Question

What is the empirical formula for a compound that is 83.7 % carbon and 16.3 % hydrogen?

Answer 1

To find the empirical formula, convert the percentages of carbon and hydrogen to moles. Divide the moles by the smallest mole value to obtain the simplest whole-number ratio. Write the empirical formula using the ratio obtained.

Step-by-step explanation:

To determine the empirical formula of a compound with given percentages of carbon and hydrogen, we need to convert the percentages to moles. First, assume that we have 100g of the compound. Then, we'll calculate the moles of carbon and hydrogen using their molar masses. Next, we'll divide the moles of each element by the smallest mole value to get the simplest whole-number ratio. Finally, we'll write the empirical formula using the ratio obtained.

In this case, assuming 100g of the compound, we have 83.7g of carbon and 16.3g of hydrogen. The molar mass of carbon is 12.01 g/mol and the molar mass of hydrogen is 1.01 g/mol. Calculating the moles, we have 83.7g / 12.01 g/mol = 6.969 moles of carbon and 16.3g / 1.01 g/mol = 16.138 moles of hydrogen. Dividing by the smallest mole value (6.969), we get a ratio of approximately 1 carbon to 2.32 hydrogen. Rounding to the nearest whole number, the empirical formula is CH2.

Answer 2

Step-by-step explanation:

First, you need to be sure the elemental analysis has identified all the components.

83.7+16.3=100% so we’re good, and the same ratio works for the formula,

The formula is CxHy, so x*12+y*1= 100% of the empirical formula wt, which we’ll use later to confirm the elemental analysis. We need x and y

Then x = 83.7/12 is 6.975 and being savvy, we guess it’s supposed to be 7, since empirical formulas use whole numbers if they can. Likewise y=16.3/1 = 16.3, and now we round down to the nearest whole number (16), making our empirical formula C7H16

Check:

7*12+16*1=100 (the empirical formula wt) 84/100=0.84 and 16/100=0.16 This is close enough, so C7H16 is the empirical formula.