Question

if 27 g of carbon is mixed with 88 g of oxygen and is allowed to burn to produce co2 then a) oxygen is limiting regent b) volume of co2 gas produced at ntp is 50.4 L c) c and o combine in mass ratio 3:8 d) volume of unreacted o2 at stp is 11.2L​

Answer 1

answer : (b) , (d)

explanation : reaction between carbon and oxygen is .... $C+O_2\rightarrow CO_2$

here we see that one mole of Carbon reacts with one mole of oxygen to form one mole of carbon dioxide.

we know, atomic mass of C = 12 g/mol

molar mass of O2 = 32g/mol

and mar mass of CO2 = 44g/mol

so, we can also say that 12g of carbon reacts with 32g of oxygen to form 44g of carbon dioxide.

or, 27g of carbon reacts with (32/12) × 27 = 72g but oxygen is given 88g (excess amount of oxygen).

so, Carbon is limiting reagent.

now, one mole of C forms one mole of CO2

or, 12g of C form 44g of CO2.

or, 27g of C form 44/12 × 27 = 99g of CO2.

so, number of mole of CO2 = 99g/44g/mol = 9/4

volume of CO2 = 22.4 × 9/4 = 50.4L

hence, volume of CO2 gas produced at NTP is 50.4L

also mass of unreacted O2 = 88g - 72g = 16g

then, number of mole of oxygen unreacted = 16g/32g/mol = 0.5mol

hence, volume of unreacted oxygen = 22.4 × 0.5 = 11.2L