right5779Prince Muhammad Bin Fahad UniversityChemistry Lab (CHEM 1411) Instructor: Lina Alzayer

Section: 218

Chemistry Lab Report 1

Student Name: Badriah Albash Signature: ________________________

Student Name: Maryam AljameaSignature: ________________________

Student Name: Nawal AlsomaliSignature: ________________________

Student Name: Sarah AlsayariSignature: ________________________

Student’s First Name

Aim Waad Ahmed

Introduction Waad Ahmed

Method Maryam Aljamea

Results Badriah Albash

Discussion Sarah Alsayari ; Nawal Alsomali

Conclusion Maryam Aljamea

Student Name: Waad AhmedSignature: ________________________

By signing this sheet:

You agree that you participated in writing the part that is mentioned beside your name in the table on the right

You agree that you revised and tried to edit the other parts that are written by other members in the group in the group

Title: Determination of Density (0.5 mark)

Aim(2 mark)

Determination of density of solid and liquids, and learn when objects will sink and float in the water.

Introduction(6 marks)

Density is the measurement of the amount of mass that fits within a specific volume. There are two factors that density depends on which are mass and volume, the equation of density is D= M/V, higher density= higher mass, and lower volume, and higher mass means higher density, and higher volume means lower density. The units for density are grams per cubic centimeter ( g/cm3** ) or grams per milliliter ( g/ml ), since a cubic centimeter is equivalent to a milliliter.

An object will sink or float depending on its density, when Density greater than 1 an object will sink in the water and when density is less than 1 an object will float in the water. Heavy things not always sink and light things not always float for example real boats are heavy and still float. Sinking or floating has to do with the amount of water pushed out of the way. To predict whether an object will sink or float in a liquid, you must first examine the densities of both the object and the liquid. If the object is denser than the liquid, it will sink. If the object is less dense than the liquid it will float. For example, the density of water is approximately 1g/ cm3. The density of ice is approximately 0.92 g/ cm3. That is why when water freezes, the ice floats on the top rather than sinking to the bottom.

Methods (5 marks)

• Materials were used are irregular shape (ball), regular shape (cuboid), 4 different salt solution, beaker, balance, graduated cylinder.

•Density of solid irregular shape (ball) part (1A): first, use balance to find the mass of the object and record the value on the data chart. Second, pour water into a cylinder and record the number. Third, drop the object into cylinder and record the new value in millimeters. The fourth step is finding the object volume by measuring the difference between the two and record the volume on the data chart. Fifth, use density formula to find the object’s density through dividing the mass by the volume and record the density on the data chart.

•Density of solid regular shape (cuboid) part (1B): first, measure the mass of the object by using the balance then record the value on the data chart. Second, measure the length, width, height by using the metric ruler or diameter of the object. Third, compute the volume of the object by multiplying the L*W*H after that record the volume on the data chart. Fourth, determine the density of the object by dividing the mass by the volume value. After that record the density results on the data chart.

•Density of liquid part (2): take mass of an empty beaker record in grams (m3). After that, use the measuring cylinder to take 44 ml from a salt solution and record it as volume (v5). Measure and record the beaker plus solution to find m5 in grams. Find the mass solution by subtracting m5 from m3. Then find the density by dividing mass over volume. Repeat the procedure for other solutions and draw a graph to determine unknown solution concentration.

Results (4 marks)

Part (1):

Object (1).. Ball

The mass of the object (m1) = 9.850 g.

The level of water in graduated cylinder (v1) = 40 ml.

The level of water with object in cylinder (v2) = 48 ml.

The volume of the object (v3) = (v2 – v1) = (48 – 40) = 8 ml.

The density of the object (D1) = ( mass ÷ volume) = ( 9.850 ÷ 8) = 1.1975 g/ml.

The object will sink when placed in the water because it has a density more than 1.

Object (2) .. cuboid (Rectangular)

The length of object (L) = 5.8 cm.

The width of object (W) = 3.2 cm.

