Lab Quiz 1 Flashcards
What type of property is density?
Physical
What is accuracy?
How close the measurement is to the accepted value or theoretical value
What is precision?
The repeatability of measurement
How do you find deviation?
The average subtracted from individual measurements
What is a mixture?
Matter containing two or more substances
What is a heterogenous mixture?
All of the elements retain their individual identities
What is centrifugation?
The process of separating a solid or a precipitate from a liquid by whirling the mixture at a very high speed
What is decantation?
The process of separating a liquid from a precipitate or a solid by carefully pouring off the liquid and leaving behind the solid
What is distillation?
The process by which a liquid is brought to its boiling point, vaporized, then condensed and collected
What is extraction?
The process of separating one substance from another because it has a greater solubility in a different solvent
What is filtration?
The process of removing a solid or a precipitate from a liquid by using a porous barrier, membrane, paper filter, etc. to prevent the movement of of the solid or precipitate through the barrier
What is sublimation?
The process whereby a solid changes directly into a gas without a liquid phase being present
How do you find the percent error?
Theoretical minus experimental divided by theoretical times 100
How do you find the empirical formula?
Find the experimental number of moles of each element and divide by the smallest number of moles, multiply by until all are integers (if necessary)
What does “water of hydration” or “water of crystallization” mean?
When water is bonded to a structure of a substance
What are hydrates?
Substances with water bonded to them
What does anhydrous mean?
When a crystal solid does not contain water molecules bonded to its crystalline structure
What does effloresce mean?
The hydrates lose their water of hydration naturally when the water vapor pressure int he air surrounding them drops
What is a desiccant?
Salts that absorb moisture from the air to form hydrates (drying agents)
What is a dessicator?
A glass vessel with a tight closing lid used to keep samples dry
What does deliquescent mean?
Salts that absorb moisture from the atmosphere and create a hydrate or solution
What is a primary standard?
Any highly stable substance whose purity is extremely high
What is a titration?
The use of a burette to quantitatively deliver a known amount of a solution of known concentrate as it reacts with a known amount of a solution of unknown concentration
What is the end point or equivalence point?
When the two reactants are chemically equivalent
Usually when the color of an indicator is retained in a titration
What is an indicator?
An organic dye that changes color when the reaction is complete
What is molarity?
A term used to express the concentration of a solute, expressed as moles per Litre (moles of solute per Litre of solution)
What is the difference between moles and molarity?
Moles represents the amount or quantity of material present, molarity represents the concentration of a solution
What does M mean?
M = mols / L
What is the formula for molarity?
M = moles of solute / Litres of solution
How do weak electrolytes react in water?
The remain in their molecular form
What does aqueous mean?
The substance is water soluble
How do aqueous solutions react in water?
All aqueous substances are ions, so they are soluble in water
What is a molecular equation?
An equation that represents a balanced chemical equation showing the physical states of the reactants and the products
What is an ionic equation?
An equation that represents the balanced equations in ion form
What is a net ionic equation?
An equation that represents the balanced ionic equation excluding the spectator ions
What are spectator ions?
Ions that are the same on both sides of the equation endplay no direct role in the reaction
What are oxidation numbers?
AKA “charge” or “oxidation states,” they represent the number of electrons lost, gained, or shared in bonding
What is the oxidation number for a free element?
0
What is oxidation number for a monatomic ion?
It equals its charge
What is the oxidation number of oxygen?
-2 (except in peroxides)
What is the oxidation number of hydrogen?
1+
What is the oxidation number of Group 1 (IA) elements?
1+
What is the oxidation number of Group 2 (IIA) elements?
2+
What is the sum of oxidation numbers in a compound?
0 (neutral)
What is the sum of oxidation numbers of a polyatomic ion?
Equals its charge
What is oxidation?
The loss of electrons by an element
What is reduction?
The gain of electrons by an element
What is a double replacement reaction?
The combining of two compounds to form two new compounds
What is an oxidizing agent?
The substance that gains electron
What is the reducing agent?
The substance that loses electrons
How do you classify redox reactions?
If the oxidation number on any element has changed, it is classified as a redox reaction.
What is the difference in half-reaction equations in acidic solutions and basic?
In basic solutions, you must neutralize the addition of H+ ions with the same number of OH- to create H2O
