How much heat will be evolved in formation of 22 grams of co2 in combustion of formaldehyde?
Answers
What mass of CO2 will be formed when 6g of carbon is burnt in 32g of oxygen?
This question is based on the identification of limiting reagent and finding the mass of CO2 based on its amount. A limiting reagent is one which is present less in amount as compared to which is required. Let's consider an example first.
If you want to make four robots, you'll need 4 heads, 4 torso, 8 hands(4 pair) and 8 legs(4 pair). However, you are given only 3 heads, 4 torso,8 hands and 8 legs. With this condition, you could make only three robots, because of the deficit of heads. Here, head is the limiting reagent.
Let's come to the question. It includes a simple combustion reaction with stoichiometry 1:1.
C + O2 = CO2
According to stoichiometry, 12 g of carbon should react completely with 32g of oxygen to give 44g of CO2. However, we have only 6g carbon, while 32g of oxygen in the question. So, carbon is the limiting reagent.
Now, 12g carbon produces 44g CO2.
Therefore, 6 g carbon produces only 44/12 * 6 g CO2. = 22g CO2.
Another method,
Moles of carbon= (Given wt./molecular wt.)
= 6g/12g = 0.5 moles.
So According to stoichiometry,
1 mole carbon reacts to give 1 mole CO2
And 0.5 mole carbon reacts to give 0.5 mole CO2,
Which is again 22g of CO2.