10/4/22 - Mass Laws and Dalton's Postulates Flashcards
What is the Law of Conservation of Mass?
In a chemical reaction, the total mass of the substances doesn’t change.
Mass not created or destroyed
What is the Law of Definite Composition?
A particular compound is always made of the same elements in the same mass ratio.
What is the Law of Multiple Proportions?
If the elements A and B form two compounds, then A exists in a fixed mass and the mass of B varies, but their masses exist in fixed ratios.
What is a mass fraction?
The mass of an element in a compound divided by the mass of the compound.
What is a mass percent?
Mass fraction x 100
If there are 8.0 g of Ca in 20 g of CaCO3, what is the mass fraction of Ca?
8.0/20 or 0.4
If the mass fraction of Ca is 0.4, what is its mass percent?
0.4 x 100 or 40%
How do you find an element’s mass using a compound’s mass and the mass fraction?
Element mass = (compound mass) x (mass fraction)
What do Dalton’s postulates say about the composition of matter?
Matter is made of indivisible atoms that can’t be created or destroyed.
What do Dalton’s postulates say about converting matter from one element to another?
You can’t convert from one element to another.
What do Dalton’s postulates say about the properties of elements?
An element’s atoms have the same mass and properties, which are unique to that element.
What do Dalton’s postulates say about the formation of compounds?
Compounds result from the combination of specific ratios of atoms of elements.
How do physical properties vary between pure substances and mixtures?
The physical properties of a pure substance are precise and constant, but for mixtures, they vary.
