Organic Chemistry-Empirical formula problems

[ChemistryGuy1]

Homework Statement

1)After analyzing an organic substance ,it came to this: 29,752% Carbon;5,785%Hydrogen:26,446% Sulpur and 11,57% Sodium.It is also that known that between the Oxygen mass and Sodium mass ,in a mole of substance analyzed,it's a difference of 18 grams.Determinate the molecular formula of the substance.

2) Volume of 0,56 dm3 of a gas hydrocarbon weights in normal conditions 1,45 grams.Knowing that the atomic ratio of the elements of the hydrocarbons is C : H = 2 : 5 fiend the molecular formula of the hydrocarbons.
A)CH4 B)C2H6 C)C4H10

3) A probe from a organic substance whit the raw(brute) formula CnH2nO who contains 0,6 moles makes in oxidation 79,2 mini grams CO2.Determinate the molecular formula of the organic substance

How i do these problems?

Homework Equations

It's the first semester and it's using basic formulas plus it will use the empirical formula to fiend the formula at the end i think

The Attempt at a Solution

I don't know how to do it :/ i mean i may know how to begin a little but it may be wrong

Tell me what you don't understand and i shall translate it for you

 

[nate808]

1) To determine the molecular formula of the substance, we need to first calculate the empirical formula. This can be done by converting the percentages of each element into moles. Then, we need to find the lowest whole number ratio of these moles to get the empirical formula. The molecular formula can then be determined by multiplying the empirical formula by a whole number.

2) To determine the molecular formula of the hydrocarbon, we need to first calculate the molar mass of the gas. This can be done by using the ideal gas law and the given information about the volume and weight of the gas. Then, we need to find the ratio of carbon to hydrogen in the hydrocarbon. The molecular formula can then be determined by multiplying the empirical formula by a whole number.

3) To determine the molecular formula of the organic substance, we need to first calculate the molar mass of the substance by using the given information about the number of moles and the amount of CO2 produced. Then, we need to find the lowest whole number ratio of carbon, hydrogen, and oxygen in the substance. The molecular formula can then be determined by multiplying the empirical formula by a whole number.