Chalk is impure calcium carbonate. the amount of calcium carbonate present can be determined by hydrochloric acid to a sample of chalk and measuring the volume of carbon dioxide produced caco3(aq) + 2hcl -> cacl2(aq) + co2(g) + h2o(g) excess hydrochloric acid was added to 0.5g chalk and 100cm3 of carbon dioxide gas was given produced at r. t.p calculate the percentage purity of calcium carbonate in sample of chalk

Approximately .

Explanation:

How many moles of gas are released?

The volume of each mole of of an ideal gas is approximately under room temperature and pressure (r.t.p, , .) That's the same as .

Assume that acts like an ideal gas.

.

is in excess. How many moles of formula units will produce that of ?

Consider the ratio between the coefficient of and that of .

.

In other words,

.

What's the mass of that many ?

Relative atomic mass data from a modern periodic table:

Formula mass of :

.

Mass of that of :

.

Percentage mass of in this sample of chalk:

.

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.

hurricanes form in warm water