Test 4 – Chemistry – Flashcards

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)

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)

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)

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

C = amount of solute

        ^{amount of solution}

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

m/m = mass of solute(g)

               ^{mass of solution (g)}

v/v =  volume of solute  X 100

^{volume of solution}

    grams of solute      X 100%

^{milliliters of solution}                 

moles of solute

liters of solution

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

As a result the concentration of the solution decreases

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

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

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

are electrolytes

sour taste

turn litmus red

neutralize bases

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

produce OH^- ions in water

taste bitter or chalky

are electrolytes

feel soapy or slippery

neutralize acids

• 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+

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

• 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

• 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

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 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 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

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

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

 Magnesium- ²⁴₁₂Mg (Magnesium-12)

Iodine- ¹²⁷₅₃I (Iodine-127)

Uranium- None

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

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

Symbol:                 β, ⁰_-1e

Change:                a neutron changes to proton and

                                  electron is emitted

Mass Number:      0

Charge:                 -1

Symbol:              β+,  ⁰₊₁e

Change:             a proton changes to a neutron and

                                emits a positron

Mass number:   0

Charge:             +1

Symbol:                  γ,   ⁰₀γ

Change:                  energy is lost to stabilize the nucleus

Mass Number:        0

Charge:                   0

• 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

• 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

when radiation occurs

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

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