Science Lab Safety and Phases of Matter

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Questions and Answers

Why is it dangerous to wear contact lenses in the lab? (Select all that apply)

The plastic reacts with acids

They don't protect well enough

Glasses protect better than lenses

Liquid can be trapped under them (correct)

Why should you never use a CO2 based extinguisher on a person?

CO2 is toxic

CO2 is freezing cold (correct)

The person would suffocate

CO2 is corrosive

What do you have to do before leaving the lab, to make sure you don't carry traces of chemicals outside?

Take off your lab coat and wash your hands

What is the first thing you have to do if there is a fire in the lab?

Alert people Signup and view all the answers

What kind of phase change is happening to particles that transition from a solid to a gas state?

Sublimation Signup and view all the answers

What kind of phase change is happening to particles that transition from a gas to a solid state?

Deposition Signup and view all the answers

What kind of phase change is happening to particles that change from a gas to a liquid?

Condensation Signup and view all the answers

Which of these is NOT matter?

Light Signup and view all the answers

To which of the three main chemical classes does Mercury (Hg) belong?

Metals Signup and view all the answers

What are the different colors caused by that we could see in the flame test?

Electrons falling back into their original shell Signup and view all the answers

Which groups of elements have a full octet of electrons?

Noble gases Signup and view all the answers

In the standard periodic table, what does the atomic number represent?

Number of protons Signup and view all the answers

What does KCl actually stand for?

Potassium chloride Signup and view all the answers

What happens when ionic compounds dissolve in water?

Cations and anions are released into the solution Signup and view all the answers

What's the charge of the K ion?

+1 Signup and view all the answers

When K+ and Cl- form an ionic bond, how are they held together?

It's held together by electrostatic forces Signup and view all the answers

Which are the subatomic particles of an atom?

Protons - neutrons - electrons Signup and view all the answers

How many electrons are in the atom of Magnesium (Mg)?

12 electrons Signup and view all the answers

What is the Atomic Number of Lithium?

3 as the number of protons Signup and view all the answers

How many protons does Potassium have?

19 protons Signup and view all the answers

How can we count how many atoms and molecules there are?

You count them by mass Signup and view all the answers

How many moles of AgNO3 silver nitrate should we use to be sure that we have excess?

0.100 mol Signup and view all the answers

Why are only sterile pipette tips used in the lab?

To avoid contamination of the sample Signup and view all the answers

Why did you press the plunger all the way down to the second stop of the pipet?

To push out the remaining fluid from the tip Signup and view all the answers

What do you need to do next before pipetting a different sample?

Discard the tip Signup and view all the answers

How can we reduce the concentration of protein in our sample?

Dilute the sample Signup and view all the answers

What was the first step of using the balance, before adding anything to a weighing dish?

Tare the balance with the weighing dish Signup and view all the answers

Study Notes

Lab 1: Safety in the Lab

Contact lenses are dangerous in the lab because liquids can be trapped under them. This can cause eye irritation or infection.
CO2 fire extinguishers should not be used on a person because CO2 is freezing cold and can cause frostbite.
Before leaving the lab, you should take off your lab coat and wash your hands to prevent carrying chemicals outside.
The first thing to do in case of a fire is to alert people. Then, you can take other safety measures like opening windows or using a fire extinguisher.

Lab 2: Phases of Matter

Sublimation is the phase change from a solid to a gas.
Deposition is the phase change from a gas to a solid.
Condensation is the phase change from a gas to a liquid.
Light is not matter because it does not have mass or volume.

Lab 3: Elements and Periodic Table

Mercury (Hg) is a metal. It is a liquid at room temperature.
Flame tests produce different colors when electrons fall back into their original shell after being excited.
Noble gases have a full octet of electrons, which means they have eight electrons in their outermost shell.
The atomic number represents the number of protons in an atom.

Lab 4: Ionic Compounds

KCl stands for potassium chloride.
When ionic compounds dissolve in water, cations and anions are released into the solution. This is because the water molecules pull the ions apart.
The K ion has a charge of +1. This is because it has lost one electron.
Ionic bonds are held together by electrostatic forces. This means that the oppositely charged ions attract each other.

Lab 5: Atomic Structure

The subatomic particles of an atom are protons, neutrons, and electrons.
Magnesium (Mg) has 12 electrons. The number of electrons in a neutral atom is equal to the number of protons.
Lithium has an atomic number of 3 because it has 3 protons.
Potassium has 19 protons.

Lab 6: Moles and Stoichiometry

Atoms and molecules are too small to be seen with a microscope, so they are counted by mass. This is done using the concept of moles, which represent a specific number of particles.
To have an excess of silver nitrate (AgNO3) in a reaction, you should use 0.100 mol. This ensures that there will be enough AgNO3 to react with any of the other compounds.

Lab 7: Pipetting Techniques and Bradford Assay

Sterile pipette tips are used to avoid contaminating samples. Contaminated tips can introduce unwanted substances into the sample.
The plunger is pressed all the way down to the second stop to push out the remaining fluid from the tip. This ensures that the correct volume is dispensed.
Before pipetting a different sample, you should discard the tip. This prevents cross-contamination between samples.
To reduce the concentration of a protein sample, you can dilute it. This involves adding more solvent to the sample.

Lab 8: Using a Balance

Before adding anything to a weighing dish, you should tare the balance. This zeros the balance so that it only shows the weight of the substance being added.

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Description

This quiz covers essential safety practices in the laboratory, the phases of matter, and an introduction to elements and the periodic table. Test your knowledge on lab safety procedures, such as proper use of fire extinguishers and safe handling of materials, as well as your understanding of different phase changes. Ideal for students in introductory chemistry or science courses.