How many moles (of molecules or formula units) are in each sample? Part A 42.37 g CF2Cl2 Express your answer to four significant figures.

0.3504 mol of CF₂Cl₂.

Explanation:

We need to know the molar mass of CF₂Cl₂ to find out the moles

Molar mass of C = 12 g/mol

Molar mass of F = 19 g/mol

Molar mass of Cl = 35.45 g/mol

Molar mass of CF₂Cl₂ = 12 + 19 . 2 + 35.45 . 2 =120.9 g/mol

Now we determine the moles of our mass

42.37 g . 1 mol / 120.9 g = 0.3504 mol

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.

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