Post Lab Questions 1

Post Lab Questions

1. Classify each of the following as a pure substance or a mixture; if it is a mixture, state

whether it is heterogenous or homogeneous: a) concrete, b) tomato juice, c) marble, d)

seawater, and e) iron.

2. How do decantation and filtration differ? Which should be faster?

3. If the mixture of NaCl, NH4Cl, and SiO2 (sand) was first extracted with water and then

both the extract and insoluble residue were heated to dryness, could you determine the

amounts of NaCl, NH4Cl, and SiO2 (sand) originally present? Why or Why not?

4. A mixture was found to contain 3.10 g of SiO2, 0.38 g of cellulose, and 6.72g of calcium

carbonate. What is the percentage of CaCO3 in this mixture?

5. A KBr-AgCl-NiCO3 mixture weighs 3.27 g. After separating the individual components, we

recover 1.32 g KBr, 1.24 g AgCl, and 0.62 g NiCO3. Calculate the total percent recovery of

the mixture.

6. Use the table below to answer the following questions.

a. Could you separate the components of a mixture of Mg(OH)2 and Zn(OH)2 by only

using 3 M HCl? Explain your answer.

b. Could a mixture of benzoic acid and Mg(OH)2 be separated by using 3 M NaOH? Can

it be separated another way instead of using 3 M NaOH? Explain your answer.

c. Briefly describe the procedural steps (step 1, step 2, etc.) you would take to separate

the components of a mixture of benzoic acid, and Zn(OH)2 and recover both

substances.