Riah​ ​Kim

Ms.​ ​Rebancos
DP​ ​Chemistry​ ​11
31​ ​October​ ​2017
Determining​ ​the​ ​Formula​ ​of​ ​Hydrated​ ​Copper(II)​ ​Sulfate
Aim:
The​ ​aim​ ​of​ ​this​ ​lab​ ​is​ ​to​ ​determine​ ​the​ ​formula​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​by​ ​determining​ ​the
number​ ​of​ ​moles​ ​of​ ​water​ ​of​ ​crystallization​ ​in​ ​crystals​ ​of​ ​a​ ​hydrated​ ​salt​ ​CuSO4·xH2O​ ​by
heating​ ​it​ ​to​ ​constant​ ​mass​ ​in​ ​a​ ​crucible.

Research​ ​Question:
What​ ​is​ ​the​ ​effect​ ​of​ ​the​ ​mass​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​on​ ​the​ ​mass​ ​of​ ​water​ ​lost​ ​during​ ​the
decomposition​ ​process​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​measured​ ​in​ ​grams( ± 0.01 g)​ ​when​ ​the
heating​ ​temperature(same​ ​burner,​ ​same​ ​heating​ ​power),​ ​the​ ​crucible​ ​are​ ​kept​ ​constant​ ​and​ ​for
each​ ​trial​ ​the​ ​crystal​ ​had​ ​enough​ ​time​ ​to​ ​be​ ​fully​ ​decomposed?

Hypothesis:
If​ ​the​ ​mass​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​increases,​ ​then​ ​the​ ​mass​ ​of​ ​water​ ​lost​ ​during​ ​the
decomposition​ ​process​ ​would​ ​increase​ ​as​ ​well,​ ​due​ ​to​ ​the​ ​law​ ​of​ ​definite​ ​proportions.

Background:
A​ ​hydrate​ ​is​ ​a​ ​compound​ ​that​ ​contains​ ​H​2​O.​ ​It​ ​is​ ​usually​ ​in​ ​the​ ​form​ ​of​ ​a​ ​crystal​ ​that​ ​can
be​ ​heated,​ ​and​ ​this​ ​means​ ​that​ ​the​ ​crystals​ ​contain​ ​water​ ​molecules​ ​within​ ​their​ ​structure​ ​in
definite​ ​proportions.​ ​And​ ​the​ ​water​ ​here,​ ​also​ ​known​ ​as​ ​water​ ​of​ ​crystallization,​ ​can​ ​be​ ​lost​ ​by
turning​ ​into​ ​steam.​ ​This​ ​usually​ ​causes​ ​the​ ​hydrate​ ​to​ ​lose​ ​its​ ​crystalline​ ​structure.​ ​The​ ​substance
that​ ​is​ ​left​ ​over​ ​after​ ​the​ ​hydrate​ ​has​ ​lost​ ​its​ ​water​ ​is​ ​called​ ​an​ ​anhydrate​.​ ​By​ ​measuring​ ​the
compound​ ​before​ ​heating​ ​and​ ​after,​ ​the​ ​amount​ ​of​ ​water​ ​in​ ​the​ ​original​ ​hydrate​ ​can​ ​be
determined​ ​and​ ​the​ ​formula​ ​can​ ​be​ ​discovered.​​ ​The​ ​formula​ ​for​ ​the​ ​crystal​ ​shows​ ​the​ ​number​ ​of
water​ ​molecules​ ​present​ ​per​ ​formula​ ​unit​ ​of​ ​crystal,​ ​and​ ​a​ ​dot​ ​is​ ​put​ ​before​ ​the​ ​water.
Substances​ ​that​ ​absorb​ ​water​ ​from​ ​the​ ​air​ ​to​ ​form​ ​hydrates​ ​are​ ​called​ ​deliquescent.
Hydrates​ ​that​ ​lose​ ​water​ ​of​ ​crystallization​ ​to​ ​form​ ​the​ ​anhydrous​ ​substances​ ​are​ ​called
efflorescent.​(“Hydrate​ ​|​ ​Chemical​ ​Compound”)​​ ​Usually​ ​the​ ​uptake​ ​and​ ​loss​ ​of​ ​water​ ​are
reversible​ ​processes,​ ​and​ ​sometimes​ ​these​ ​processes​ ​result​ ​in​ ​changes​ ​in​ ​colour.​ ​For​ ​example,
copper​ ​sulfate​ ​pentahydrate​ ​(CuSO​4​·5H​2​O)​ ​is​ ​blue​ ​and​ ​anhydrous​ ​copper​ ​sulfate​ ​(CuSO​4​)​ ​is
white.
 As​ ​mentioned​ ​in​ ​the​ ​previous​ ​paragraph,​ ​the​ ​reaction​ ​between​ ​anhydrous​ ​copper​ ​sulfate
and​ ​water​ ​is​ ​reversible:​ ​water​ ​is​ ​driven​ ​off​ ​from​ ​hydrated​ ​copper​ ​sulfate​ ​when​ ​heated,​ ​so​ ​the
forward​ ​reaction​ ​is​ ​endothermic;​ ​energy​ ​is​ ​transferred​ ​from​​ ​the​ ​surroundings.​ ​The​ ​backward
reaction​ ​is​ ​called​ ​exothermic;​ ​energy​ ​is​ ​transferred​ ​to​​ ​the​ ​surroundings.​(“BBC​ ​-​ ​GCSE​ ​Bitesize:
Reversible​ ​Reactions”)

