Potassium hydrogen phthalate is often used to standardize solutions of strong bases. Highly pure samples of this solid weak acid are readily available. It is stable and easy to use in the laboratory. Calculate the molarity of a sodium hydroxide solution if 23.73 mL are required to titrate 0.5816 g of potassium hydrogen phthalate (C8H5O4K).

0.12 M

Explanation:

Molarity of sodium hydroxide = number of moles of sodium hydroxide / volume in liters

equation of reaction between NaOH and Potassium hydrogen phthalate

NaOH(aq) + KHC₈H₄O₄(aq)  KNaC₈H₄O₄(aq) + H₂O(aq)

molar mass of KHC₈H₄O₄ = 204.22g/mol

amount required to titrate with NaOH = 0.5816 g

mole of  KHC₈H₄O₄ = 0.5816 g / 204.22g/mol = 0.00285 mole

considering the equation, 1 mole of NaOH required 1 mole of KHC₈H₄O₄

0.00285 mole  KHC₈H₄O₄ will require 0.00285 mole of NaOH

Molarity = 0.00285 mole  / ( 23.73 ml / 1000ml) L = 0.12 M

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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