Chem Lab Exam 1 - Separating The Components Of A Mixture

Front 1

During the lab "separating the components of the mixture" we separate the mixture into its individual components by using differences in _______

Back 1

solubility

Front 2

Solubility is an example of an intensive/extensive physical property that can be measured without changing the composition of a substance

Back 2

Intensive

Front 3

What is defined as the maximum amount of a substance that dissolves in a specific amount of solvent at a particular temperature and pressure?

Back 3

Solubility of a substance in a solvent.

Front 4

Solubility is expressed as?

Back 4

Mass of substance per volume of solvent.

Front 5

For the slab, your objective is to determine the correct percentage of each of the three components in your mixture. Such determinations are known as?

Back 5

Quantitative analysis

Front 6

Analyzing for the precise amounts of substances present a sample is known as quantitative/qualitative analysis?

Back 6

Quantitative analysis

Front 7

Analyzing for the correct identities of substances present and a sample is known as quantitative/qualitative analysis?

Back 7

Qualitative analysis

Front 8

In this lab, you will separate a mixture containing three solid substances. What are these three substances and give their chemical formula

Back 8

Salt, sodium chloride (NaCl); benzoic acid (C6H5COOH); Sand, silicon dioxide (SiO2)

Front 9

You are given a file containing salt, benzoic acid, and sand. Which substance would you attempt to measure first, and how?

Back 9

You would first remove the benzoic acid from the mixture using isopropyl alcohol, which will dissolve benzoic acid, but will not dissolve the sodium chloride or silicon dioxide. Since you're looking to measure how much benzoic acid was in the original sample, you must first weigh the entire sample and evaporatorating dish and record the mass in grams. After a few more additional washes with the isopropyl alcohol, use a hot plate to dry the remaining mixture, allow to cool, and reweigh the evaporating dish to determine the mass of the remaining mixture.

Front 10

How can you be sure that the isopropyl alcohol has removed all of the benzoic acid from the sample?

Back 10

Take a glass stir rod and place a tiny amount on a clean watch glass and allow to evaporate. If the isopropyl alcohol evaporates without leaving a residue, the benzoic acid has been removed from the remaining solids.

Front 11

After you have removed all of the benzoic acid from the sample, which substance will you measure next?

Back 11

Next you'll remove the sodium chloride from the silicon dioxide. Since salt is soluble in water and sand isn't, you will add a little bit of water, stir, and decant each wash into a pre-weighed beaker until all of the sodium chloride has been removed from the wet sand. Test with silver nitrate to ensure no NaCl remains in the sand. Then, taking the preweighed beaker of the NaCl supernectant, use a bunsen burner to evaporate the remaining water. Place a watch glass on top of the beaker to prevent splattering and loss of salt water. Don't forget to dry the watch glass to prevent the condensation from skewing the results. Once completely dry, reweigh and use the differences to calculate the mass of NaCl.

Front 12

How can you be sure that all of the sodium chloride has been removed from the sand?

Back 12

The solution of silver nitrate (AgNO3) Will be provided to test whether the sodium chloride has been removed. Before decanting the last water wash, place a few drops of the wash in one of the watch glasses. Add one drop of silver nitrate. If any chloride is still present it will form a white precipitate.

Front 13

Assume that you were unsuccessful at removing all of the sodium chloride from the sand upon testing the water wash with silver nitrate. Write the chemical reaction that shows the sodium chloride reacting with the silver nitrate to form the white precipitate you see. Then, name the precipitate.

Back 13

NaCl(aq)+AgNO3(aq) --> NaNo3(aq) + AgCl(s). ; AgCl(s) is the precipitate.

Front 14

Now that you have removed the salt from the sand, what should you do with the remainder?

Back 14

The sand will be wet, so be operating dish should be placed on a hot plate and stirred with a stirring rod until the sand is dry. Once cool, reweigh and record the mass.

Front 15

How would you indirectly determine the mass of the sodium chloride? How would you directly determine the mass of the sodium chloride?

Back 15

Mass Evaporating Dish with and Salt & Sand - Mass Evaporating Dish with only dry Sand = Indirect mass of Sodium Chloride........ Mass of preweighed beaker and dry NaCl - Mass of preweighed beaker = Direct mass of Sodium Chloride

Front 16

Recall how we recorded the mass of benzoic acid. Was this a direct or indirect determination?

Back 16

Indirect. Mass of evaporating dish and sample–mass evaporating dish with salt and sand only.

Front 17

How would you directly determine the mass of sodium chloride?

Back 17

Mask of beaker, watch glass, and dry NaCl - Mass of preweighed beaker and watch glass = Direct Mass NaCL