Docstoc

Lab: Physical & Chemical Changes

Document Sample
Lab: Physical & Chemical Changes Powered By Docstoc
					                                                                                Lab 2 Write-Up
                                                                                         Per: 3
                            Physical and Chemical Change
Purpose: The purpose of this experiment was to observe and receive a stronger understanding of
whether certain changes are physical changes or chemical changes.

Procedure: See Attached

Data and Observations:

Table 2.1 Data Table for Part A
Substance and     Physical      Color              Odor         Solubility in    Effect of
Formula           State                                         Water            Magnet
Sulfur, S         Solid Powder Seems to be         Seems to     No solubility    None
                                Solid pale         smell like
                                yellow             rotten
                                                   eggs.
Iron Fillings, Fe   Rough solid     Seems to be    Seems to     No solubility    Attracted by
                    powder          Silver-Gray    smell                         metal
                                                   metallic
                                                   with very
                                                   light odor
Sodium Hydrogen     Crystalline     Seems to be    Seems to     Soluble in       None
Carbonate,          powder          White          have no      water
NaHCO3                                             odor
Sodium Chloride,    Crystalline     Seems to be    Seems to     No solubility    None
NaCl                solid powder    White          have no
                                                   odor
Sucrose,            Solid Crystal   Seems to be    Seems to     Soluble in       None
C12H22O11           Powder          White          have no      water
                                                   odor
Sand, SiO2          Solid Grains    Seems to be    Seems to     No solubility    None
                                    Gray-Brown     have no
                                                   odor
Magnesium, Mg       Solid Strip     Seems to be    Seems to     No solubility    None
                                    Silver         have no
                                                   odor


Table 2.2 Data Table for Parts B and C
System           Type of Change              Evidence (Observations)
Fe and S mixture Physical                    The two substances seem to be physically mixed
                                             but it could be easily reversed by using a magnet
                                             to attract iron and the color of each substance
                                             remain the same so the two mixtures keep their
                              identity.
NaCl and Sand      Physical   It is a physical change because the two substances
mixture                       keep its identity because the color of each
                              substance is the same and the mixture of these
                              two substances could be reversed by using
                              filtration because salt dissolves and sand doesn’t.
Sand and Water     Physical   It is a physical change because sand is not
mixture                       chemically mixed with water, instead it seems
                              more physically mixed and it can be easily
                              reversed by using filtration, which separates it
                              from the water. The two substances also keep
                              their identity because the colors of the two remain
                              the same and nothing seems to change about
                              them.
Mg burned in air   Chemical   It is a chemical change because the magnesium
                              ribbon changes its identity when it turned to a
                              twisted solid that seemed to be white instead of
                              what it used to be which was a silver strip.
Mg reacted w/      Chemical   It is a chemical change because the magnesium
HC1                           seemed to mix with the hydrochloric acid to form
                              a liquid that seemed to be yellowish white. The
                              magnesium change its identity when it change
                              color and seemed to change temperatures from
                              room temperature to hot.
Burned Mg w/       Chemical   It is a chemical change because the combustion
HC1                           product and hydrochloric acid seemed to mix to
                              form a liquid that seemed to be clear water and a
                              solid that seemed to be powder.
Sucrose heated     Chemical   It is a chemical change because the sucrose
                              changes to a color that seems to be brownish-
                              black and the substance seems to take up more
                              space in the test tube. There also seems to be a
                              new smell to the substance that seems to sell like
                              marshmallows.
NaHCO3 and         Chemical   It is a chemical change because the sodium
HC1                           hydrogen carbonate mixes with the hydrochloric
                              acid that causes it to fizz and the water seems to
                              be clear. There is an acid and a base in this
                              mixture that forms a new substance which makes
                              it a chemical change.
Fe and S heated    Chemical   It is a chemical change because the substance
                              changes its identity when it seems to turn to a
                              dark brown color that no longer has a response to
                              the magnet. There also seems to be a new smell
                              after burning that seems to smell like rotten eggs.
Mixture                             Initial Mass                   Final Mass
Sulfur (S) and Iron Fillings (Fe)   39.61 grams                    39.59 grams


Data Analysis:

   1. How do you decide whether and observed property of matter is a physical or
      chemical property?
      Physical properties are the characteristics that can be observed without changing the
      substance into another substance. Chemical properties are the characteristics that can be
      observed when the substance undergoes a change in its composition.

   2. What criteria are used to distinguish between a chemical change and physical
      change?
      A physical change is a reversible change that involves the substance keeping its identity
      while a chemical change is an irreversible change that involves the substance changing its
      identity to something new.

   3. State in your own words the law of conservation of mass.
      The law of conservation of mass states that matter cannot be formed or destroyed but it
      can change its state to other forms in a closed system.

Conclusion: This lab of physical and chemical changes has achieved its goal because it has
helped me better understand the chemical and physical properties as well as the type of change of
certain substances. It showed how physical changes are reversible changes that keep its identity
while chemical changes are irreversible changes that changes to a different substance. Parts of
the lab like the heating of the mixture of sulfur and iron fillings helped show me that this was a
chemical change what was irreversible because you cannot return it to two separate substances
again. Other parts such as the mixture of sand and water showed me that it was a physical change
because the sand physically mixed with water and it could be reversed with filtration, which is
the difference in solubility that separates the sand from the water. All in all, this lab helped my
understanding of the differences in chemical and physical changes.

				
DOCUMENT INFO
Shared By:
Stats:
views:321
posted:1/23/2011
language:Italian
pages:3
Description: Use this as a guide on how you should write you lab 2 writeup for physical and chemical changes