Test 4 – Chemistry Flashcard

Solution
a homogeneous mixture in which one substance called the solute is uniformly dispersed in another substance called the solvent
Hydration

when water molecules surround each ion.


hydration of the ions diminishes their attraction to othe rions and keeps them in solution


Ex:

             H2O

NaCl(s)——->Na+ (aq) + Cl (aq)

Nonpolar solutes
requier nonpolar solvents for a solution to form
“like dissolves like”

way of saying that the polarities of a solute and a solvent must be similar in order to form a solution

 

Solute (polar/ionic) –> Solvent (polar)

Electrolytes
dissolve in water and when they separate into ions forming solutions that are able to conduct electricity
nonelectrolytes
dissolve in water at molecules and can’t conduct electricity
Dissociation

some or all of the solute that dissolves produces ions


in an equation for dissociation of a compound in water , the charges must balance


ex:


Mg(NO3)2(s); H2O;; Mg2+(aq) +2NO3(aq)

strong electrolyte
100 % dissociation of the solute into ions
Weak Electrolyte
compound that dissolves in water mostly as molecules
Equivalent (Eq)
the amount of that ion equal to 1 mole of positive or negative electrical charge
solubility
the amount of a solute tha tcan dissolve ina given amount of solvent
unsaturated solution
when a solute readily dissolves when added to the solven, the solution does not continan the maximum amount of solute
saturated solution
a solution that contains all the solute that can dissolve
supersaturated solution
when a saturated solution is carefully cooled it contains more solute than the solubility allows
Henry’s Law

the solubility of gas in a liquid is directly related to the pressure of that gas above the liquid

 

at higher pressures, there are more gas molecules available to enter and dissolve in the liquid

soluable salts
ionic compounds that dissolve in water
insoluble salts
ionic compounds that remain as solids even in contact with water
Concentration of solution

C = amount of solute

        amount of solution

Mass Percent

describes the mass of the solute in grames for exactly 100g of solution

 

m/m = mass of solute(g)

               mass of solution (g)

Volume percent (v/v)

v/v =  volume of solute  X 100

volume of solution

Mass/volume Percent (m/v)

    grams of solute      X 100%

milliliters of solution                 

Molarity (M)

moles of solute

liters of solution

dilution

a solvent (usually water) is added to a solution which increases the volume.

 

As a result the concentration of the solution decreases

Colliods

the solute particles are large molecules, they are homogeneous mixtures that do not separate or settle out

 

  • have medium-size particles
  • cannot be filtered
  • can be separated by semipermeable membranes
  • fog, whipped cream, milk, cheese, blood plasma, pearls

Suspensions
heterogeneous, nonuniform mixtures that are very different from solutions or colliods the particles of a suspension can often be seen with the naked eye
colligative properties
depend only on the number of solute particles in the solution
osmosis
water molecules move through a semipermeable membrane from teh solution with the lower concentration fo solute into a solution with the higher solute concentration
osmotic pressure
prevents the flow of additional water into the more concntrated solution
reverse osmosis
a pressure greater than the osmotic pressure is applied to a solution
isotonic solutions
exert the same osmotic pressure as body fluids such as blood
hypotonic solution
has a lower solute concentration water flows into the cell by osmosis
hypertonic solution
has a higher solute concentration water goes out of the cell into the hypertonic solution by osmosis
Dialysis

similar to osmosis

a semipermeable membrane (called dialyzing membrane) permits small solute molecules and ions as well as solbent water molecules to pass through, but retains large particles such as colloids

Chapter 8
Acids

substances that produce hydrogen ions(H+) when they dissolve in water

 

are electrolytes

sour taste

turn litmus red

neutralize bases

Naming Acids

Acids with H and a nonmetal are named with the prefix hydro and end with ic acid

Ex: hydrochloric acid

 

acids with H and  a polyatomic ion are named by changing the end of the name of the polyatomic ion afrom ate to ic acid or ite to ous acid

Bases
are ionic compounds that dissociate into a metal ion adn hydroxide ions (OH) when they dissolve in water
Arrhenius bases

produce OH ions in water

taste bitter or chalky

are electrolytes

feel soapy or slippery

neutralize acids

Bronsted-Lowry Acids and Bases

  • acids donate a proton (H+)
  • bases accept a proton (H+)

