Download Exam Chemistry of the Environment Review

Solutions Review
1.
You need to prepare a salt water solution for an experiment. You need 500 mL of a 0.60 mol/L
solution of sodium chloride (NaCl).
a) What mass of sodium chloride should be measured out to make this solution?
b)
Explain the steps you should take to make this solution.
c)
You decide you want 100 mL of a weaker solution of 0.20 mol/L of NaCl. What volume of the
original stock solution you just prepared should you use for this dilution?
Acid / Base Review
An unknown sample of sulfuric acid (H2SO4) is titrated with 1.5 mol/L sodium hydroxide (NaOH). For
each titration, 15 mL of acid was placed in the flask. The average volume of base required for the
titration was 106 mL. Find the concentration of the acid.
Organic Review
Prefixes indicating # of carbon atoms:
Meth- Eth- Prop- But- Pent- Hex- HeptFamily Name
Alkanes
Alkenes
Alkynes
Alcohols
Aldehydes
General Formula
C-C single bonds
C=C double bonds
C=C triple bonds
R-OH
O
H
C
R1
C
O
R2
R
C
OH
Ketones
Carboxylic Acids
O
R
Oct- Non- DecName Ending
Notes
# indicates position of double bond
# indicates position of triple bond
# indicates position of hydroxyl
group
Carbonyl group always at END of
chain (no #)
Carbonyl group in MIDDLE of chain # indicates position
Carboxyl group always at END of
chain (no #)
Practice Questions
1. What is the percent concentration (% w/v) of sugar if 39 g of sugar is dissolved in a 115mL solution of
sugar water?
2. Calculate the molar concentration of sodium chloride (NaCl) if 150 g is dissolved in 5.0 L of water.
3. Calculate the mass of silver nitrate (AgNO3) that is required to prepare 2.5 L of a 0.150 mol/L
solution.
4. You need 500 mL of 3.0 mol/L sodium hydroxide (NaOH) for an experiment.
a. How many grams of sodium hydroxide should you weigh out?
b. Describe how you would make your solution. Include the pieces of equipment that you would
use.
c. One step in your experiment requires you to dilute your stock solution down to a concentration
of 0.450 mol/L. You will need 150 mL of this weaker solution. What volume of your stock
solution will you need to make your new solution?
d. Describe how you will do the dilution. Include the pieces of equipment you will use.
5. Convert between pH and [H+].
[H+] = 10-3 pH = _____________
pH = 8
[H+] = ________________
6. 10mL samples of hydrochloric acid are titrated with a standardized 0.2 mol/L solution of sodium
hydroxide. The average amount of sodium hydroxide needed for the titrations was 13.05 mL. Find the
concentration of the hydrochloric acid. The balanced chemical reaction is given below to get you
started:
HCl + NaOH  NaCl + H2O
7. Practice naming and drawing organic compounds. Redo your organic chemistry test, especially questions
1 and 2.
Answers:
1.
% w/v = 33.9 %
2. 0.51 mol/L
3. 63.7 g Ag
4. a) 60 g
4b) Mass out 60 g of NaOH in a beaker and dissolve in a min amount of deionized water. Transfer, wish washings to a
500 mL volumetric flask. Top to the mark with deionized water, cap and shake. 4c) 22.5 mL (use cdvd = ccvc)
4d) Pipette 22.5 mL of 3.0 mol/L stock solution. Add to a 150 mL volumetricflask and top up to the mark with
deionized water. Cap and shake. 5. pH = 3
[H+] =1.0 x 10-8 mol/L
6. Concentration is 0.261 mol/L.