calculate the number of moles of nitrogen gas present in 400cm3 sample of it a pressure of 790 mmHg and 27°C.

0.02 mol

Explanation:

Given data:

Number of moles of nitrogen = ?

Volume of sample = 400 cm³

Pressure = 790 mmHg

Temperature = 27°C

Solution:

Volume of sample = 400 cm³ (400/1000=0.4 L)

Pressure = 790 mmHg (790/760 = 1.04 atm)

Temperature = 27°C (27+273=300 K)

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

1.04 atm ×0.4 L = n× 0.0821 atm.L/ mol.K  ×300 K

0.416 atm.L =  n× 24.63 atm.L/ mol

n = 0.416 atm.L /24.63 atm.L/ mol

n = 0.02 mol

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.