Question

help with the following concentration question

8. In one study the concentration of OH in air at the time was found to be 8.7x106 molecules per cubic centimeter. Calculate the molar concentration, and its concentration in parts per trillion, if the total air pressure is 1.0 atm and the temperature is 15°C

Answer 1

Answer:

Given,

To determine the molar concentration and its concentration in parts per trillion

Now consider,

n = 8.7*10^6 / 6.022*10^23

= 1.44 * 10^-17 moles

molarity = n/0.001

= 1.44*10^-17 / 0.001

= 1.44* 10^-14 Molar

let us consider,

PV = NRT

substitute the known values in the above formula

N = 1 * 0.001 / 0.082*(273 +15)

N = 4.234 * 10^-5

ppt of OH = 1.44*10^-14 * 10^12 / 4.234*10^-5

ppt of OH = 340