Variables:

Variable Units​ ​& How​ ​are​ ​they​ ​manipulated?

Uncertainties

Independent mass​ ​of​ ​hydrated g​ ​( ± 0.01 g) I​ ​will​ ​put​ ​in​ ​different​ ​amount​ ​of
copper(II)​ ​sulfate hydrated​ ​copper(II)​ ​sulfate​ ​for​ ​each
sample.

Dependent mass​ ​of​ ​water​ ​lost g​ ​( ± 0.01 g) Not​ ​manipulated​ ​-​ ​depends​ ​on​ ​the
mass​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate.

Controls Heating °​C I​ ​will​ ​use​ ​the​ ​same​ ​Bunsen​ ​burner

temperature and​ ​the​ ​heating​ ​power(strength).

Crucible No​ ​unit I​ ​will​ ​use​ ​the​ ​same​ ​crucible​ ​with​ ​the
same​ ​mass​ ​and​ ​thickness​ ​-​ ​so​ ​the
thickness​ ​of​ ​the​ ​crucible​ ​doesn’t
affect​ ​the​ ​heating​ ​time.

Materials:

Item Quantity Size Unit​ ​of​ ​measurement​ ​&

Used Uncertainty

Crucible 1 15​ ​mL No​ ​unit

Hydrated​ ​copper(II) Between No​ ​size g,​ ​ ± 0.01 g

sulfate 2.00​ ​g​ ​and
3.00​ ​g

Balance(Scale) 1 No​ ​size g,​ ​ ± 0.01 g

Ring​ ​stand 1 50​ ​cm No​ ​unit

Pipe-clay​ ​triangle 1 No​ ​size No​ ​unit

Bunsen​ ​burner 1 No​ ​size No​ ​unit

 Ring​ ​clamp 1 No​ ​size No​ ​unit

Matches 5 No​ ​size No​ ​unit

Crucible​ ​Tongs 1 No​ ​size No​ ​unit

Scoopula 1 No​ ​size No​ ​unit

Procedure:
1. The​ ​empty​ ​crucible​ ​was​ ​weighed,​ ​and​ ​then​ ​between​ ​2.00​ ​g​ ​and​ ​3.00​ ​g​ ​of​ ​hydrated
copper(II)​ ​sulfate​ ​was​ ​weighed​ ​and​ ​added.​ ​All​ ​masses​ ​were​ ​recorded​ ​accurate​ ​to​ ​the
nearest​ ​0.01​ ​g.
2. The​ ​crucible​ ​was​ ​placed​ ​on​ ​the​ ​pipe-clay​ ​triangle​ ​on​ ​the​ ​ring​ ​clamp​ ​fixed​ ​to​ ​the​ ​ring
stand,​ ​over​ ​the​ ​Bunsen​ ​burner.

