Chemistry

Pepper and soap experiment: what's going on?

HI- My 9 year old son would like to know why a certain science experiment works- when you put pepper in a bowl of water, the pepper floats. When you insert a bar of soap, the pepper is immediately repelled by the soap and moves to the edges of the... Read more →

Why do electrons pair if they repel each other?

Dear Dr. Phaneuf, You are always telling us to keep electrons paired on the Lewis structures we draw. But don't electrons repel? Confused in gen chem I Dear confused, Ah, the mysterious mysteries of nature! You are right to be confused and I applaud your discerning question. Why would electrons... Read more →

calculating molarity: The units tell you what to do

Dear Dr Erskine, I am having some difficulty figuring out number 76, but have understood everything else fairly easily up to that point. Would you mind giving me any pointers on that one? V Hey V, Here's the problem, Calculate the concentrations of each ion in a solution that results... Read more →

Why isn't HF a strong acid?

Dear Dr Phaneuf, Since fluorine is the most electronegative atom, why isn't HF a strong acid, too? The HCl bond should be less polarized than the HF bond. 5110 student Dear 5110 student, You are right, F is more electronegative than Cl, and if the only factor were electronegativity, HF... Read more →

stoichiometry with gases

Subject: Chemistry Lab Question Hi Holly, I have a problem to solve for my chemistry lab and am having a brain fart. We are supposed to determine the atomic mass of an unknown metal. The question reads: A sample of 40.0 mg of a metal reacts with HCl according to... Read more →

Does shaking salad dressing hydrogenate it?

Holly, Our nutrition teacher says that if you shake a mixture of oil and vinegar, as in salad dressing, the oil gets hydrogenated. This sounds unlikely based on what we learned in class. Don't you need hydrogen gas and a metal catalyst? A questioning student Dear questioning, Oh dearie, dear... Read more →

A volatile question

Hey Holly! I think I know why I equate volatility with explosiveness. (am i making up words?) I know explosive gases have to reach a certain ratio as to oxygen to become explosive. So volitility is a measure of how quickly they can disperse in the air? This wouldn't have... Read more →