Lab Safety

Waft liquids

When diluting acid, pour acid into water

Acid and water mixed together may cause an exothermic reaction

Keep your goggles on until Mr. Leeds says to remove them

Nurse Ext: 2828


Ch. 1:

Observation- information obtained by the senses- often by direct measurement

Inference- a conclusion based upon known observations

Hypothesis- A proposed solution to a scientific problem

Control Group- the group that is the standard for comparison in any experiment

Experimental Group- the group receiving the variable being tested

Control Factors- the variables that are held constant. They are the same for both the control group and the experimental group

Indicator- a substance used to show the presence of another substance

Volume- the amount of space something occupies. True of solids, liquids, and gases

Volume displacement technique- quick and easy way to determine the volume of a solid or gas

Mass- the amount of matter in a substance (true of solids, liquids, or gas)

Meniscus- the curved portion of a liquid when in a container. Must read the bottom of the meniscus at eye level for a proper measurement

Ch. 2:

Histogram- a bar graph that shows the # of times a value is represented for a large sampling group

Conservation of Mass- in all changes, mass is exactly conserved, provided nothing is added or allowed to escape. MUST BE A CLOSED SYSTEM. Not true for volume

Laws of Nature- guessed generalizations based on many experiments. Can be adjusted when necessary to account for any changes in the limitation of a law

Ch. 3:

Characteristic Properties- properties that show differences between substances. ex: density, boiling point, solubility, melting point

Plateau- the flat portion of a graph. Indicates no change in the dependent variable (y-axis)

Phase Diagram- a graph that shows the changes in state of matter for any substance. Represents physical changes in the substance

Barometer- used to measure atmospheric air pressure. Contains a column of mercury and a metric scale in a sealed container

Barometric Pressure- air pressure generated by the atmosphere

Density- Mass per unit volume of any substance. Unit of measure is g/cm^3

Scientific Method

1. Identify problem

2. Gather info

3. Form hypothesis/theory

4. Perform experiment

5. Analyze date

6. Conclusion

Reaction in a Bag lab

Purpose: to record observations that occur when substances are combined

Experimental Error:

-having an undetectable hole in your baggie, which would have resulted in not being able to see that the bag inflates with gas because the gas would have escaped!

Baking Soda Lab

Purpose: to observe and record the reaction that occurs when baking soda is heated

Experimental Errors:

-Small hole in tubing, which would have resulted in gas escaping from the bottle and not allowing you to see there was a gas!


- baking soda... gas is SODIUM BICARBONATE

- indicator... the tea

Volume Notes

unit of measurement: cm^3

formula: l x w x h

standard unit of length: meter (m)

1 cm= 0.01 m

100 cm= 1 m

unit cube: a small cube with 1 cm on each edge

Volume of Liquids:

-use a graduated cylinder to measure **always check intervals or scale**

-units= mL or cm^3

Single Pan Balance

1. Check that pan is clear and dry

2. Always zero balance before EACH massing

3. Never switch pans

4. Pick up balance by red bar only

5. Return riders to zero when done

Measuring Volume by Displacement of Water Lab

Purpose: to use the displacement of water method to measure the amount of dry sand that is sand and airspace

Experimental Errors:

- Pouring water into sand, volume of sand in water increases

Sensitivity of a Balance Lab

Purpose: to discover the sensitivity of your balance and to see if when you mass the same object repeatedly will you find the same mass.

Experimental Errors:

-pencil marks on paper----> mass increases


Sensitivity: change in mass/# of changes

Balances sensitivity: 0.02 (means that balance has margin of error +or- 0.02 g)

Mass of Dissolved Salt Lab

Purpose: to discover if the mass of the salt decreases as the salt dissolves in water

Experimental Errors:

-cap is not on tight ---> water spills out, mass decreases

Mass of Ice Lab

Purpose: to determine if when ice melts does its mass change along with its volume

Experimental Errors:

- Removing cap before mf ---> mass decreases


Condensation comes from warm water vapor touching the cooler surface of the bottle. It changes the gas to a liquid

Mass of Copper and Sulfur Lab

Purpose: Does the total mass of copper and sulfur change when they are heated together?

Experimental Errors:

- rubber sheet not on tight ---> decrease in mass

Mass of a Gas Lab

Purpose: To see if when a liquid and solid produce a gas, will the mass change

Experimental errors:

- inside of cap is wet, tablet reaction starts early ---> decrease in mass

Law of Conservation of Mass

In a closed system, mass will remain constant, regardless of the actions of the processes inside the closed system

When salt dissolves in closed system----> same mass

When ice melts in closed system-----> same mass

When copper and sulfur are melted in closed system----> same mass

When liquid and solid produce a gas in closed system---> same mass

Mass and Volume Lab

Purpose: to determine if the mass of a 1cm^3 object will depend on its shape or the substance its made of

Experimental Errors:

-water splashing out of graduated cylinder --->volume decreases

Mass Volume Notes

Objects that are made of the same substance that have the same volume will have the same mass (regardless of their shape)

The mass of an object will double if its volume doubles

Objects that have the same volume but are made of different substances will NOT have the same mass



Units: g/cm^3

Function of= x-axis

Graph of= y-axis

Density of Solids Lab

Purpose: to use density to compare 3 metal objects to see if they are made of the same substance

Experimental Errors:

-Measure from end of ruler and not 0---> volume decreases, density increases


All rocks have different densities because rocks are formed by different substances being compressed together. Different substances=different densities

Density of Liquids Lab

Purpose: to use density to compare 2 liquids to see if they are the same substance

Experimental Errors:

- liquid sticks to inside walls of cylinder---->mass increases, density increases


-More accurate to find mass and volume of liquid in same container so you don't lose liquid while pouring!

- Epson Salt---> Magnesium Sulfate

Density of Gas Lab

Purpose: to produce and collect a gas in order to accurately find the density of the gas

Experimental Errors:

- Water in pan during mass final ---> mass decreases, density decreases

- Hand not sealed on bottle while inverting it, water leaks ----> volume increases, density decreases


- Sodium Bicarbonate produces gas called carbon dioxide!