What is the empirical formula for a compound that is 53.3% O and 46.7% Si?

Explanation:

When calculating an empirical formula from percentages, assume you have a 100g sample. This allows you to convert the percentages directly to grams, because X % of 100g is X grams.  

So:

53.3% = 53.3g O, 46.7% = 46.7g Si

The next step is to divide each mass by their molar mass to convert your grams to moles.

53.3g/15.99g = 3.33 mol

46.7g/28.08g = 1.66 mol

Then you will divide all of your mol values by the SMALLEST number of moles. This gives you whole numbers that are the mole ratio (subscripts) of the empirical formula.

3.33 mol/1.66 = 2

1.66 mol/1.66 = 2

So the empirical formula is

1 a

2 d

3 a

4 c

explanation:

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.