whats the empirical formula

[dentalstudent2021]

if 4.58% H , 40.9% C and 54.52% O is given

Molecular Mass is 264 g /ml


KBB does it a certain way but they don't round their calculations but do exact calculations which seems a tall task w/o a calc.

---

Members don't see this ad.

 

[RuffDay]

This is how I would do it.
First we know that oxygen takes about half of the weight of the total mass. I would round the Oxygen to 50%, but remember since we are under estimating, then we should round to a higher whole number.

50% of the molecular mass is 132g and divide that by the oxygen mass (16g) would be 8.25. Since we are underestimating, we round the oxygen to the higher whole number, 9.

With 120g left after subtracting the molecular weight of oxygen. We have about 80% of carbon. This is also an underestimate, so we have to round the whole number up or increase it by 1. 120g x .8 is about 96, then divide by 12g = 8 carbons. Since this is an underestimate, we want it to be a 9.

We now have C9O9 and the rest would be hydrogen. I am guessing it is C9H12O9.

The DAT won't be this hard.

 

[BeaverLover]

Did ADA list empirical formulas as being possible subject on DAT? Don't remember Chad going over it

 

[RuffDay]

Did ADA list empirical formulas as being possible subject on DAT? Don't remember Chad going over it

I would say expect it. It is actually probably one of the easiest questions you will encounter on the DAT. I had a question that involves finding the empirical formula when I took the DAT.