A5.91 g unknown sample analyzed by elemental analysis revealed a composition of 37.51 % c. in addition, it was determined that the sample contains 1.4830 × 1023 hydrogen atoms and 1.2966 × 1023 oxygen atoms. what is the empirical formula?

Explanation:

1) Calculate the mass of carbon (C)

2) Calculate the number of moles of C

3) Calculate the number of moles of hydrogen atoms, H:

4) Calculate the number of moles of oxygen atoms, O:

5) Find the mole ratios:

Summary of moles:

Divide every amount by the smallest number, which is 0.184:

Multiply by 3 to round to integer numbers:

Multiply by 2 to round to integer numbers:

Use the mole ratios as superscripts to write the empirical formula

Just as a reference, you can search in internet and find that one compound with that empirical formula is citric acid.

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.