SNC1D – Chemical Changes – How Can We Tell?

Introduction Different types of matter have different types of properties. Many of these properties are different becauseof different arrangement of electrons and different masses. Both of these will be discussed in detail whenwe examine the structure of atoms and the arrangement of the periodic table.

A chemical change requires the rearrangement of matter. How do we know if a chemical change hasoccurred? We observe the formation of new substances with new physical properties orobserve for changes in energy.

Therefore observe for substances that were not there before and temperature changes.

Tasks:

For the following situations you must: [A5]

create a data table to record observations. observe the substances before. during and afterrecord observations using excellent science adjectives already learned to describe physical propertiesfrom previous lesson. [IE> lustre, malleable, brittle, etc]

The following situations may be performed in any order. You may want to start at the bottom to preventdemand for limited supplies.

Situation 1: Metals in acids

using a couple of test tubes, place a small piece of magnesium [Mg] into ~5mLs of hydrochloric acid[HCl].perform the same situation but replace magnesium [Mg] with copper [Cu].

Situation 2: burning of magnesium

using a SMALL piece of magnesium held using a set of crucible tongs, light a bunsen burner, place the end of the magnesium in the hottest part of the flame [tip of inner flame]

Situation 3: displacement of copper

using a test tube, dissolve a small scoop of copper (II) sulphate [CuSO4] into ~10 mLs of waterplace a small piece of "steel wool" , this is iron [Fe], into the dissolved copper (II) sulphate.

Situation 4: formation of a salt

using a test tube, place a small amount of granular zinc into ~10mLs of water.scoop a small amount of solid iodine into the water and stir using a stirring rod.save the liquid portion of this reaction for situation 5

Situation 5: formation of pure elements using electricity

decant, [ask Mr. L if you don't know what this means] the liquid from situation 4 into a SMALL beaker.using a battery and two pieces of wire, create a small circuit THROUGH the liquid in the beaker.

Situation 6: dissolving of salts

using a test tube, scoop a small amount of sodium chloride into ~5 mLs of waterin a separate test tube, scoop a small amount of urea into ~5 mls of water.

Situation 7: formation of a solid precipitate

using a spot plate, mix a few drops of lead (II) nitrate [Pb(NO3)2] and a few drops of potassium iodide[KI].

Analysis:

state and explain, using the evidence of your observations, which situations demonstrated changesof a chemical nature.

1.