Question

How many molecules of carbon monoxide are in 10 mL at STP

Answer 1

 The number  of  carbon monoxide that  are in 10 ml at STP  is 2.68 x 10²⁰  molecules

 calculation

Step 1 :  convert 10 ml to L

convert 10 ml to L = 10/1000 =0.01 L

Step 2: find the moles of CO at STP

That is at STP  1  mole  = 22.4 L

                           ?moles = 0.01 L

by cross  multiplication

= {0.01 L x 1 mole)/22.4 L} =4.46 x 10⁻⁴  moles

Step 3 ; find the  number of   molecules of Co  using the Avogadro's law constant

that  according to Avogadro's  law  1  moles = 6.02 x 10²³

                                                  4.46 x 10⁻⁴ moles =? molecules

by cross multiplication

= {(4.46 x 10⁻⁴  moles) x( 6.02 x 10²³  molecules) / 1 mole}  =2.68 x 10²⁰  molecules