OChem Lab Final
The number of amino acids that exist in the human genetic code Natural amino acids
20
Gel electrophoresis is a method used to separate fragments of biomolecules such as _______. After loading a sample onto a gel, a ______ is applied. The sample is separated as the fragments _____.
DNA; current; travel across the gel
How can you improve your ability to see the indicator color change at the endpoint of a titration?
Place a piece of white paper under the analyte flask throughout the titration
Which statements accurately describe soap?
Soaps are both hydrophobic and hydrophilic Soaps should be weakly alkaline in solution Soaps react with ions in hard water to create a precipitate
Under what conditions should a student inform the instructor of a lab injury?
The instructor must be informed of all laboratory injuries
A negative Benedict's test appears as ________.
a blue solution
A polymer is _______ made of _________, known as ________. Polymers can be natural, such as _______, or synthetic, such as ________.
a macromolecule; many repeated subunits; monomers; proteins; plastics
A positive Benedict's test appears as ______.
a reddish precipitate
When testing the pH of a solution with pH or litmus paper, dip _________ in the solution. Add a ______ of the solution to the paper. Compare the _______ of the pH paper to the scale that appears on the container
a stirring rod; drop; color
An indicator is a substance added to a sample that has ____ change, such as a _______ change, in response to the ______ of the sample
a visible; color; chemical composition
A negative iodine test appears as _______
a yellowish solution
While pulling an empty beaker off the shelf at the beginning of lab, it slips out of your hand onto the floor.
closed-toe shoes
Identify the expected result of the iodine test with different carbohydrates. starch sucrose amylopectin glucose
color change no reaction no reaction no reaction
In general, which characteristics are necessary for a location to be suitable for chemical storage?
dry; cool; dark
recommended personal protective equipment (PPE)
exposure controls / personal protection
If you drop or break glassware in lab, first ________. Then, ________. Finally, place all that material into the _________.
get thick gloves or dustpan; carefully collect all the broken glassware; broken glass container
While picking up a buret, an unknown solution left by a previous solution drips onto your hand.
gloves
chemical name and formula
identification
A reagent added to the analyte solution that changes color when the reaction is complete
indicator
While transferring a solution from a flask to a beaker, the solution accidentally spills down the front of the lab bench.
lab coat
Determine which items of personal protective equipment (PPE) you will likely use in a general chemistry lab.
lab coat; goggles; gloves
Octyl formate is an ester that has the flavor of oranges. It can be synthesized from an alcohol and a carboxylic acid. What alcohol is needed to make octyl formate? what carboxylic acid is needed to make octyl formate?
octanol; formic acid
What elements make up a carbohydrate?
oxygen, carbon, hydrogen
Solution of known concentration that is slowly added to a solution of unknown concentration
titrant
Process of slowly adding a solution to react with another solution and determine the concentration of one of the solutions based on the reaction between them
titration
A unit commonly used in spectrophotometry that is inversely proportional to energy and commonly measured in nanometers
wavelength
Which is NOT a good source of information about the hazards that affect waste disposal in a chemistry lab?
your lab partner
Fill in the words to complete the steps in the process of recrystallization.
1. Dissolve a substance in a minimal amount of hot solvent 2. Allow the solvent to cool, precipitating the substance while impurities remain in solution 3. Filter the mixture to collect the pure substance
The number of amino acids that can be made by the human body Nonessential amino acids
11
The number of amino acids that humans require through diet Essential amino acids
9
Using the letters on the image, identify the significance of each section on the NFPA diamond.
A - health B - flammability C - reactivity D - special hazards
What information does not need to be included a chemical waste label?
A description of the experiment the chemicals were used for
What visible signs indicate a precipitation reaction when two solutions are mixed?
A hazy or cloudy appearance Solid settling out in the test tube
How can you remove the protein casein from a sample of non-fat milk?
Add acid to change the protein's tertiary structure, which triggers solid formation.
Which statement concerning the effectiveness of enzymes is NOT true?
Although the actions of different enzymes may vary, the effectiveness of each particular enzyme is constant.
What are the best practices for safely handling waste in the lab?
Always wear appropriate Personal Protective Equipment Check labels or instructions before any disposal
What is a protease?
An enzyme that breaks down a protein into individual amino acids A protein consisting of a chain of amino acids A component of foods such as fruit juices
Determine when to put on disposable gloves for work in the lab.
Before handling any glassware or chemicals for the experiment
What are lipids?
Biological molecules characterized by solubility in organic solvents
A student removes a chemical sample from a reagent bottle to be used in an experiment. What should he do with any excess chemical remaining from this sample after the experiment is complete?
Check and see if anyone else can use the chemical. If not, discard in the proper waste container.
