Please help me A sample of a liquid with mass of 8.657g was decomposed into its elements and gave 5.217 g of carbon ,0.9620 g of hydrogen, and 2.478g of oxygen. What is the percentage composition of this compound

The percent composition of a compound is the calculated measure of each ... A sample of a liquid with a mass of 8.657 grams was discovered into its elements ad gave 5.217 grams of carbon, 0.9620 grams of hydrogen, and 2.478 grams of oxygen. ... mass of oxygen = 2.478 grams ... 14.01 g/mol x100 = 3.03 g/mol x 100.

Hope this helps, please let me know If I'm wrong.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.