chem lab 1 mid
An example of a physical change 1.breaking a glass window 2.the formation of a solid after mixing two liquids 3.iodine solid subliming into a gas
1 & 3
An example of a physical change would be 1.evaporating fresh water into seawater 2.fireworks exploding 3.crushing a can
1 & 3
Which answer lists all the substances below that are compounds and not any elements or mixtures? 1.Sodium chloride 2.Neon 3.Sulfur 4.Water 5.Crude oil
1 & 4
An example of a chemical change is 1.burning 2.boiling 3.evaporation 4.bending 5.reacting
1 & 5
An example of a physical change is 1.burning 2.boiling 3.evaporation 4.bending 5.Reacting
2,3,4
An example of a chemical change would be 1.toasting a marshmallow 2.digesting food 3.gasoline being used in the engine of a car producing exhaust 4. all of the above
4 all of the above
Trini adds 10 grams of baking soda to 100 g of vinegar. The mixture begins to bubble. When the bubbling stops, Trini finds the mass of the resulting mixture. She determines its mass is 105 g. Why has the total mass changed?
A gas has formed and left the mixture.
A chemical change is different than a physical change because in a chemical change
A new substance is formed and in a physical change no new substance is formed.
Marco tears a piece of notebook paper into smaller pieces,Tearing paper into pieces is an example of what kind of change?
A physical change.
What lab equipment holds solids or liquids that will not release gases when reacted or are unlikely to splatter if stirred or heated?
Beaker
Which one of the following is NOT an example of a separation technique?
Boiling an egg
Which of the following shows three examples of a physical change?
Boiling of water, dissolving salt into water, and melting of an ice cube
What lab equipment is used to provide heat for experimentation?
Bunsen Burner
Which observation does NOT indicate that a chemical reaction has occurred? -Formation of a precipitate -Evolution of heat and light -Production of a gas -Change in total mass of substances.
Change in total mass of substances.
What lab equipment is used to move a crucible from the heat?
Crucible Tongs
Which of the following techniques is best suited for purifying whiskey (a blend of various liquids)?
Distillation
Which of the following physical methods may be used to separate salt water into its pure substances:
Distillation of a salt water solution.
What lab equipment is rarely used by first year chemist and is used to mix chemicals that may splatter? It has a narrow neck to prevent splatter?
Erlenmeyer Flask
What lab equipment is used for the heating of stable solid compounds and elements? Also used to separate a solid suspended in a liquid by boiling away the liquid.
Evaporating Dish
In the process of evaporation, which one of the following pieces of laboratory apparatus would NOT be used?
Filter funnel
What lab equipment holds solids or liquids that may release gases during a reaction or that are likely splatter if stirred or heated.
Florence Flask
Which of the following is accurate for calcium
Good conductor of heat and electricity, high melting point.
What lab equipment is used to measure volumes of liquid?
Graduated Cylinder
What long tube with a small diameter is used to measure and deliver exact volumes of liquids? It is designed to measure different amounts of the liquid and uses a bulb to draw the liquid into it?
Graduated Pipet
Which one of the following is a disadvantage of evaporation?
It cannot be used for insoluble solids.
A sample of matter that can be decomposed into three different elements
Must be a compound
A student watches an ice cube melt into a puddle of water. Has a chemical change occurred?
No, no new substances have formed
An example of a chemical change: 1.water freezing into ice crystals 2.after shave or perfume on your skin generating a smell 3.a piece of metal expanding when heated, but returning to original size when cooled
None of the above
Which of the following is not a mixture?
Oxygen
What lab equipment is used to safely and conveniently perform reactions that require heating using a Bunsen Burner?
Ring Stand
What lab equipment is used to manually stir solutions?
Stirring Rod
When oxygen is available, sulfur dioxide is produced from the burning of sulfur. Which of the following word equations best represents this reaction?
Sulfur + oxygen → sulfur dioxide.
What lab equipment is used for holding and organizing test tubes on the laboratory counter? Also a good place to store test tubes while they dry.
Test Tube Rack
In a chemical change
The atoms of the reactants unbond, rearrange, and then rebond to form the products.
Which piece of laboratory equipment can be used to store chemicals for long periods of time?
The evaporating dish and beaker are suitable for storing some chemicals.
A chemical reaction has NOT occurred if the products have
The same chemical properties as the reactants.
One clue of a chemical change is the formation of a precipitate. A precipitate is formed when
Two liquids react and a solid is formed.
Which of the following is NOT an element? Water,Hydrogen,oxygen,Sodium, calcium
Water
Which of the following pairs of substances may best be separated through distillation?
Water and alcohol
What lab equipment is used to collect large amounts of gas and is done so by the displacement of water?
Wide Mouthed Bottle
A piece of equipment which would be used to measure volume is:
a graduated cylinder
I crush crystals of calcium carbonate into a fine powder in a mortar and pestle. This is an example of
a physical change
Which of the following is a physical change? a.The condensation of water vapor onto a window. b.The formation of carbon dioxide and water after combustion. c.The aging of a half-eaten apple resulting in a brown color. d.The formation of smoke after burning a match. e. The reaction between hydrogen and oxygen to form water.
a.The condensation of water vapor onto a window.
