1.  List the solute and solvent in a glass of lemonade. 

            Solutes-lemon, sugar
            Solvent-water

2.  If 35 grams of a certain salt will dissolve in 100 grams of water at a 25°C.  If you dissolve 30 grams in 100 grams of water at that temp, describe this solution using the words saturated/unsaturated/supersaturated and concentrated/dilute.

            It would be unsaturated and concentrated.  That is quite a bit to dissolve.

3.  a.  Will oxygen gas be more soluble in water at 10°C or 50°C?
     b.  Will ethyl alcohol (drinking alcohol) be more soluble in water at 10°C or 50°C?

            Temperature doesn’t effect solubility of liquids in each other

     c.  Will sugar be more soluble in water at 10°C or 50°C?

4. Which of the following will dissolve in liquid CCl₄?  Why? (both are non-polar as is CCl_4.  Remember “likes dissolves likes”.)

      a.  NH₃                       b.  CS₂                               c.  H₂O                        d.  CF₄

5. When a salt dissolves in water, water molecules surround it.  Which end of the water is attracted to the cation and which to the anion?  What do we call this?

Cations (+) are attracted to the oxygen end of water since that is more electronegative whereas anions (-) are attracted to the hydrogen end since that is more electropositive.  We call this hydration.

6.  Complete these concentration problems:

      a.  What is the Molarity (M) if .0030 moles of KCl is dissolved in water to make 250
            ml of solution?  .0030 moles/.250 liter = .012 M

      b.  What is the Molarity (M)  if 8.5 grams of NaNO₃ is dissolved in water to make
            500 ml of solution?  8.5/85=.1 mole of NaNO3 and .1/.5 = .20 M

      c.  How many grams of CaSO₄ would you need to make 2 liters of 1.0 M solution?
                        g= 136 g/mole x 1 M x 2 liters=272 grams

 7.  Compare a solution of 1 M NaCl to pure water in terms of

     a.  boiling point    NaCl solution is higher
     b. freezing point   NaCl solution is lower
     c. vapor pressure  NaCl solution is lower
     d.  osmotic pressure NaCl solution is higher

8.  Which of these solutions will have the greatest effect on the boiling point?

     a.  1 M CaCl₂        b.  1 M NaNO₃           c.  1 M C₆H₁₂O₆         d.  1M AlCl₃

Note: compare the number of particles or ions a=3, b=2, c=1 (sugar dissolves as a whole particle, not as ions) d=4

 9.  What type of equation is each of the following?

     a.  Cu + AgNO3 ®  CuNO3 + Ag   (Single replacement)
     b.  Cu + S ®  CuS          (Combination or composition)
     c.   2C₂H₂ + 5O₂ ® 4CO₂  + 2H₂O  (Combustion of a Hydrocarbon)
     d.  2NaI + ZnCl₂  ®  ZnI₂  + 2NaCl  (Double replacement)
     e.  2NaClO₃ ®  2NaCl + 3O₂  (Decomposition)

10.  List oxidation numbers for each element in the following:

       a.  H₂                    0         
       b.  CuCl₂              Cu is +2 and Cl is -1
       c.  KMnO₄            K is +1, Mn +7 and O is -2
       d.  HBrO₃             H is +1, Br is +5 and O is –2

  11.  Using the equations in questions #9, list what is oxidized and reduced.

            a.  Copper is oxidized and Ag⁺¹ in AgNO₃ is reduced
            b.  Cupper is oxidized and sulfur is reduced
            c.  Carbon in C₂H₂  is oxidized (goes from –1 to +4) and oxygen reduced
            d.  Nothing. Double replacements are not redox reactions
            e.  Oxygen is oxidized (-2 in sodium chlorate and 0 in pure oxygen) and Cl
                  is reduced (goes from +5 in sodium chlorate to –1 in sodium chloride)

   12.  For each equation, explain if it is exo or endo-thermic.

            a.  2KClO₃ + E ®  2KCl + 3O₂      Endothermic-energy required
            b.  C + O₂  ®  CO₂ + E                     Exothermic-energy released

            Then sketch a graph showing how the energy changes over the time of the 
            reaction.

(I can’t sketch the graph on the computer, but for letter a the reactants are lower energy than the products and for letter b the reactants are higher energy than the products. )

13.  Explain the term Activation Energy.  Activation energy is the energy needed to get a reaction started.  It is needed for both exo and endo thermic reactions.  If there is not enough activation energy, the collision theory says the reaction will not be complete.

14.   If you want to speed up the decomposition of hydrogen peroxide into water and oxygen, list two things you could do to the solution.  You could heat it or add a catalyst.

15.  You have an aquarium divided into two parts with a barrier in between and you put and put 10 goldfish on one side.  Then you remove the barrier.  At what point will equilibrium be reached?  Explain how this is like a chemical reaction.

