science
Solutions can be...
- acidic, basic (alkaline) or neutral
Whats the chemical change
- when one or more substances form
students preformed an investigation on how aluminum cans taken ti a recycle center were able to be reused. they found out an aluminum can undergoes which type of change?
a physical change because the material remains the same
Why is baking a cake a chemical reaction and not a physical one?
- because the compounds in the mixture broke down and forms a new substance with different composition
What are some examples of formation of precipitate?
- carbon dioxide combines with aqueous calcium hydroxide (limewater), solid calcium carbonate(chalk) is formed, The chalk is the precipitate, then appearance as cloudiness in the solution or solid that settles to the bottom of the container
The observation would be made if a precipitate reaction will have occurred?
- cloudy solution
Reactions occur at...
- different rates, slow or fast
The pH scale is used to describe...
- how acidic or basic a solution is
to clear solutions are mixed together in a beaker which result would indicate a chemical reaction has occurred between the three solutions - increase the volume of the beaker - Decrease the volume in the beaker - in temperature of the beaker - decrease in the solubility of the liquids
- increase in temperature of the beake
Each increase of one in the pH scale is an
- increase of 10 times the concentration.
What does temperature change mean?
- increase or decrease in temperature when substances combine
What is an example of color changes
- iron turns to reddish-brown when it rusts,apple brown when reading with oxygen in the air, marshmallows turn black when burned
what piece of knowledge would be useful to a scientist to help him or her identify a substance
- knowing the characteristic properties
In chemical changes....
- new substances are Formed and they break apart or substances combine to form new substances
the chemical reaction between oxygen in the air demonstrates which type of chemical change - precipitation - sublimation - reactivity - oxidation
- oxidation
Chemical properties of compounds include
- reactivity and flammability
What does the type of solution depend on?
- the concentration of hydrogen ions in the solution
What does formation of precipitate mean?
- two substances combine and they may form a solid substance;the solid substance is called a precipitate
What is are some examples of temperature change?
- wood burning to ash and gases-increase in temperature and hot gases formed when hydrogen and oxygen join to make water helped space shuttle into orbit
What are some examples of chemical properties?
-Color change,Temperature change, formation of Precipitate, and formation of gas
Chemical changes have....
-New chemical and physical properties
Baking soda and vinegar were mix and match was struck. Which best explains why is a lit match went out when placed in the mouth of the flask?
-The baking soda and vinegar reacted to produce carbon dioxide gas. The carbon dioxide gas cause the lit match to go out.
water is know as the ...
-Universal solvent because so many substances dissolve in it
what are some examples of formation of gas?
-adding vinegar to baking soda. it forms carbon dioxide bubbles
which the best evident that a chemical change in matter has occurred?
-an entirely new substance is formed
Reaction rates can be changed by ...
-changing the concentration of the reactants(the substances combining to cause a reaction)
What does formation of gas mean?
-solid or liquid substances combine to form gas bubbles
Rates change by changing the....
-temperature, the surface area of solids, and using a catalyst
Which best describes a physical change - change in state - formation of gas - reactivity with two or more substances - change in temperature
change in state
Chemical reactions take place in...
chemical changes
when baking soda and vinegar react, the product produces bubbles. What has most likely occurred?
gas formation
can a phase change, or change in a substances state of matter, produce new compounds?
no because physical changes occur
what chemical reaction results in the formation of gas
precipitate
in which state of matter will the atoms of an element be tightly packed together
solid
Over a few hours steel wool soaking and hydrogen peroxide in a closed container in which most of the air has been removed, changes its appearance from a bright silver to adult black. this is evidence of
the chemical change because the steel wool changed color
Many substances dissolve in...
water
