What is the mole fraction of oxygen in a gaseous mixture containing 25 grams of oxygen, 15 grams of nitrogen, and 10 grams of helium?

Freezing and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.

Marcel just purchased 1.69 grams of iron fillings in order to make living putty for his 6 year old niece. how many moles of iron are made in his sample?

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?