After an electrophoresis experiment, how are the lengths of the DNA fragments in each lane determined?
Comparing to a standard DNA ladder in one lane
Identify the step that is not recommended when responding to an emergency.
Gather your belongings
Which types of signs are posted to convey information about chemical storage?
Hazard signs such as "Flammable," "Oxidizer," and "Corrosive" National Fire Protection Association (NFPA) diamond Gas Cylinder sign
Identify the types of information that are necessary to communicate with emergency responders.
How the incident happened Any chemicals involved in an incident Any other hazards present in the lab
Read the Safety Data Sheet (click SDS icon below) of hydrogen peroxide to identify the recommended way to store this substance.
In a tightly closed container in a dry and well-ventilated place
Which tests show can be used to show that a phenol is present?
Iron(III) chloride test; Acidity test
All lab participants must remain prepared to use safety equipment in case of emergency. Identify the components of effective preparation.
Knowing what safety equipment is available Understanding where the safety equipment is located Being familiar with how safety equipment is used
Identify the precautions to take with exits in the lab.
Locate the exits prior to the start of lab Do not block a door with an EXIT sign
How should students prepare to use chemicals in the lab?
Locate the spill kits and understand how they are used. Become familiar with the chemicals to be used, including exposure or spill hazards.
What effect do restriction enzymes have on DNA?
Restriction enzymes cleave DNA at specific sequences into fragments.
Read the Safety Data Sheet (SDS) (click the SDS icon below) of hydrogen peroxide to identify the type of eye protection recommended when handling this substance.
Tightly fitting safety goggles
Determine the safest option in the lab if you need your vision to be corrected.
Wear corrective glasses or lenses under your safety goggles for the whole experiment, but always check with your TA or Instructor for your school's policy
Determine when you should remove your goggles in the lab room.
When everyone in the room is done handling any chemicals or glassware
When should you start a new chemical waste container in the lab?
When the contents of the current container are a couple inches below the brim of the container
Form hydrogen bonds amongst themselves and have lower vapor pressure
carboxylic acids
Their reactions with base are known as neutralizations
carboxylic acids
Usually have a sour odor
carboxylic acids
A polymer formed as monomers link together, forming a small molecule as a byproduct.
condensation polymer
Which metal is responsible for the color change in a Benedict's test?
copper
When using acids and bases, note that these substances are _______. Make every effort to avoid contact with ________. Be sure to wipe up any spills ________.
corrosive; the skin and lab surfaces; immediately
A square-shaped container, typically made of quartz, designed to hold samples in a spectrophotometer
cuvette
In general, alcohols ______ when mixed with water because the _______ in alcohols can _________ water.
dissolve; O-H bonds; hydrogen bond with
Iron(III) chloride can be used to assess the purity of aspirin synthesized from salicylic acid. Iron(III) chloride _______ react with asprin because the reaction requires __________ which is present in __________.
does not; a phenolic functional group; salicylic acid but not aspirin
Soaps clean up dirt by acting as ________. The nonpolar chain in the soap is attracted to the ______ and the ionic end is attracted to the _________. Thus, the soap creates ________ that wash the dirt away with the water.
emulsifying agents; dirt; water; dispersed droplets
When the required amount of one solution has been added to the second solution to complete the reaction
endpoint
Do not form hydrogen bonds amongst themselves and have higher vapor pressure
esters
Notable for their pleasant fragrances
esters
Their reactions with base are known as saponifications
esters
Beverages are allowed in lab as long as they are in containers with lids.
false
Chewing gum is okay in the lab as long as you don't blow bubbles.
false
Saponification is the process of making soap from ______. The reaction is a type of _______ that uses the addition of a ________ to release the ________, which is the soap.
fats or oils; hydrolysis; strong base; deprotonated fatty acid
recommendations in case of accidental contact with the chemical
first aid measures
While checking on a stirring solution, the solution splashes up towards your face.
goggles
Changing gloves often will minimize the spread of chemicals. To properly remove gloves, first, ______, and then, __________. Then insert ________ between the interior edge of the second glove and the skin, and remove the second glove.
grasp the exterior of one glove with a gloved hand; peel off the first glove; a bare finger
incompatibility or reactivity with other chemicals
handling and storage
possible dangers and health effects
hazards identification
A flexible polymer used in the manufacturing of grocery bags. The molecular structure is (C2H4)n(CX2HX4)n .
high-density polyethylene
When a protein is _________, the bonds between amino acids are cleaved and the protein is broken down into individual amino acids. When a protein is __________, the protein loses its shape.
hydrolyzed; denatured
The purpose of the best-fit line on an experimental scatterplot is to ___________. The best-fit line allows us to__________.
