How can I find molecular weights for specific substances?

Can you tell me the molecular weights of KHP and aspirin? totoybato1@hotmail.com

First, you must look up the molecular formula for the compounds. The molecular formula of KHP (potassium hydrogen pthalate) is C₈H₅O₄K, and the molecular formula of aspirin (acetylsalicylic acid) is C₉H₈O₄.

The sum of atomic weights in the formula gives you the compound's molecular weight:

KHP, KC₈H₅O₄ aspirin, C₉H₈O₄

8 carbons 8×12.011 = 96.088 9 carbons 9×12.011 = 108.099

5 hydrogens 5×1.00797 = 5.03985 8 hydrogens 8×1.00797 = 8.06376

4 oxygens 4×15.9994 = 63.9976 4 oxygens 4×15.9994 = 63.9976

1 potassium 1×39.102 = 39.102 sum: 180.160

sum: 204.227

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! How can I find molecular weights for specific substances?

	KHP, KC₈H₅O₄		aspirin, C₉H₈O₄
8 carbons	8×12.011 = 96.088	9 carbons	9×12.011 = 108.099
5 hydrogens	5×1.00797 = 5.03985	8 hydrogens	8×1.00797 = 8.06376
4 oxygens	4×15.9994 = 63.9976	4 oxygens	4×15.9994 = 63.9976
1 potassium	1×39.102 = 39.102	sum:	180.160
sum:	204.227