Chapter 3 Matter Properties and Changes. DENSITY. Density is a ratio that compares an objects mass to its volume. The unit for density is g/ L or g/ cm 3 .
Chapter 3 Matter Properties and Changes
Mass of reactants = Mass of products
A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When the reaction was complete, the student obtained 39,7 g of sodium chloride. How many grams of chlorine gas reacted? How many grams of sodium reacted?
In any chemical reaction or physical process, energy can be converted from one form to another, but it is neither created nor destroyed.
A mixture is a combination of substances physically combined. Physical separation methods take advantage of known physical properties of individual components of a mixture.
Filtration uses a solid barrier to separate heterogeneous mixtures of a a solid and a liquid (sand & water).
Distillation uses differences in boiling points to separate a homogeneous mixture.
Crystallization separates a mixture and forms a solid that is pure. Like making rock candy.
Chromatography separates components of a mixture on the basis of the tendency of each to travel or be drawn across the surface of another material.
Elements have a unique name and chemical symbol. The symbol consists of one, two or three letters. The first letter is always capitalized and any following letters are lowercase.
Percent by mass
% mass = mass of element x 100 mass of compound