A 6g sample of carbon allowed to burn in 20g of oxygen gas produce carbon dioxide. After the reaction, the mass of unreacted oxygen is 4 g. What mass of carbon dioxide was produced? show with steps

Approximately .

Explanation:

Look up the relative atomic mass data of carbon and oxygen on a modern periodic table:

Calculate the formula mass of and :

.

.

The question suggests that of took part in this reaction. Calculate the number of moles of molecules in that of :

.

Since is in excess, it would react with at a one-to-one ratio to produce :

.

Notice the ratio between the coefficient of and : . For each mole of that is consumed, one mole of will be produced.

The question implies that , which is approximately , of was consumed in this reaction. Accordingly, of will be produced.

Calculate the mass of that of :

.

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