Chem - Ch 2 Flashcards
extensive property
a property that depends on the amount of matter in a sample
intensive property
a property that depends on the type of matter in a sample, not on the amount of matter
(pure) substance
matter that has a uniform and definite composition
either an element or a compound
What’s a good ‘test’ to see if something is a substance
if you’d reach your hand in, you’d get the same stuff every time
physical property
a quality or condition of a substance that can be observed or measured without changing the substance’s composition
solid
a form of matter that has a definite shape and volume
how are the individual particles arranged in a solid
packed closely together in a rigid arrangement
how are the individual particles arranged in a liquid
close together, but they are free to flow past each other
how are the individual particles arranged in a liquid
particles are relatively far apart and can move freely
liquid
a form of matter that flows, has a fixed volume, and an indefinite shape
gas
a form of matter that takes the shape and volume of its container; has no definite shape of volume
physical change
a change in which the appearance changes, but the composition does not
chemical change
a change in which there is a composition change
examples of physical change
melting, boiling, breaking, cutting, dissolving, state changes
is there any kind of chemical reaction taking place in a physical change
no
are physical changes often reversible or irreversible
reversible
signs of chemical change
produces bubbles, turns cloudy, temperature change, color change, change in smell or taste,
examples of chemical change
baking cookies, nail/penny rusting, fireflies glowing, burning gas, fire
Why do all samples of a given substance have the same intensive properties?
because a substance has a definite composition so the matter in each sample will be the same. Intensive properties depend on the type of matter, and not on the amount of it.
Describe a reversible physical change
something can be done to get it back the way it was before
Describe an irreversible change
nothing can be done to get it back the way it was before
How are liquids and gasses alike?
they both take the shape of their container
How are liquids and solids different?
a solid has a definite shape, a liquid has an indefinite shape
list the 3 states of matter in order of density
solid, liquid, gas
mixture
2 or more substances physically combined
not pure
heterogeneous mixture
not uniform in composition
components are not evenly distributed throughout the mixture
examples of heterogenous mixture
ice cubes in liquid water
mashed, unpeeled potatoes
salad
sand
homogenous mixture
uniform in composition
components are evenly distributed and not easily distinguished
examples of homogenous mixture
green ink
mouthwash
salt water
air
how can you tell what kind of a mixture it is
do spoon test - if you took 2 spoonfuls of the same mixture and if it looks like the same thing in each spoon, then its homo. if not, then its hetero
solution
a homogenous mixture
filtration
a process that separates a solid from the liquid in a heterogeneous mixture
distillation
a process used to separate components of a mixture using differences in boiling points
how is distillation accomplished
by boiling a liquid to produce a vapor. This vapor is then channeled into a condenser that has a cooling coil around it. This turns the vapor back into a liquid. The solid substances that were dissolved in the liquid remain in where they were because their boiling points were higher
how are a substance and a solution similar
they both have a uniform composition
how are a substance and a solution different
a substance is pure (an element or a compound) but a solution is not pure and is always a mixture of two or more things
What are some ways to separate a mixture
distillation, filtration, evaporation, use a magnet, diff melting temps, pick apart by hand, dissolving, extracting based on solubility, diff densities
element
simplest form of matter with a unique set of properties
cannot be broken down into simpler substances by chemical means
compound
a substance that contains two or more elements chemically combined in a fixed proportion
How is a compound different from an element?
An element is the simplest form of matter that has a unique set of properties, while a compound is a substance that contains 2 or more elements chemically combined. Compounds can be broken down into simpler substances by chemical means, but elements can’t.
table salt - compound, element, or mixture? why?
compound because it is made of two elements chemically combined
salt water - compound, element, or mixture? why?
mixture because it is made of two compounds
sodium - compound, element, or mixture?
element bc it is not combined with any other element
what does H20 tell you about the composition of water
the compound water contains two parts hydrogen to one part oxygen
chemical property
the ability of a substance to undergo a specific chemical change
chemical reaction
a change in which one or more reactants change into one or more products
reactant
a substance present at the start of a reaction
product
a substance produced in a chemical reaction
law of conservation of mass
in any physical change or chemical reaction, mass is conserved; mass can neither be created nor destroyed
name 4 possible clues that a chem change has taken place
transfer of energy
a change in color
the production of a gas
the formation of a precipitate
In a chemical reaction, how does the mass of the reactants compare to the mass of the products?
In any chemical reaction, the mass of the products is always equal to the mass of the reactants because of the law of conservation of mass
water boils - physical or chemical change? clue?
physical
charcoal burns in a grill - physical or chemical change? clue?
chemical (color change)
bread dough rises when yeast is added - physical or chemical change? clue?
chemical (production of a gas)
brittle - chemical or physical property?
physical
melts at 140 degrees - chemical or physical property?
physical
What is it called when a solid changes to a liquid
Melting
What is it called when a solid changes to a liquid
Melting
What is it called when a liquid changes to a gas
Boiling
Vaporizing
Evaporating
What is it called when a solid goes directly to a gas
Sublimining
What is it called when a gas goes directly to a solid
Depositing
What is it called when a gas changes to a liquid
Condensing
What is it called when a liquid changes to a solid
Solidifying
Freezing
