Chapter 1 - Laboratory

Are beakers accurate for measuring volume?

Beaker glassware is not very accurate and therefore is not a good choice for measuring volumes.

What are beakers primarily used for?

Beakers are useful for heating, mixing, or stirring solutions

What is the graduated cylinder used for?

Used to measure variety of volumes

What is the correct method of measuring the meniscus?

Measure the bottom of the meniscus

Can Erlenmeyer flasks be used for mixing, heating, and stirring of solutions?

Yes

Are Erlenmeyer flasks accurate enough for volume measurements?

No

What are boiling flasks primarily used for?

Swirling and heating liquids

What is the most precise glassware available for measuring liquid volumes?

Pipettes

In what situations is a buret commonly used?

Most commonly used in titrations

What does the stopcock do for a buret?

Used to control amount of liquid released by buret

Can test tubes be used for mixing various solutions?

Yes

Should test tubes be used for measuring volumes?

No

The amount of gas provided to the Bunsen burner is related to what?

The size of the flame

Should you calibrate your pH meter prior to or after use?

pH meter should always be calibrated prior to use

What device can you use in chemistry labs to accurately measure the mass of a solid sample?

Digital balances

What does the term 'graduated' mean?

"Graduated" refers to any glassware that has several markings indicating different volume level

What does the term 'volumetric' mean?

The term "volumetric" refers to any glassware that has a single marking that indicates a specific volume

Is volumetric glassware more accurate than graduated glassware?

Yes.

What is the order of precision from most precise to least precise glassware?

Pipettes > Burets/Volumetric Flasks > Graduated Cylinders > Beakers/Erlenmeyer flasks

When is it alright to place the sample directly onto the digital balance?

It is never alright to place the sample onto the balance directly

Assuming you are using a digital balance, what is the step by step process for measuring the mass of a sample?

Turn on digital balance, tare weighing paper or glassware, then proceed to place sample on

What is the purpose of titration?

To measure the volume of the titrant needed to react completely with the other reagent.

What is the term that describes any deviation of the endpoint from the equivalence point?

Titration error

What is the term that describes the point at which the added titrant has completely reacted with the reagent?

Equivalence point

The color change that occurs at the endpoint is associated with what?

Associated with either being at or near the equivalence point.

What occurs during centrifugation?

The mixture is spun at very high speeds and the resulting centrifugal force acts upon the heavier components of the mixture (the solids) such that they move towards the bottom of the vessel and form the pellet

When separating a solid pellet from a liquid supernatant, which agent do you expect to be on top?

The liquid supernatant will typically lie on top of the solid pellet, unless the pellet is less dense than its liquid counterpart

What is calorimetry used for?

A method used across general chemistry labs to measure the amount of heat energy that is released or absorbed during a chemical reaction

What does the most basic calorimetry setup entail?

A Styrofoam cup sealed by a lid along with a thermometer that protrudes through the lid and into the cup

What does precision refer to in a lab setting?

Precision refers to the consistency of measured experimental values such that all values should be relatively close to each other.

What does accuracy refer to in a lab setting?

Accuracy refers to how close a measured experimental value, such as the melting point of a compound, is to the actual literature value for that compound

Is it possible for a set of values to be precise, but not accurate?

Yes

Is it possible for a set of values to be both precise and accurate?

Yes

Is it possible for a set of values to be neither precise nor accurate?

Yes

Why are significant figures used in laboratory settings?

To describe uncertainty of a specific measurement

What are the three main rules for significant figures?

1. Non-zero numbers are always significant

2. Zeroes that are between two non-zero numbers are also significant

3. Trailing zeros, in the decimal, are significant

When multiplying or dividing, the final answer is expressed in significant figures based on what?

The lowest degree of significant numbers involved in the multiplication or division

When adding or subtracting, the final answer is expressed in significant figures based on what?

The final answer is rounded to the digit of least accuracy

Between systematic error and random error, which one is more likely to depend on human error?

Random error

What does systematic error refer to?

Systematic errors tend to be consistent shifts in one direction of a measurement that often result from faulty equipment or an error in the procedure

What does random error refer to?

Random error is one that is not consistent but can vary in either direction. These are often the result of human error such as in the example of reading the markings on a piece of glassware

When should the safety shower be used over the eye wash station?

When one has been exposed to toxic or corrosive chemicals extensively across the body or if clothing has been caught on fire

When should the eye wash station be used over the safety shower?

When one needs to treat splashes of chemicals in or near the eye region. Thoroughly rinse both eyes for at least 15 minutes

How should acids, alkalis, and other water miscible solutions be disposed of?

Acids, alkalis, or other water miscible solutions can be flushed down the drain with adequate amounts of water

Can organic and water immiscible solutions be disposed down the drain?

Organic and other water immiscible chemicals should not be flushed down the drain

How should organic and water immiscible solutions be disposed of?

Pour into appropriate waste bin in laboratory

Is it ok to eat in the lab?

No, as there are potentially hazardous chemicals present in the lab