Chemistry, 18.09.2019 08:00 davionb556

What is the mole fraction of ethanol when 10.00 ml of pure ethanol is combined with 2.00 ml of water? the volume of 10 ml of the solution must be measured?

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The mole fraction is calculated using the formula:

mole fraction of component A = # of moles of component A / # of total moles of the solution.

A) number of moles of ethanol

To calculate the number of moles of ethanol, you need its density, which will permit you to determine the mass of the 10.00 ml, and then convert into moles using the molar mass of ethanol.

The normal density of ethanol is 0.789 g/ml

density = mass / volume => mass = density * volume = 0.789 g/ml * 10.00 ml = 7.890 g

Molar mass of ethanol = 46.07 g/mol

number of moles = mass / molar mass = 7.890g / 46.07 g/mol = 0.1713 mol

B) number of moles of water

density of water = 1.00 g/mol

mass of water = density * volume = 1.00 g/mol * 2.00 ml = 2.00 g

number of moles of water = mass / molar mass = 2.00 g / 18.0 g/mol = 0.111 mol

C) mole fraction

mole fraction of ethanol = number of moles of ethanol / number of moles of solution

number of moles of ethanol = 0.1713 / (0.1713 + 0.111) = 0.1713 / 0.2824 = 0.607

0.607

The volume of the final solution may be calculated by adding the volume of the two components. This is 10.00 ml of ethanol + 2.00 ml of water makes 12.00 ml of solution.

It is not clear what the second question is meant for. Some context is missing. If you know density and you know maqss (or can calculate the mass from other data) you do not need to measure the volume.

Answer from: cpcoolestkid4

The mole fraction of ethanol in the solution is 0.599.

Moles of solute : Ethanol :

Density = $\rm \dfrac{mass}{volume}$

density of ethanol = 0.789 g/ml

mass of Ethanol = Density $\times$ Volume

mass of Ethanol =0.789 $\times$ 10

mass of Ethanol = 7.89 grams

$\rm Moles\;of\;Ethanol\;=\;\dfrac{weight}{molecular\;weight}$

$\rm Moles\;of\;Ethanol\;=\;\dfrac{7.89}{46.07}$

Moles of Ethanol = 0.16 moles

Density of water = 0.97 g/ml

Mass of Water = 0.97 $\times$ 2 g

Mass of Water = 1.94 grams.

$\rm Moles\;of\;Water\;=\;\dfrac{1.94}{18.0153}$

Moles of water = 0.107 moles

Total moles of solution = Moles of Ethanol + moles of water

Total moles of solution = 0.16 + 0.107

Total moles of solution = 0.267 moles.

Mole fraction of ethanol :

= $\rm \dfrac{0.16}{0.267}$

= 0.599 .

The mole fraction of ethanol in the solution is 0.599.

For more information about mole fraction, refer to the link:

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Answer from: Quest

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.