To dilute a concentrated acid:
add acid to the water.
Goggles should be worn:
all the time during lab.
If you do not understand the experimental procedure:
ask the instructor.
You should always hold containers that have chemicals:
away from your body.
Which of the following is a physical change? a.The formation of ash when burning wood. b. The vaporization of solid carbon dioxide (dry ice). c.The formation of rust on metal tools left out in the rain. d.The formation of bubbles when grapes are fermenting. e.The aging of an egg with a resultant unpleasant smell.
b.The vaporization of solid carbon dioxide (dry ice).
Weighing out 120 grams of sodium chloride:
balance
In the lab each student should:
be on alert, watching for his own safety and the safety of others .
Holding 50 mL of boiling water:
beaker
. If you spill solid chemicals on a balance:
brush off any spills.
Since you cannot tell from the appearance of a metal or glass that it is still hot, you should test it by:
cautiously bringing the back of your hand close to the hot glass or metal.
When a piece of magnesium ribbon is burned it forms a bright light and a gray ash. This is an example of a
chemical change
When copper chloride and aluminum are combined together, aluminum chloride and copper form. This is an example of a
chemical change
Substances may be described by a variety of types of properties. What type of property describes the tendency of a substance to be transformed into a different substance?
chemical property
Melting a crystal over a Bunsen Burner:
crucible and cover
A solid produced by a chemical reaction in solution that separates from the solution is called
d. The mass of the product
An unused/leftover chemical should be:
disposed of in the designated waste container.
Wash bottles should be filled 'only' with
distilled or de-ionized water.
To weigh 2 grams of salt in lab: a) place salt into a beaker before weighing it on the balance. b) place salt directly on the balance to avoid contamination. c) do not use a balance and just eye-ball a sample that may look to be about 2 grams d) mix the salt with water before weighing it on the balance. e) none of the above.
e) none of the above.
You may leave a lighted Bunsen burner unattended only, if: a) you must go to the restroom. b) your neighbor keeps an eye on it. c) no one else is in the class but you. d) you need to go to the reagent bench to quickly get more chemicals e) none of the above.
e) none of the above.
When heating liquid in test tube, the open end of the test tube: a) should point towards you. b) should be pointing at an angle that allows the liquid to splash gently over the hot glass, but not out of the test tube. c) should point towards the person across the lab bench from you since they are far enough away. d) should be covered with a stopper or cork to avoid contamination. e) none of the above.
e)none of the above.
Which of the following is categorized as a pure substance? Element,Colloid,solution, Mixture,suspension
element
Which of the following is made of only one type of atom?
element
Mixing two liquids together:
erlenmeyer flask
The separation technique that involves heating a solution until the liquid changes into a gaseous state is
evaporating
If you are instructed to smell a chemical in the lab, you need to:
fan the air above the chemical toward your nose.
Measuring exactly 43 mL of water:
graduated cylinder
Pouring 50 mL of acid from one container to another:
graduated cylinder
What piece of laboratory equipment is best-suited for accurately measuring the volume of a liquid?
graduated cylinder
Which one of the following would NOT be used to boil water:
graduated cylinder
Johnny adds liquid chocolate syrup to milk and stirs well. He obtains one solution with uniform composition, chocolate milk. How would it be classified?
homogeneous mixture
Store chemicals in:
labeled containers.
Lucy was using the triple beam balance during an experiment. She was measuring :
mass
dependent variable
measured quantity
Two or more substances combined together without changing properties results in a
mixture
A cracked test tube or chipped glassware should:
never be used.
Which of the following would be categorized as a heterogeneous mixture? CaCO3 brass alloy alcohol
none
Stamping or pressing gold into a coin is an example of a
physical change
When a solid changes to a liquid or a liquid changes to a gas, it is changing state. This is an example of a
physical change
A characteristic that is observed without changing the substance.
physical property
To remove liquid from a reagent bottle:
pour some liquid directly into your container.
You should prepare for the lab by:
reading the assigned experiment before coming to the lab.
After dispensing a chemical from a container:
replace the stopper immediately.
Removing dry chemicals from a reagent bottle:
scoopula
A small amount of sugar was poured into water and was stirred to mix the sugar evenly in the water. How many of the following accurately describe the liquid?
solution
To dispense a required amount of reagent:
take your container to the reagent bench.
Suspending a test tube over a Bunsen burner:
test tube holder
Before using the contents of a bottle, check:
the label on the bottle.
You must wear goggles in the lab because:
they protect your eyes from chemical splashes.
Suspending a beaker over a Bunsen burner:
tripod and wire gauze
To handle hot objects like a beaker or evaporating dish:
use a pair of tongs.
To add water to a reagent used in an experiment
use distilled or de-ionized water.
To remove solid chemicals from a bottle:
use your spatula to remove the solid.
If you need to touch or rub your eyes, you must
wash your hands.
Keeping the contents of a boiling beaker from splattering:
watch glass
A hot object, like an evaporating dish or crucible, is allowed to cool by placing it on
wire gauze.
Pick up a reagent bottle by holding it:
with your palm over the label.
To light a Bunsen burner
you need to step back.