The height of object (H) = 3.2 cm.

The volume of object (v4) = (L × W × H)= (5.8 × 3.2 × 3.2)= 59.392 cm^3.

The mass of object (m2) = 40.8854 g.

The density of object (D2) = ( mass ÷ volume) = ( 40.8854 ÷ 59.392) = 0.6884 g/cm3.

The object will float when placed in the water because it has a density less than 1.

Part (2):

The density of (5%) Solution = ( mass ÷ volume) = ( 43.1443 ÷ 44) = 0.980 g/ml.

The density of (15%) Solution = ( mass ÷ volume) = ( 29.5661 ÷ 30) = 0.99 g/ml.

The density of (25%) Solution = ( mass ÷ volume) = ( 31.552 ÷ 31) = 1.018 g/ml.

The density of Unknown Solution = ( mass ÷ volume) = ( 53.3631 ÷ 54) = 0.988 g/ml.

Graph:

Unknown concentration determined from graph: 9.8%

Discussion (12 marks)

Provide a full answer for each one of the following questions:

Using your result for part (1), discuss whether the two solid objects you used would sink or float if they were placed in water, and explain the reason using your own data.

Based on the proved theory Sinking and Float it states that an object will sink if its density is greater than 1 and the object will float if its density is less than 1. In Part (1)A our first object was a plastic ball. When we measured its density it was 1.1975 g/mL as a result we knew that the ball will sink. In Part (1)B our second object was a cuboid. When we measured its density it was 0.688 g/cm3 as a result we knew that the cuboid will float.

Describe the relationship shown in the graph you generated for part (2) i.e. what happened to the density of water as the concentration of the salt was increased?

The graph shows a positive relationship between the density and the concentration of the salt. This means that when the concentration of the salt increases the density will also increase.

Using your data for part (2), if you have a carrot slice that has a density of exactly 1.005 g/mL. In which salt solutions it will sink, and in which one it will float? Explain the reason using your own data.

An object will float if it less dense than the solution and it will sink if it more dense than the solution. This means the carrot slice will sink in the 5%,15% and 9.5% solutions. Since the density of the carrot slice is 1.005 g/mL and 1.005 g/mL > 0.980 g/mL (5% solution), 1.005 g/mL > 0.99 g/mL (15% solution) and 1.005 g/mL > 0.988 (9.5% solution). However it will float in the 25% solution. Since the density of the carrot slice is 1.005 g/mL and 1.005 g/mL < 1.01 g/mL (25% solution).

If you know that the true value of the unknown solution is exactly 10%. How does this compare to the value you got from your graph? List some errors that may have caused the variation in the two values.

The value we got from our graph was 9.5%, which means we are 5% away from the actual true value. The errors that may have caused the variation between the two values are having the balance zeroed incorrectly, reading liquid inside the cylinder incorrectly, drawing the graph incorrectly.

Answer the following questions:

You have a rock (called A) with a volume of 3 mL and a mass of 60 g. What is its density?

Density = Mass/Volume

Density = 60 g/3 mL = 20 g/mL

You have a different rock (B) with a volume of 2 mL and a mass of 120 g. What is its density?

Density = Mass/Volume

Density = 120 g/2 mL = 60 g/mL

In the above two examples which rock is heavier? Which is lighter?

Rock (B) is heavier than rock (A) because it has a larger mass, while rock (A) is lighter than rock (B) because it has a smaller mass.

In the above two examples which rock is more dense? Which is less dense?

Rock (B) is more dense than rock (A) because it has a larger density while rock (A) is less dense than rock (B) because it has a smaller density.

Which one do you think will sink in water and which one will float?

It’s a known fact that the density of water is 1 g/mL, we learned that if the density is larger it’s going to sink while if it’s smaller it’s going to float, sense both densities are larger than the density of water both rocks will sink.

Conclusion (0.5 marks)

Methodology learned of measuring density of regular and irregular solid.

Placement unknown solution by using the density.