Which observation illustrates the law of conservation of mass?
the c: o mass ratio of a particular compound is the same, regardless of the size or source of the sample.
when 3 g of carbon reacts with 8 g of oxygen, 11 g of carbon dioxide is produced.
the c: o mass ratio of one compound is exactly double that of another compound.
burning 10 g of propane produces twice as much carbon dioxide as burning 5 g of propane.

When 3 g of carbon reacts with 8 g of oxygen, 11 g of carbon dioxide is produced.

Explanation:

According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

Given: mass of carbon = 3 g

mass of oxygen = 8 g

Mass of products = Mass of carbon dioxide = 11 g

Mass or reactant = mass of carbon + mass of oxygen = 3 g  + 8 g = 11g

Thus the total mass of reactants is equal to the total mass of products.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

answerlinnaeus;