identify any linear trend in scattered data; predict behavior between measured data using its slope
The synthesis of nylon requires solutions of 5% hexamethylenediamine and 5% adipoyl chloride. This polymer will form _________. To remove the nylon, __________.
in between layers of the solutions; catch on the tip of a sharp object
When testing the solubility of compounds containing -OH groups, check the solubility ________ first. If the compound is soluble under that condition, its solubility ________ does not need to be tested.
in water; in aqueous NaOH
Which substance is not a carbohydrate?
lipid
Do not use open flames, like Bunsen burners.
many organic chemicals are flammable
Use glass containers, unless instructed to do otherwise.
many organic chemicals dissolve plastics
Rinse the glassware with organic solvents after the experiment.
many organic chemicals do not dissolve in water
Perform procedures in the fume hood, if possible.
many organic chemicals involve harmful vapors
The titration of vitamin C with iodine proceeds according to the given equation. C6H8O6+I2⟶C6H6O6+2HICX6HX8OX6+IX2⟶CX6HX6OX6+2HI In this reaction, vitamin C is _______ and iodine is _______.
oxidized; reduced
Most chemicals can be cleaned up with a general spill kit, but a few chemicals require specialized spill procedures. For each substance listed, determine whether a general spill kit is sufficient or if a specialized spill kit is needed.
phosphoric acid - general acetone - general mercury - special methanol - general hydrofluoric acid - special
A polymer produced through a condensation reaction, with applications ranging from clothing to packaging.
polyethylene terephthalate
A rigid, brittle polymer used in disposable food containers. The backbone of the polymer contains phenyl rings.
polystyrene
A rigid polymer used often in construction materials. The structure contains a halogen.
polyvinyl chloride
What color is Sudan III?
red
Benedict's test shows the presence of _______.
reducing sugars
Determine the best way to deal with each of the following items that may dangle into the way during lab work. loose bracelets long necklaces flowy sleeves long hair long earrings
remove remove tie back or secure tie back or secure remove
What should you do every time before you leave the lab?
remove your gloves wash your hands remove your labcoat, if you are wearing one
Determine where to dispose of each type of waste. syringe tips unused solid reagent titrant solution broken flask
sharps container solid waster container nalgene bottle with cap box lined with puncture resistant bag
What property is used to separate DNA fragments during a gel electrophoresis experiment?
size
Move to the safety shower if you spill hazardous chemicals on your ________. Stand under the shower and ______ the lever. Remove clothing and continue flushing the area for _________.
skin or clothing; pull; 15 minutes
After the reaction of base with the fat or oil to form a soap, add a saturated solution of __________. This addition helps _______ the soap as it increases the ________ of the solution so the soap floats on top.
sodium chloride; precipitate; density
Which states of matter can be separated by gravity filtration?
solid and liquid
The purpose of a centrifuge is to separate a sample into a _________ component and a _________ component.
solid; liquid
The iodine test shows the presence of _______
starch
Which process would restore a fatty acid from a soap?
the addition of an acid
A measurement of the amount of light that passes through a sample
transmittance
Food items should not be brought into the lab.
true
Tobacco products of all kinds are prohibited in lab.
true
What is the last step of any spill cleanup procedure?
Wipe down the affected area with detergent and water
A positive iodine test appears as ______
a color change to blue-black
When testing the pH of a solution with pH or litmus paper, dip _________ in the solution. Add a ______ of the solution to the paper. Compare the ________ of the pH paper to the scale that appears on the container.
a stirring rod; drop; color
A measurement of the amount of light taken in by a sample
absorbance
A polymer formed as monomers link together without forming a byproduct.
addition polymer
What are the building blocks of proteins?
amino acids
Solution of an unknown concentration that has another solution slowly added to it
analyte
Identify the medical applications of aspirin.
anti-inflammatory agent; pain killer; anti-coagulant; fever reducer
When heating liquids in a test tube, it is important that the test tube be positioned _____, pointed _____ people, and _______.
at an angle; away from; half-full
A sample prepared using the solvent and any other chemicals in the sample solutions, but not the absorbing substance
blank
Glassware that allows a solution to be precisely and slowly added to another solution
buret
When an alarm sounds in the laboratory, it is important to respond ________ and remain _______. Listen for any other instructions, turn off any ________ in use, and be prepared to leave immediately.
calmly; quiet; equipment
Which four molecules are tested for in the lab?
carbohydrates, starch, proteins, lipids
Aspirin was formed to reduce the irritation of salicylic acid. However, aspirin can still disturb the stomach. Which functional group in aspirin is responsible for stomach irritation?
carboxylic acid
What functional groups are present in all amino acids?
carboxylic acid, amine