chemistry

Lab 9a. Mixtures:

1. Quantitative separation of Mixture (sand and salt):

https://www.youtube.com/watch?v=vjnhNm8rv9E

Watch this video to have a better understanding of this lab.

In this experiment, we will be separating a mixture of sand and salt using differences in the physical properties of these two substances. The difference that will use to our advantage to separate the two substances is their solubility in water: while salt is soluble in water, sand does not dissolve in water.

The goal of this experiment is to determine the mass percent of each component in the mixture (% sand and % salt).

Step 1. Record the mass of an empty beaker (1)

Step 2. Add approximately 5.0 g of mixture (sand + salt) to the beaker. Record the mass (2)

Step 3. Add approximately 15 mL of water to the beaker with the mixture (sand + salt).

Step 4. Record the mass of an empty evaporating dish (3)

Step 5. Decant the water (pour the liquid without disturbing the sediment on the bottom of the container) into the evaporating dish.

Step 6. Add an additional 10 mL of water to the beaker with the mixture and decant this second portion of water into the same evaporating dish.

Step 7. Set the beaker with the sediment on a heating plate to dry. After the beaker is dry (no water droplets around the beaker), record the mass of the beaker containing the sand (4)

Step 8. Set the evaporating dish containing the two portions of salt water on a heating plate and heat to dryness. Record the mass of the evaporating dish and white solid (salt) (5)

Use the data provided by your instructor to complete the following information.

Lab Report Data Provided

1. Mass of empty beaker = ____________

2. Mass of beaker + mixture = ____________

3. Mass of empty evaporating dish = ____________

4. Mass of beaker + sand (after drying) = ____________

5. Mass of evaporating dish + salt (after drying) = ____________

Show work to receive credit for your answers.

1. Mass of mixture =	______________
2. Mass of sand =	______________
3. % sand in mixture = *calculated from the mass of sand in the beaker after drying*	______________
4. Mass of salt =	______________
5. % salt in mixture = *calculated from the mass of salt in the evaporating dish after drying*	______________
6. % salt + % salt =	______________

Note: It is ok if it does not add to 100%, remembering we calculated the percent from the masses of each solid in the beaker.

Factors that cause % sand + % salt to not add to 100%:

· the initial mixture sample could have contained a small amount of water

· a small amount of sample could have been lost in the process

Additional Problems (Show work to receive credit)

7. Is the mixture in this experiment (sand + salt) a homogeneous or heterogeneous mixture?