Question

what is the mass 224 ml oxygen at NTP

Answer 1

moles of oxygen = 224/22400

= 0.01

=> mass of oxygen = 0.01×32

= 0.32 g

Answer 2

Avagadro's law states that at 1 mole of  of an ideal gas occupies 22.4 liters of volume. 

-This is a useful concept that we can use to calculate the mass of the oxygen.

⇒Calculation:

22.4 liters = 22.4m³ or 22400 ml

∴ If 22400 ml = 1 mole

then, 224 ml = 1 × 224 ml / 22400 ml

                     = 0.01 moles

We can use this moles of oxygen to calculate the mass of oxygen from the following formula:

mass = moles x molar mass

molar mass of oxygen = 32 and the calculated moles = 0.01

∴ mass = 32 × 0.01 = 0.32 g

The mass of 224 ml oxygen then is 0.32g