NAME:
BEACH IN A BEAKER
PRELAB
1. What two methods of separation are used in this lab?
2. Describe 3 additional means of physically separating matter.
3. What is the homogeneous mixture in this lab?
4. What term is used to describe the mixture of sand and water?
5. What is the formula for calculating percent recovery?
6. Read the procedure section and complete writing the procedure on your lab sheets.
INTRODUCTION
The concept of matter, its physical and chemical properties and how it can be classified and separated was studied in chapter 1. Pure substance is a classification of matter that included elements and compounds, each with definite composition that can be recognized each time that element or compound is found. Mixtures of pure substances are far more common.
Recall that a mixture is defined as two or more pure substances that are physically mixed together. Mixtures do not have definite proportions (or ratios) or substances and the substances contained retain their original properties. A homogeneous mixture is one where it appears uniform throughout. Kool-Aid would be an everyday example of a homogeneous mixture. A solution of hydrochloric acid would be a laboratory example of a homogeneous mixture. A heterogeneous mixture has distinct regions, or separate phases, that can be discerned with the naked eye or a microscope. Everyday examples of heterogeneous mixtures include concrete and chocolate chip cookies. A laboratory example of a heterogeneous mixture is one of iron (metallic pieces) and sulfur (a powdered yellow solid).
In this lab investigation, substances commonly found on the beach will be mixed and then separated through filtration and evaporation. Other methods of separation, not used in this lab, are discussed in your notes and in chapter 1 in the text.
OBJECTIVES
1. To proficiently separate a mixture of water, salt, and sand using evaporation and filtration with less than 10% error.
2. To write a multi-step lab procedure.
MATERIALS
NAME:
100 ml and 250 ml beakers
stirring rod
china marker
ring stand and ring
filter paper
funnel
water bottle
oven
hot plate
sand
salt
electronic balance
NAME:
PROCEDURE
1. Obtain a piece of filter paper and record its mass in the data table (after it has been folded and the corner removed).
2. Write your initials on the beakers using a china marker. Be prepared to scrub this off later with a test tube brush and soap. Weigh the beakers and write their masses in your data table.
3. Place 1/2 a scoopula full of the salt in your beaker, weigh it, and record the data in your table.
4. Place 1 scoopula full of sand in your beaker, weigh it, and record the data in your table.
Write a stepwise procedure for separating a salt and sand mixture using the materials listed above, the picture of the filtration set up, and the data table to help determine what data should be recorded. This should be completed before you come to lab.
5.
DATA and OBSERVATIONS
Record qualitative data as the lab proceeds. (Write these qualitative observations in your formal lab report in the summary section.)
Numerical value / UnitMass of filter paper
Mass of small beaker
Mass of small beaker and sand
Mass of small beaker salt and sand
Mass of small beaker, filter paper and contents after drying
Mass of large beaker
Mass of large beaker and contents after drying
CALCULATIONS
When preparing this section for your formal lab, include a typed heading to show what you are calculating, then show all work (even subtraction) and units when performing the calculation.
1. What was the mass of sand at the start of the experiment?
2. What was the mass of sand recovered after drying?
3. What is the percent recovery of the sand?
4. What was the mass of the salt at the start of the experiment?
5. What was the mass of salt after drying?
6. What is the percent recovery of the salt?
7. Calculate the percent error of the salt recovery using the following formula:
|mass of salt recovered – mass of salt at the beginning| x 100
mass of salt at the beginning
POST LAB QUESTIONS
Answer the following using complete sentences. Show calculations when necessary.
1. The sand is separated from the liquid by ______.
2. What two physical properties of the sand allow this to occur?
2. The salt cannot be separated by filtration because…
3. Suggest reasons for a percent recovery less than (or greater than) 100% for the salt and sand.
4. How did your percent recovery and percent error value for salt compare to each other. (Specifically, how are they related numerically?)
5. What if iron filings had been added to you beach mixture? Suggest how you could have separated them. When should this separation occur (in relation to the rest of the procedure?)
6. Define filtrate. What was the filtrate in this lab?
7. Suggest a way to separate the water that was used to dissolve the salt from the mixture. What equipment would you need to completely separate the water? Discuss the procedure.
8. When sodium chloride is dissolved in water, write the ions that are present in solution.
9. True/ False The salt and water solution is an electrolyte solution.
10. Environmental alert: There was an oil spill at your beach (in a beaker). Sketch a picture of your beach in a beaker and label the sand, salt water and oil. Suggest a method to remove the oil.