3. The​ ​crucible​ ​and​ ​contents​ ​were​ ​heated​ ​over​ ​a​ ​medium​ ​Bunsen​ ​flame​ ​so​ ​that​ ​the​ ​water​ ​of
crystallisation​ ​is​ ​driven​ ​off​ ​steadily.​ ​The​ ​blue​ ​colour​ ​of​ ​the​ ​hydrated​ ​compound​ ​was
gradually​ ​faded​ ​to​ ​the​ ​greyish-white​ ​of​ ​anhydrous​ ​copper(II)​ ​sulfate.​ ​Overheating
should​ ​have​ ​been​ ​avoided​ ​since​ ​it​ ​might​ ​have​ ​caused​ ​further​ ​decomposition,​ ​and​ ​the
heating​ ​should​ ​have​ ​stopped​ ​immediately​ ​when​ ​the​ ​colour​ ​starts​ ​to​ ​blacken.​ ​If
overheated,​ ​toxic​ ​or​ ​corrosive​ ​fumes​ ​might​ ​have​ ​been​ ​evolved​.
4. The​ ​crucible​ ​and​ ​contents​ ​were​ ​cooled.​ ​The​ ​crucible​ ​and​ ​contents​ ​were​ ​re-weighed​ ​once
cold.
5. Steps​ ​3​ ​and​ ​4​ ​were​ ​repeated​ ​until​ ​it​ ​was​ ​heated​ ​to​ ​constant​ ​mass​ ​and​ ​consistent​ ​readings
were​ ​being​ ​gathered.

Safety,​ ​Environmental​ ​&​ ​Ethical​ ​Considerations:

Potential​ ​harm​ ​that​ ​could​ ​have​ ​arisen​ ​from​ ​this​ ​experiment​ ​was​ ​something​ ​with​ ​Bunsen
burner​ ​and​ ​fire.​ ​During​ ​the​ ​experiment,​ ​the​ ​too​ ​much​ ​gas​ ​came​ ​out​ ​from​ ​the​ ​hose​ ​and​ ​the​ ​fire​ ​got
so​ ​big​ ​a​ ​few​ ​times.​ ​No​ ​one​ ​was​ ​hurt,​ ​but​ ​it​ ​was​ ​big​ ​enough​ ​to​ ​scare​ ​or​ ​shock​ ​someone,​ ​which
could​ ​have​ ​led​ ​to​ ​other​ ​possible​ ​accidents.​ ​A​ ​person​ ​could​ ​have​ ​fallen,​ ​and​ ​if​ ​the​ ​person​ ​was
holding​ ​a​ ​crucible,​ ​that​ ​crucible​ ​would​ ​have​ ​been​ ​broken​ ​and​ ​that​ ​could​ ​have​ ​hurt​ ​someone.​ ​But
this​ ​risk​ ​was​ ​minimized​ ​by​ ​being​ ​more​ ​careful​ ​when​ ​turning​ ​on​ ​the​ ​gas.​ ​Instead​ ​of​ ​turning​ ​the
lever​ ​quickly,​ ​we​ ​tried​ ​to​ ​turn​ ​it​ ​slowly​ ​while​ ​looking​ ​at​ ​the​ ​flame​ ​so​ ​we​ ​could​ ​stop​ ​turning​ ​the
lever​ ​when​ ​the​ ​size​ ​of​ ​the​ ​flame​ ​was​ ​adequate.
One​ ​toxic​ ​or​ ​potential​ ​harm​ ​for​ ​the​ ​environment​ ​was​ ​a​ ​possible​ ​toxic​ ​fumes​ ​that​ ​might
have​ ​been​ ​evolved​ ​from​ ​overheating​ ​hydrated​ ​copper(II)​ ​sulfate.​ ​In​ ​order​ ​to​ ​prevent​ ​this,​ ​I​ ​made
sure​ ​that​ ​I​ ​was​ ​not​ ​overheating​ ​the​ ​compound.

