What is the empirical formula of a hydrocarbon that contains 89.94% C by mass?
Answer: C3H4
So basically what you would do is you world take the 89.94 and divide that by the mass of carbon (and I am just going to round) and that would be 89.94/12=7.495 (I'll round that to 7.5). Then you would subtract 100-89.94 and you're going to subtract by 100 because we are dealing with percent, and percent is ALWAYS out of 100%. So after subtracting you're going to get 10.06 for hydrogen. The mass for hydrogen is 1, so then you'll divide 10.06/1 and the answer is going to be 10.06.
Example: C= 89.94/12 = 7.495----> 7.5
H= 10.06/1 = 10.06 ----> 10.1
You then take the smallest ANSWER you got out of Carbon and Hydrogen. Which is 7.5 from carbon and divide EACH answer.
Example: C= 89.94/12 = 7.495----> 7.5 7.5/7.5 =1
H= 10.06/1 = 10.06 ----> 10.1 10.1/7.5 =1.34---> round to 1.3
Like what one of the previous people stated. You can only round the answer for the empirical formula if its like 3.9 to 4, 5.01 to 5, 2.1 to 2. So, our answer is 1.3 and we can't round it and you can't leave the answer as a decimal.
Example:
Our answer is going to be from 1.3 to 1 1/3 (a mixed fraction).
To get rid of the mixed fraction you're going to multiply 3 (denominator of fraction) from each side.
Example:
(3)1 1/3(3) now the 3 is going to cross out each other from the denominator and you're going to multiply the 3 to the 1 (WHOLE NUMBER of the fraction)
so then, you'll get 3x1= 3, and since the 3 from the denominator of the fraction cancelled out you're only going to get a 1 from the numerator. After, you'll add the number you multiplied and the numerator together.
Example:
product of the 3x1 =3 and what's left of the fraction a.k.a the numerator =1
3+1=4
Since, now we have a whole number 4 will be the answer for hydrogen. H4!
Now, go back to when we had the mixed fraction
1 1/3 and we had to multiply by 3 on each side.
Remember we had to multiply by 3 to cancel out the denominator
The 3 (a.k.a the multiplier) is now going to be your NEW answer for 3.
So the final answer is:
C3H4
*I hope you could understand everything, I know the notes are long, but its hard to type this instead of writing it. I also hope that everything was actually useful and helpful.
Goodluck!
89.94%C, then
100-89.94 = %H.
Take a 100 g sample which will give you the percent in grams.
Convert grams to moles. moles = g/atomic mass.
Then find the ratio of the elements to each other with 1.00 being the lowest. The easy way to do that is to divide the smaller number by itself (which assures that number of being 1.000), then divide the other number by the same small number and round to whole numbers (but don't round too much. See note:) This is the empirical formula.
Note: If the number is close to q whole number (1.06 2.1 2.9, etc round it. If it is further away, such as 1.24 1.33, etc, multiply by whole numbers until you find values for both that can be rounded to whole numbers. For example, 1.00 and 1.33 could be multiplied by 3 to obtain 3 and 3.99 which can be rounded to 3 and 4.)
C7H10 is not an option.
Oh, I see you're interested in hydrocarbons, huh? Well, let me put on my lab coat and get my clown goggles on! *honk honk*
To find the empirical formula of this hydrocarbon with 89.94% carbon by mass, we need to do some clown chemistry!
First, let's assume we have 100 grams of this hydrocarbon. That means we have 89.94 grams of carbon (because it's 89.94% carbon), and the remaining mass will be hydrogen.
The atomic mass of carbon is roughly 12 grams per mole, while hydrogen is about 1 gram per mole. So, we can start by converting the mass of carbon to moles by dividing by 12, and the mass of hydrogen by dividing by 1.
After calculating the moles of carbon and hydrogen, we can see the ratio between them. And guess what, dear explorer of science?! This ratio will give us the subscripts for the empirical formula!
So, in light of all this clown chemistry, the empirical formula for this hydrocarbon would be... (drumroll)... CHâ‚„! (One carbon, four hydrogen atoms)
Now, go forth and spread the joy of empirical formulas, my friend! *throws confetti*
To determine the empirical formula of a hydrocarbon that contains 89.94% carbon by mass, you need to follow these steps:
Step 1: Convert the percentage of carbon to grams.
The first step is to convert the percentage of carbon to grams. Assuming you have 100 grams of the hydrocarbon, 89.94% of that will be carbon. So, the mass of carbon will be 89.94 grams.
Step 2: Convert the mass of carbon to moles.
To convert the mass of carbon to moles, you need to know the molar mass of carbon. The molar mass of carbon is approximately 12.01 g/mol. Divide the mass of carbon by the molar mass to get the number of moles of carbon.
89.94 g C / 12.01 g/mol = 7.489 mol C
Step 3: Determine the ratio of atoms.
Now you need to determine the ratio of atoms in the empirical formula. Since the hydrocarbon only contains carbon and hydrogen, you can focus on those two elements. Use the mole ratio to determine the number of moles of hydrogen.
Assuming the hydrocarbon contains x moles of hydrogen,
7.489 mol C : x mol H
Step 4: Simplify the ratio.
The empirical formula needs to have whole number ratios. To simplify the ratio, divide both the number of moles of carbon and hydrogen by the smallest number of moles obtained.
In this case, both 7.489 mol C and x mol H can be divided by 7.489 mol (since it is the smallest number).
7.489 mol C / 7.489 mol = 1 mol C
x mol H / 7.489 mol = x/7.489 mol H
So, the simplified ratio is 1 mol C : (x/7.489) mol H, or 1 : (x/7.489).
Therefore, the empirical formula for the hydrocarbon is C1H(x/7.489).
Please note that to obtain the actual empirical formula, you would need to know the number of moles of hydrogen, which is not provided in the given information.