Initially all the fish are on one side.  Equilibrium is reached when the number of fish on either side is constant.  Meaning for every fish that swims right there is one swimming left.  So the same fish don’t necessarily stay on one side.  Equilibrium is like this, it is dynamic, meaning there is change of reactants to products and vs. versa, but there is no more net change.  (Of course an aquarium is not a perfect example because as Eric says, nature always has this little wobble or imperfection in it and for some odd reason sometime all the fish may be on one side).

Be careful though, and understand that equilibrium doesn’t necessarily mean there are equal amounts of reactants and products.  If K is large you have mostly products and if K is small you have mostly reactants.  The equilibrium just means that you have no net change.  For example if the aquarium was in equilibrium it could be with 3 fish on one side and 7 on the other (maybe there were more interesting things for the fish on the right side).  As long as that didn’t change it would be considered equilibrium, meaning if one swam right another swam left.

16.  Set up the K_eq expression for these equations:

            a.  2C₂H₂ (g) + 5O₂ (g) =  4CO₂ (g)  + 2H₂O (g)   K =(CO₂)⁴(H₂O)²/( C₂H₂)²(O₂)⁵
            b. 4 P(s)+ 5O₂ (g₎ = 2P₂O₅  (g)       K= (P₂O₅)²/(O₂)⁵  ₍Leave out solids and pure liquids)

(Note usually they use square brackets but I don’t know how to do those on computer)

17.  Given the equation  3O₂ (g)  = 2O₃ (g)

       If at a particular temperature at equilibrium the O₂ concentration is .40 M and the O₃
       is  .0030 M, what is the value of K?

            K=(O₃)²/(O₂)³   =  (.003)² / (.4)³  =.00014 or 1.4 x 10^-4

18.   Given the equation in 16a, which way will the equilibrium shift if you

            a.  Add more oxygen     shift forward
            b.  Increase the temperature (assume it is exothermic)  shift reverse
            c.  Cool the temperature   shift forward
            d.  Increase the pressure  shift forward  (note fewer gas molecules on right)
            e.  Add more carbon dioxide  shift reverse

Remeber-shifting forward means you are getting more of the products and shifting reverse means you are getting more of the reactants.

19.   According to Arrhenius, label the following as an acid, base or salt

            a.  CaSO₄                Salt
            b.  HNO₂                   Acid
            b.  NH₄OH                Base

 20.   a.  A liquid tastes sour and turns litmus paper red.  What is it an acid or base?
          b.  A liquid tastes bitter and feels slippery.  What is it an acid or base?

21.  Complete the following ionization equations.  Label the acid and base on either side of the equation

            a.  HF + H₂O ®   H₃O⁺    +       F^-1
                 acid   base     conj. acid        conj. base                       

            b.  SO₄^-2 + H₂O ®  HSO₄^-1     +     OH^-1
                 base     acid           conj. acid      conj. base  

22.  Fill in the table:           

23.  What do we call things like HCO₃^-1  that can act like either acids or bases? amphoteric

 24.  Which of the following is a diprotic acid?

            HNO₃              HC₂H₃O₂                    H₂CO₃

25.  Given the K_a for these two weak acids

            Nitrous acid   HNO₂   is 4.5 x 10 ^–4
            Boric acid H₃BO₃ is 5.8 x 10 ^–10

           a.  Which is a stronger acid?  Nitrous (Note larger K_a)
           b.  Which is a stronger base NO₂^-1 or H₃BO₃^-1  ?  Note that the weaker acid
                has the stronger conjugate base.

            c.  What could you mix if you wanted a buffer approximately equal to 4?

Mix nitrous acid with its conjugate base NO₂^-1 .  In other words mix HNO₂ with a salt like NaNO₂   (NaNO₂ is a source of the ion NO₂^-1)

Boric acid and its borate salt would work as a buffer, but it’s pH would be around 10.

d.  What would the buffer do?  It keeps the pH stable if small amounts of either acid or base are added.

26.  Write the ionization equation for HNO₂ and its K_a expression.

            HNO₂ ®  H⁺ + NO₂^-1
                        or
            HNO₂ + H₂O ®  H₃O⁺ + NO₂^-1     K_a=( H₃O⁺)( NO₂^-1)/( HNO₂)               

27.  Name an acid that will ionize completely.  A strong acid like HCl or HNO_3.  For H₂SO₄ the first H⁺ ionizes completely and the second only partially because HSO4^-is weak.

28.  a.  Which is more acidic a solution with pH 3 or 6? 
       b.  Which is more basic, a solution with pH 10 or 13?      
       c.  If you have a solution with pH of 3 and you start adding water, what will happen
            to the pH?  It will increase or get larger.
       d.  If you have a solution of pH 9 and you add water, what is the lowest pH number
            you will reach?  7.  As you dilute an acid or base it goes to 7 and stops,
            because that is the pH of water.

29.  What is the pH of each of the following:

            a.  .001 M HCl                       pH=3
            b.  .000001 M HCl                pH=6
            c.  .1 M NaOH                       pH=13 (remember if a base to subtract from 14)
            d.  .0001 M NaOH                pH= 10

Good luck.  I didn’t put anything on the pH of salts on my quiz because I didn’t go over it.  If you can do all this you are doing great!!! 

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