Chemistry Lab Report

Chemistry Lab Report

Student’s Name

University

Instructor

Date

Chemistry Lab Report

Introduction

In this lab report, the aim is to discuss about the density of the mystery liquid and solid. Density of any given substance can easily be obtained provided that there are masses and volumes given because Density is given by mass divide volume (D=M/V). Density is measured using grams per cubic cm (g/cm3). Depending on the density of a substance, it can float on liquids provided that their density is less. Therefore, this report explains some of the procedures used to measure masses and volumes, observation, discussion, and conclusion.

Safety

Before the start of the experiment, safety needs to be observed because most substances provided in the laboratory are poisonous and some are corrosive. To avoid dangers, I labeled all the reagents on the bench and the substances to be used during the experiment. The mystery solid and liquid were labeled and I used gloves to avoid touching them directly. I also covered my nose and face to avoid inhaling the substances directly and avoid any spill as it can be corrosive to my skin.

Procedure

The first part of the report required that I make a claim about the identity of the substance and to ascertain that, I had to measure the density of the liquid to have an overview of the possible identity of the liquid. For accuracy, three trials each done different was conducted and average value obtained to use the averaged value that is more accurate in making inference of the substance.

Trial Density (g/cm3)

1 0.733

2 0.759

3 0.775

Average density = (0.733+0.759+0.775)/3

= 0.754g/ml

Since the density of alcohol is 0.758g/ml, the inferences that I made was that the claim of the mystery liquid is alcohol.

Part B of the question required me to make a claim of the identity of the mystery solid. Achieving this requires comprehensive measures of the solid in about three trials and getting the average density to make a claim of the probable solid. The table below was filled before calculating the average density.

Trial Density (g/cm3)

1 8,88

2 9.01

3 9.12

The average density = (8.88+9.01+9.12)/3

= 9.01g/cm3

With the margin error of about 0.05, the density ranges within the accepted density of copper which is usually 8.89g/cm3.

Many ways can be used when identifying liquids and one way is through the use of their densities. First, it was observed that the mystery liquid was clear. Obtaining the density of the liquid requires various steps that include getting the mass of the liquid and volume to determine the density. After measuring the mass of the liquid in the first step, the second step involved getting the mass of the flask used where I used three trials to confirm the accuracy.

Trial Mass (g)

1 42.66

2 42.41

3 42.43

Step three involved calculating the volume of the mystery liquid and three trials were done too as shown.

Trial Volume (ml)

1 2.85

2 4.90

3 9.29

Step 4 involved mass of the flask and the mystery liquid

Trial Mass (g)

1 44.75

2 47.85

3 49.83

Step 5 involved calculating the mass of the mystery liquid and it involved getting the differences of step 4 and step 2 to have (44.75-42.66) = 2.09g, (47.85-42.41) =5.24g, and (49.83-42.43) = 7.2g

Using the formular D=M/V

The average density of the liquid would be 0.756g/ml and it is proposed to be alcohol as per my calculations.

In part B, similar procedures as in A were done and to get the volume of the solid, volume displacement method was used. Mass of the solid was first considered

Trial Mass

1 57.70

2 57.68

3 57.46

Step 3 involved finding the initial volume of water before displacing with the mass of the solid

Trial Initial volume (ml)

1 21.0

2 23.6

3 24.7

Step 4 was finding the volume after displacement by the mass and the results obtained were as follow.

Trial Final volume (ml)

1 27.5

2 30.0

3 33.0

Step 5 involves getting the differences of step 3 and 4 to get 4.5ml, 4.4ml, and 4.3ml

Step 6 involves density of the mystery solid using the formula of D=M/V

That gives average density of 9.01g/ml and it is predicted that the density is of copper metal and the method used to obtain is by volume displacement.

Discussions

Just like when one measures density of solids, getting density of liquids requires one to have mass and volumes of the liquid. Mass is obtained by measuring the empty graduated flask and recording the mass of the flask then add specific volume of the liquid before measuring the mass of flask+ the liquid. Getting the difference between step one and two enables one to get the mass of the liquid. For accuracy purpose, three trials can be done and getting the average is encouraged. Getting the density is the done using the formula Density = Mass/Volume.

Similarly, the mass of the solid can be measured using weighing machine and for accuracy purpose, three trials need to be conducted. The averaged results are obtained before using volume displacement method to determine the volume of water the solid displaces. Using eureka can and a graduated flask is the best strategy because it ensures accurate volume is collected. Alternatively, measuring cylinder can be used where one records initial volume and final to get the volume of the solid based on the differences.

One condition that enables accurate results is that the solid to be measured need not to float in water because it means its density is less than 1g/ml of water and any solid with less than density of 1 float on water. The claimed solid above had a density of 9.01g/cm3 that is higher than water. Also, the other feature of the solid used need not to absorb water because false results will be recorded and the claim will be obviously wrong. Therefore, the solid in the discussion above met all these conditions and it an indication that the results obtained must be correct.

Conclusion

From the experiment, it is possible to calculate the density of the mystery solid by first getting the volume using displacement method and also the mass using the weigh balance. Density is calculated by dividing the mass by the volume and it was achievable. Sometimes, getting into the laboratory requires one to handle apparatus and substances provided with care because some are poisonous and therefore, using gloves and wearing other protective gears is always advised. From the observations made and drawn from the experiment, I claimed that the solid is copper based on the density obtained and the liquid was alcohol. Density is best in identifying substances because different substances can have same masses or volumes but densities are unique because 2 substances cannot have same volume and masses to give similar density.

0 replies