“We must trust to nothing but facts: These are presented to us by Nature, and cannot deceive. We ought, in every instance, to submit our reasoning to the test of experiment, and never to search for truth but by the natural road of experiment and observation.” ― Antoine Lavoisier, Elements of Chemistry


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Friday, 30 August 2013

Laboratory Techniques, Safety in The Laboratory worksheet

What Are They Doing Wrong??

List what are they doing wrong in the picture below.

Wednesday, 21 August 2013

Scientific Methods Worksheet

Scientific Method Worksheet
Name :
Class/# :
Day, date :

Step 1: Put the steps of the scientific method in the correct order.

Do background research
Ask a question
Analyze results
Construct a hypothesis
Draw conclusions
Test with an experiment

Step 2: Using the below synopsis, match each of the steps of the scientific method to its corresponding statement.

Synopsis: Jenny has been working hard all summer on her tomato garden. Recently, she noticed that
insects have been eating her tomatoes and tomato plants and she is worried about spraying them with harmful, store-bought pesticides.

Jenny states that if she sprays her vegetables with a natural, homemade solution to help fight
the bug problem, then her vegetables will still grow to the same size as they would if she used
store bought pesticides____________________________

Jenny sprays one third of her vegetables with store bought pesticides , one third of her vegetables with her homemade solution, and does not spray the remaining third (her control group) ____________________________

After one week, Jenny compares and tests the differences in her vegetables____________________________

Jenny wonders how she can protect her plants from bugs without harming the

Jenny determines that her homemade solution was just as effective as the store-bought

Jenny goes to the library and looks up different kind of pesticides and their effect on vegetables and also looks up natural remedies to help solve her bug problem____________________________

Identify the independent variable and the dependent variable.

1. Christine investigated how fast one year old Persian cats reacted to different whistles.

Independent Variable ______________________________________________
Dependent Variable _______________________________________________

2. Identify the independent variable, dependent variable, and constants.
Mario studied how far room temperature tap water would spurt out of a plastic milk carton when 3 mm holes were punched at different heights from the bottom of the container.

Independent Variable ______________________________________________
Dependent Variable _______________________________________________
Constants _______________________________________________________

3. Identify the independent variable and dependent variable in each hypothesis.
a. If different motor oils are put in water, then they will float at different heights on the water.

Independent Variable________________________________________
Dependent Variable __________________________________________

b. If the number of twists of a rubber band is increased, then a toy propeller airplane will fly farther.

Independent Variable ________________________________________
Dependent Variable __________________________________________

4. Determine if the hypothesis is supported by the data and explain your answer.
Lamont knew that water made things look larger. He wondered what other liquids such as alcohol and glycerin would do. Lamont thought a pencil would look larger in the thicker liquid (glycerin), followed by water, and then alcohol. In the experiment he rated the increase in pencil size from 1 to 10, with 10 as the largest. His rankings were 7 for glycerin, 5 for water, and 2 for alcohol.


5. Make a hypothesis about the following using an “If . . . , then . . . “ statement.
a. The time for different size water drops to fall through vegetable oil.

b. How high an ice cube will float in different temperatures of water.

Thursday, 1 August 2013

Safety In the Laboratory


Entering and leaving the laboratory:
1. Do not run
2. Make sure that school bags are stored safely
3. Put stools under the bench when not in use
4. Leave the bench clean and dry

General Behavior:
1. Do not run in the laboratory
2. Do not eat or drink in the laboratory
3. Work quietly

During Experiment:
1. Never point a tube test containing chemical at anyone, and do not examine the content by looking down the tube.

2. Tell your teacher about any breakage or spillage at once. If you are at all unsure of the practical work, check with your teacher that you are following the correct procedure.

3. Only carry out investigations approved by your teacher, and use the gas, water, and electricity supplies sensibly.

Hazard Warning Symbols

chemistry - checkpoint 
Hazard Warning Symbols

(can easily ignite and burn: benzene, ethanol)

Give off harmful rays that can kill living cells: uranium, radium
Chemicals that explode: toluene
Chemicals that may present an immediate or delayed danger to one or more components of the environment
Destroy living tissue, including the skin and eyes: concentrated acid, oven cleaner
The substance provides oxygen.
Other materials will burn more fiercely in its presence.

Involved a health risk or irritate the skin: dilute acid, alkalis, thinner


poisonous if breathed, absorbed through the skin: alcohol, mercury