Project 1: Inorganic Containments Present in Water Samples

Introduction

Background:

 Chemistry is commonly used when it comes to testing in a laboratory. Scientist use many different ways to determine what an unknown substance is. Looking at the qualitative properties of the substance such as the color, smell and other properties that can be observed and not measured is one way. However, looking at the quantitative properties, measurable portion of testing like moles or melting point, also contribute to the identification process of finding out what an unknown substance is. When looking at substances that are hazardous to wildlife we can use the method of Spectroscopy which is when light interacts with an unknown substance (1). This is an example of a qualitative test because you observed the difference that one substances has with certain types of light. When the police seize unknown substances from criminals or in drug raids they need someone to confirm the identity of these substances. Unknown powders, liquids and even pills that could be potentially illegal would be confirmed by forensic labs. There are two types of test they usually use which are presumptive tests and confirmatory tests. However, unlike presumptive tests, confirmatory tests are very specific and allow the forensic lab to determine the exact identity of the substance (2).

Theory:

 There are four tests that will make up the qualitative procedures of this experiment. These include solubility, conductivity, pH, and a flame test. The unknown compound we had was white in color and had a baking flour appearance meaning that it was fine. These will all be used to help weed out the other unknown substances from a few that would be able to give you a general direction. Solubility tests are generally used to see how soluble the substance is in deionized water. The conductivity test is used to measure the dialysis fluids, according to PubMed.com a dialysis fluid is a solution of salts that are dissociated (3), total concentration of salts. The next test is pH and which measures the pH level of the solution that we made and this helps us narrow down if the substance is an acid base or neutral which will further narrow our choices. A flame test shows us the color of a substance by putting it directly into the flame and each substance has a different color that will appear. Next will be the test that will be the two quantitative procedures of the experiment. Gravimetric analysis is based on weight where Volumetric analysis is based on volume. Volumetric was the one we used since discovering that the unknown we had basic or acidic properties.

Hypothesis:

 Since the portions of our experiment gave us an assumption that after all the test that our unknown substance is Magnesium sulfate (MgSO₄) since it did not have the signature smell.

Objective:

 Week one our goal were to get an idea of what our unknown substance was after all the qualitative experiments. After week one we had a general thought of which of the two substances it would be between. However, week two the goal was to figure out which quantitative experiment worked for us the best and that ended up being the volumetric. Then to proceeded to figure out our substance.

Methods

Part I Methods:

We began the experiment with the solubility test and we started by putting 0.5g of the unknown substance and then 49.5g of deionized (D1) water into a beaker then decided that it was soluble in water. We repeated this same measurements of 0.5g of the unknown substance with 49.5g acetone and ethanol in a beaker but both resulted in the substance being clumpy and could not dissolve into a solution making it insoluble. This helped us minimize options for what the unknown substance could be. Next we made a solution with D1 water and the substance to test the conductivity and pH, we used 70 mL of water with 0.5g of the substance to make our base solution and we conducted the experiment by using the conductivity meter and the pH meter. Using only one at a time, we would turn it on,  stick it into the solution, and waited until it gave us an answer. This showed the conductivity helped determine the conductivity of the substance and the pH helped determine if the acid base or neutrality of the substance. The flame test shows if the substance has a reaction to the flame which will result in the flame changing colors. We used a wire loop to get a little bit of the solution with the substance and then placed it in front of the flame.

Part II Methods:

Finally we gathered the information collected from previous experiments and we decided to conduct the volumetric analysis. We used a solution of .5g of the substance with 70mL water so that it was fully dissolved. Then we added 10 drops of Silver nitrate l into a beaker to get the mixture that we would let drop into our solution.

Safety:

Results

Section I:

CONDUCTIVITY AND pH (AVERAGE of 3 Trials):

FLAME TEST: