chemistry

Laboratory 3. Measurement of Mass and Temperature.

Background

Mass is a measure of the “amount of matter in an object”. The weight of an object is related to the force acting on the object due to gravity. While the attraction due to gravity (weight) can change based in the location, the amount of matter (mass) remains always the same. Based on this definition, let us compare the mass and weight on a person on Earth, Moon, and Jupiter.

	Earth	Moon	Jupiter
Mass (kg)	68.0 kg	68.0 kg	68.0 kg
Weight (lbs)	150 lbs	24.9 lbs	379 lbs

Here on Earth there is not much meaningful difference between mass and weight, and the distinction is often ignored.

On Earth (and only on Earth) we can use the conversion factor 1 kg = 2.2046 lbs.

(A). Measurement of Mass

The basic unit to measure mass is the gram (g), and the SI unit of mass is the kilogram (kg). There are 1000 grams in 1 kg (1000 g = 1 kg).

In this laboratory, you will use a top load balance and an analytical balance to measure mass. The picture below two types of balances. The difference is in their precision, and therefore in the number of significant figures in the data collected. One in the video is of less precise type.

Balance	Analytical balance

“Tare” is act of removing a known mass of an object, usually the weighing paper/container, to zero a scale.

1. Measurement: Length, Volume, mass and Temperature (13 mins)

https://www.youtube.com/watch?v=xhZnzvuHWb0

mass from 8 min, temp from 11:40 min

Watch the above video to fill out the mass measurement data sheet

DATA SHEET:

Part 1. Measurement of Mass – Mass of paper clips

1a. Mass of weighing boat (tared): ________ ______________

1b. Mass of weighing boat + paper clips _________ _____________

1c. Calculate the mass of paper clips: __________ ____________

Compare the results of top load and analytical balance and comment on the observed values.

Part 2. Measurement of Mass – Mass of marbles

2a. Mass of weighing boat (tared): ___________ ____________

2b. Mass of weighing boat + marbles: ___________ ____________

2c. Calculate the mass of marbles: ___________ ____________

Compare the results of top load and analytical balance and comment on the observed values

Part 3. Measurements of Mass – Mass of pennies

3a. Mass of weighing boat (tared): ____________ ____________

3b. Mass of weighing boat + pennies: ____________ ___________

3c. Calculate the mass of pennies: _____________ ____________

Compare the results of top load and analytical balance and comment on the observed values

Part 4. Answer the following questions.

4a. In the laboratory, do we determine the mass or the weight of an object?

Temperature is a measure of the average kinetic energy (energy associated with motion) of the particles in an object. In simpler words, temperature is a measure of how hot or cold something is (but the terms hot and cold are not very scientific terms)

Temperature Scales

The picture below shows the three thermometers in the most common temperature scales:

· Fahrenheit (°F) is the temperature scale employed in the English system.

· Celsius (°C) is the temperature scale employed in the Metric system.

· Kelvin (K) is temperature scale of the International System (SI). Also referred as the absolute scale (No negative values for temperature)

When reading a glass thermometer, make sure to play attention to the following details:

· Temperature range: lowest and highest temperatures that can be measured

· how many units does each dividing line represents: important for significant figures

The following formulas can be used to convert between temperature units:

(B). Measurement of Temperature

In the experiment today, we will be watching use of an alcohol/mercury and a digital thermometer to measure water temperature under different conditions.

Watch these three videos and write down temperatures at appropriate rows.

2. Temperature measurement of water at different conditions: (3 min) must use correct sig figures

https://www.youtube.com/watch?v=QB_n3xpFcUM

3. water: boiling, RT and ice/water: (6 min)

https://www.youtube.com/watch?v=MPFeF6pUu4k

4. Measurement: Length, Volume, mass and Temperature (13 mins)

https://www.youtube.com/watch?v=xhZnzvuHWb0

mass from 8 min, temp from 11:40 min

freezing point and boiling point of water, as well as temperature of water at RT or some other higher temperature.

The freezing point is the temperature at which a substances changes from liquid to solid (and liquid to solid, also called the melting point).

The boiling point is the temperature at which a substances changes from liquid to gas. It is also the same temperature at which a gas condenses to liquid.

Part 5. Measurement of Temperatures

DATA:

5a. Temperature of ice and water (A): ____________________

____________________

5b. Temperature of lukewarm water (B): ____________________

5c. Temperature of hot water (C): ____________________

5d. Temperature of RT water: ____________________

5e. Temperature of tap water: ____________________

5f. Temperature of ice and water and salt: ____________________

5g. Temperature of boiling water: ___________________

5h. Compare 5a and 5f. What is the effect of adding the NaCl on the freezing point?

Videos:

https://www.youtube.com/watch?v=zel6h8ssLbg

https://www.youtube.com/results?search_query=measurement+of+mass+and+temperature