex]

[tex]1 m^3= 1000 L[/tex]

Temperature of the gas = T= 25°C = 298.15 K

Pressure of the gas ,P= 1 atm

Moles of oxygen gas = n

[tex]PV=nRT[/tex]

[tex]n=\frac{RT}{PV}=\frac{0.0821 atm L/mol K\times 298.15 K}{1 atm\times 1500 L}=0.01632 mol[/tex]

0.01632 mol = 0.01632 × 0.001 kmol=[tex]1.632\times 10^{-5} kmol[/tex]

4) Volume water in mixture = 1 L

Density of water =  [tex]1000 kg/m^3=\frac{1,000,000 g}{1000 L}=1000 g/L[/tex]

Mass of water = [tex]1000 g/L\times 1 L = 1000 g[/tex]

Volume of alcohol = 2.5 L

Density of alcohol =  [tex]789 kg/m^3=\frac{789000 g}{1000 L}=789 g/L[/tex]

Mass of alcohol = [tex]789 g/L\times 2.5 L = 1972.5 g[/tex]

Mass of mixture = 1000 g + 1972.5 g = 2972.5 g

Mass percentage of water :

[tex]\frac{1000 g}{2972.5 g}\times 100=33.64\%[/tex]

Mass percentage of alcohol :

[tex]\frac{1972.5 g}{2972.5 g}\times 100=66.36\%[/tex]

Moles of water :

[tex]n_1=\frac{1000 g}{18 g/mol}=55.55 mol[/tex]

Moles of alcohol =

[tex]n_2=\frac{1972.5 g}{46 g/mol}=42.88 mol[/tex]

Mole fraction of water :

[tex]\chi_1=\frac{n_1}{n_1+n_2}=\frac{55.55 mol}{55.55 mol+42.88 mol}=0.5644[/tex]

Mole fraction of alcohol :

[tex]\chi_2=\frac{n_2}{n_1+n_2}=\frac{42.88 mol}{55.55 mol+42.88 mol}=0.4356[/tex]