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Chem Practical


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ratio of mass per unit volume
intensive property
property that doesn\'t change when you take away some the sample
any material made up of 2 or more substances that are not chemically combined
empirical formula
the simplest whole no. ratio of atoms in a compound
Law of Constant Composition
any pure chemical compound that is made up of 2 or more elements in the same proportion by mass
container w/ insulated walls that prevents rapid heat exchange btwn the walls and its surroundings
specific heat
intensive physical property, is the quantity of heat in cal necessary to raise the temp of 1 g of substance by 1 C
Law of Dulong & Petit
atoms of all simple bodies have exactly the same capacity for heat, mass of water x specific heat of H2O x change in temp of water/ mass of the substance x change in temp of atoms = specific heat
Conservation of Energy
energy is being neither created nor distroyed, only changed from one form to another and the total amount of energy is constant in a closed system
heat is released by the reaction -change in heat
heat is absorbed by the reation +change in heat
Charles Law
when the pressure is held constant, the volume of a fixed mass of ideal gas is in direct proportion to the temp in Kelvin
effective collision
a molecule collision that results in a reaction
activation energy
minimum energy necessary for the reaction to happen
substance that increases the rate of reaction w/o itself being used up in the process
addad a base to an acid until all the acid is neutralized
end point
when a sudden change in the pH occurs, meaning titration is done
back titration
adding excess base to an acid and then adding acid until the excess base is neutralized, counting how much acid was added will tell how much base was neutralized by acid in the 1st reaction
linear measurement
SI Unit: meter use: meterstick
SI Unit: kilogram metric use balance
SI Unit: m^3 metric unit: liters
SI Unit: joule metric unit: calorie
rate of reaction
How does temperature affect density?
When a liquid or a gas is heated, the molecules move faster and move apart, reducing density. The opposite happens during cooling.
Techinques used to separate a mixture:(5)
sublimation, extraction, decantation, filtration, evaporation
involves heating a solid until it passes directly from solid phase into gaseous phase
uses a solvent to selectively dissolve 1 or more components from a solid mixture
this separates a liquid from an insoluble solid sediment by carefully pouring the liquid from the solid w/o disturbing the solid
this separates a solid from a liquid through the use of a porous material like a filter
process of heating a mixture in order to drive off a volatile liquid
Rates of reaction are dependent on what 5 variables? How does their change affect the rate of reaction?
1)nature of reactants- some compunds are more reactive than others 2)concentration- in most reactions, the rate increases when the concentration of either or both reactants is increased 3)surface area- an increase in the surface area of a solid will increase the rate of reaction 4)temperature- increasing the temp makes the reactants more energetc every time the temp increases by 10 C, the reaction rate doubles 5) catalyst- any substance that increases the reaction rate w/o being used up
formula for equilibrium constant
K=[products] [reactants] where the [] indicate mols/L at equilibrium
Calculate % recovery in an experiment:
weight of recovered solids/weight of initial mixture
Calculate: % error
actual value-calculated value actual value
empirical formula of an oxide:
weight of metal/ g/mol: weight of oxygen/ g/mol
Empirical formula of a hydrate:
mols H2O/ moles of anhydrous salt= 1: ration of H2O
calculate volume of water drawn into a flask (v/t=v/t)
boilng point of water= T2 room temp= T1 volume of flask= V2, V2-V1= volume of water
Difference btwn accuracy and percision:
accuracy-how good your device is at getting a true measurement percision-how reproducible the measurement is

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