I've got a chemistry question for anyone who can help me! It's really bugging me and it seems really simple!?

Question

A new grill has a mass of 30.0 kg. You put 2.5 kg of charcoal in the grill. You burn all the charcoal and the grill has a mass of 30.0 kg. What is the mass in kg of the gases given off? (assume that the charcoal is pure carbon solid and that it burns completely in oxygen).

Answer 1

lexi's answer is correct.

the answer above it is not - it tells you the mass of carbon burnt off , true - not the mass of the gas which was created, as the gas is carbon dioxide.

the question wanted the mass of gas given off.

Answer 2

Balanced equation for the complete combustion of C is

C(s) + O2(g) ------> CO2(g)

first you need to work out moles of C present.

Moles of Carbon (charcoal) = mass / molecular weight

molecular weight carbon = 12.01 g/mol

therefore moles of C = 2500 g / 12.01 g/mol

= 200 moles of carbon in 2.5 kg

From the reaction above you see that 1 mole of carbon burns to yield 1 mole of CO2, so the moles of CO2 produced from the combustion of 200 moles of C = 200 also.

Now we can work out the mass of CO2 produced.

mass of 200 moles of CO2

molecular weight CO2 = 12.01 + (16.00 x 2) = 44.01 g/mol

mass = moles / molecular weight

therefore mass = moles x molecular weight

= 200 moles x 44.01 g/mol

= 8802 g of CO2

= 8.8 kg

Answer 3

2.5 kg, carbon as an element keeps the same density and as a gas takes up more volume, allowing the mass to stay the same.

You are basically adding 2.5 kg and removing it, the process is just rapid oxidation but does not change the mass.