Ex: in teh reaction of ammonia and water

  • NH3 is the base that accpets H+
  • H2O is the acid that donates H+

Conjugate Acid-base pairs

in any acid-base reaction, there are two conjugate acid-base pairs

  • Each pair is related by the loss and gain of H+
  • One pair occurs in the forward direction
  • one pair occurs in the reverse direction

Buffers

  • resist changes in pH from the addition of acid or base
  • in the body, absorb H3O+ or OH from foods and cellular processes to maintain pH
  • are important in the proper functioning of cells and blood
  • in blood maintain a pH close to 7.4. A change in the pH of the blood affects the uptake of oxygen and cellular processes

Buffer Solution

  • contains a combination of weak acid-base conjugate pairs
  • may contain a weak acid and a salt of its conjugate base
  • typically has equal concentrations of a weak acid and its salt
  • may also contain a weak base and a salt of the conjugate acid

function of the weak acid in a buffer

neutralize a base

 

Ex: the acetate ion produced adds to the available acetate

 

HC2H3O2 +OH →C2H3O2 + H2O

acetic acid             base        acetate ion        water

Function of the Conjugate Base

 

  • function of the acetate ion  C2H3O2- is to neutralize H3O+ from acids
  • the acetic acid produced contributes to the available weak acid

Ex:

C2H3O2  + H3O+ → HC2H3O2 + H2O

 

 

Buffer Action

Buffer action occurs as

  • the weak acid in a buffer neutralizes base
  • the conjugate base in teh buffer neutralizes acid
  • the pH of the solution is maintained

 

Chapter 9

 

 

nuclear radiation

  • is the radiation emitted by an unstable atom
  • takes the form of alpha particles, neutrons, beta particles, positrons, or gamma rays

 

radioactive isotope

 

  • an unstable nucleus
  • emits radiation to become more stable
  • can be one or more of the isotopes of an element

 

Stable Isotopes

 

 

 Magnesium- 2412Mg (Magnesium-12)

Iodine- 12753I (Iodine-127)

Uranium- None

Types of Radiation:

  1. Alpha particle (α)
  2. Beta particle (β)
  3. Positron (β+)
  4. Gamma ray (γ)

  1. (α)- two protons and two neutrons
  2. (β)- is a igh-energy electron
  3. (β+)-a positive electron
  4. (γ)- high-energy radiation released from a nucleus

Alpha Particle

  • Symbol:  α,  42He
  • Change in Nucleus: 2 protons and 2 neutrons are emitted as alpha particles
  • Mass Number: 4
  • Charge: +2

 

Beta Particle

Symbol:                 β, 0-1e

Change:                a neutron changes to proton and

                                  electron is emitted

Mass Number:      0

Charge:                 -1

Positron

Symbol:              β+,  0+1e

Change:             a proton changes to a neutron and

                                emits a positron

 

Mass number:   0

Charge:             +1

Gamma Ray

Symbol:                  γ,   00γ

Change:                  energy is lost to stabilize the nucleus

Mass Number:        0

Charge:                   0

Radiation protection

 

 

  • alpha particles→paper and clothing
  • beta particles→lab coat or gloves
  • gamma particles→a lead shield or thick concrete wall
  • limiting the amount of time spent near a radioactive source
  • increasing the distance from the source

 

Alpha Decay

  • when a radioactive nucleus emits an alpha particle, a new nucleus forms that has
    • a mass number that is decreased by 4
    • an atomic number that is decreased by 2

balancing nuclear equations
the sum of the mass numbers and the sum of the atomic numbers are equal for the nuclei of the reactants and the products
changes in nuclear particles due to radiation

when radiation occurs

  • particles are emitted from the nucleus
  • mass number may change
  • atomic number may change

guide to completing a nuclear equation

  1. write the incomplete nuclear equation
  2. determine the missing mass number
  3. determine the missing atomic number
  4. determine the symbol of the new nucleus
  5. complete the nuclear equation

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