Example Problem #1

A compound was analyzed and found to contain 13.5 g Ca, 10.8 g O, and 0.675 g H.  What is the empirical formula of the

compound?

Start with the number of grams of each element, given in the problem.

Convert the mass of each element to moles using the molar mass from the periodic table.

Divide each mole value by the smallest number of moles calculated.  Round to the nearest

whole number.

This is the mole ratio of the elements and is represented by subscripts in the empirical

formula.

Mwhahahaha >:DD

You stupid creatures, are you ready? Are you

scared? C’mon, back off first! I know all of you are

scared…. >:D

W-we-were n-not scared…. I know we can do it….. You ugly lich! …. We can defeat you soon…We can answer those stupid questions of yours….We already studied about that…Right Jake? We^___^….

Y-yeah, I guess? Ahmmn, Finn we need

a help… I guess?Ahhhhhhhhh….! Goshh, guys we need your help quick….we need

you’re scientific skills…..We can’t do it alone…..Yahhhhhhhh…..Pretty please guys? Could you? I guess

you said yes…that’s great…..whooooooo….

Then if you’re ready finn and jake…Answer this following questions and determine the empirical formula…..If you answer all the questions perfectly…I will back off but if you didn’t answer my questions perfectly then we need to fight…..Wahahahahahahah >:DDD

U-uh-oowhh…Guys, we really need your help…please ! Pretty

please :”(( I wanna save my Princess Bubblegum….

Answer Keys:

1. 2.

3.

4. 5.

1. 51.28 percent C, 9.40 percent H, 27.35 percent O, 11.97 percent N, MW=2342. 33.18 percent C, 4.60 percent H, 29.49 percent O, 32.72 percent Cl, MW=108.53. 45.71 percent C, 10.48 percent H, 30.48 percent O, 13.3 percent N, MW=2104. 40.00 percent C, 6.67 percent H, 53.33 percent O, MW=330

5. A 10g sample of a compound contains 4.00g C, 0.667g H, and 5.33g O. Find the empirical and molecular formulas. The MW is 180 amu.

Find the empirical and molecular formulas for the compounds given below. Atomic weights: C=12 H=1 O=16 N=14 Cl=35.5

ANSWER THIS PERFECTLY…AND I WILL PROMISE THAT I WILL BRING BACK THE CANDY KINGDOM AND YOUR PRINCESS BUBBLEGUM, FINN….MWAHAHAHHA :D

Answer Keys:1. 2.

3.. 4.

5.

Hey, you promised us that you will bring back the Candy Kingdom and Princess Bubblegum…

Okey, here………

*KAPOWWW*

Ouch, owwh…my head spins like a hell…err? Where am i?

Anybody here? Wahhhhhhhh… I’m alone :”(((

You alright my highness? I’m happy that you’re alive…I will

die if you’ll going to be out of my life…

I’m alright my dear finn, I owe you my life….Thank you for

saving me….

The end…Thanks for your help guys…