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3 years ago

Explain distillation and chromatography

1 answer:

6 0

Distillation is the action of purifying a liquid by a process of heating and cooling.
The definition of chromatography is "a process of separating out different parts of chemical mixtures onto an absorbent material that can then be individually analyzed because different parts are caught on the material at different rates."

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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)

Nutka1998 [239]

Explanation:

1) Mass of carbon dioxide = 100 g

Molar mass of carbon dioxide = 44 g/mol

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

1 mol = 0.001 kmol

2.273 moles= 2.273 × 0.001 kmol = $2.273\times 10^{-3} kmol$

2) 1 liter of ethyl alcohol of density $0.789 g/cm^3$

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

Density of ethyl alcohol =d = $0.789 g/cm^3$

$1 cm^3=1 mL$

Mass of ethyl alcohol = m

$m=d\times V=0.789 g/cm^3\times 1000 mL=789 g$

Molar mass of ethyl alcohol = 46 g/mol

Moles of ethyl alcohol = $\frac{789 g}{46 g/mol}=17.152 mol$

$17.152 mol=17.152\times 0.001 kmol=1.7152\times 10^{-4} kmol$

3) Volume of oxygen gas,V = $1.5 m^3=1500 L$

$1 m^3= 1000 L$

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

Pressure of the gas ,P= 1 atm

Moles of oxygen gas = n

$PV=nRT$

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

0.01632 mol = 0.01632 × 0.001 kmol= $1.632\times 10^{-5} kmol$

4) Volume water in mixture = 1 L

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

Mass of water = $1000 g/L\times 1 L = 1000 g$

Volume of alcohol = 2.5 L

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

Mass of alcohol = $789 g/L\times 2.5 L = 1972.5 g$

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

Mass percentage of water :

$\frac{1000 g}{2972.5 g}\times 100=33.64\%$

Mass percentage of alcohol :

$\frac{1972.5 g}{2972.5 g}\times 100=66.36\%$

Moles of water :

$n_1=\frac{1000 g}{18 g/mol}=55.55 mol$

Moles of alcohol =

$n_2=\frac{1972.5 g}{46 g/mol}=42.88 mol$

Mole fraction of water :

$\chi_1=\frac{n_1}{n_1+n_2}=\frac{55.55 mol}{55.55 mol+42.88 mol}=0.5644$

Mole fraction of alcohol :

$\chi_2=\frac{n_2}{n_1+n_2}=\frac{42.88 mol}{55.55 mol+42.88 mol}=0.4356$

3 0

3 years ago

Which changes occur as a cadmium atom, Cd, becomes a cadmium ion, Cd2+?

koban [17]

The answer is (3). To form the cation (positive ion), Cd must lose negative charge, so two electrons are lost. This loss in electrons also increases the effective nuclear charge/ reduces electron shielding. In other words, with two less electrons to hold, the nucleus exerts a stronger attractive force on the remaining electrons, so the electron cloud is pulled closer to the nucleus. The radius therefore decreases.

3 0

3 years ago

I NEED HELP PLEASE !!!!

babunello [35]

I think the answer is C

7 0

3 years ago

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An alpha particle is an ionized helium nucleus, consisting of 2 protons and 2 neutrons bound together. When alpha particles are

grin007 [14]

Answer:

Due presence of empty as well as heavy particles.

Explanation:

The main reason for this is the presence of empty spaces as well as heavy particles in the nucleus of Helium atom. Most of the beam pass through the helium atom due to the presence of empty spaces in the atom whereas some beams deflect from the helium atom because both repel each other due to same charge i.e. positive charge. Few beams of light bounce back with an angle of 90 degree due hitting with the nucleus where heavy particles such as neutron and proton are present.

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3 years ago

WILL MARK BRAINLIEST!!! The freezing point of a solution will ______ and the boiling point will _______ with a(n)_____ in the am

gladu [14]

The freezing point of a solution will decrease and the boiling point will increase with an increase in the amount of dissolved solute. Solutes affect the boiling point of the solvent because it is the temperature where vapor pressure of the solvent becomes equal to the external atmospheric pressure. Increased amount of solutes will cause the solvent to take more time and temperature to make vapor pressure and causes the boiling point to increase. Increased solutes decreases freezing point by interfering with the frozen solution's crystal structure. Temperatures will have to be colder to overcome it.

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2 years ago