Raw​ ​Data​ ​Table:

Mass​ ​(grams)​ ​(±0.01​ ​g) Observations

Mass​ ​of​ ​crucible​ ​+​ ​lid 38.04

Mass​ ​of​ ​crucible​ ​+​ ​lid​ ​+

CuSO​4 · xH​2​O​ ​before​ ​heating 40.36 It​ ​was​ ​solid;​ ​blue​ ​crystal

Trial​ ​1 39.51
Mass​ ​of​ ​crucible​ ​+​ ​lid​ ​+ It​ ​was​ ​greyish​ ​white,​ ​and​ ​some
CuSO​4​(anhydrous)​ ​after​ ​heating Trial​ ​2 39.51 blueish​ ​white​ ​were​ ​also​ ​visible.

Uncertainty​ ​Calculation:
-​ ​ 0.01 ÷ 2.32 = 0.004 g

Processed​ ​Data​ ​Table:

Mass​ ​(g,​ ​ ± 0.01 g) Uncertainty​ ​(g)

CuSO​4​·xH​2​O 2.32 0.004

CuSO​4 1.47 0.007

H​2​O​ ​lost​ ​after​ ​heating 0.85 0.012

Calculations:
-​ ​Mass​ ​of​ ​CuSO​4​·XH​2​O
-​ ​ 40.36 − 38.04 = 2.32 g
-​ ​Mass​ ​of​ ​CuSO​4
-​ ​ 39.51 − 28.04 = 1.47 g
-​ ​Mass​ ​of​ ​water​ ​lost​ ​after​ ​heating
-​ ​ 40.36 − 39.51 = 0.85 g

1. Calculate​ ​the​ ​molar​ ​masses​ ​of​ ​H​2​O​ ​and​ ​CuSO​4​ (Relative​ ​atomic​ ​masses:​ ​H=1.01,
O=16.00,​ ​S=32.06,​ ​Cu=63.55).
a. H​2​O:​ ​ 2(1.01) + 16.00 = 18.02 (g​ ​mol​-1​)
b. CuSO​4​:​ ​ 63.55 + 32.06 + 4(16.00) = 159.61 (g​ ​mol​-1​)
2. Calculate​ ​the​ ​mass​ ​of​ ​water​ ​driven​ ​off,​ ​and​ ​the​ ​mass​ ​of​ ​anhydrous​ ​copper(II)​ ​sulfate
formed​ ​in​ ​your​ ​experiment.
a. Mass​ ​of​ ​water​ ​driven​ ​off:​ ​0.85​ ​g
b. Mass​ ​of​ ​anhydrous​ ​copper(II)​ ​sulfate:​ ​1.47​ ​g
3. Calculate​ ​the​ ​number​ ​of​ ​moles​ ​of​ ​anhydrous​ ​copper(II)​ ​sulfate​ ​formed
a. 1.47​ ​/​ ​159.61​ ​=​ ​0.00921​ ​mol
4. Calculate​ ​the​ ​number​ ​of​ ​moles​ ​of​ ​water​ ​driven​ ​off.
a. 0.85​ ​/​ ​18.02​ ​=​ ​0.0472​ ​mol
5. Calculate​ ​how​ ​many​ ​moles​ ​of​ ​water​ ​would​ ​have​ ​been​ ​driven​ ​off​ ​if​ ​one​ ​mole​ ​of
anhydrous​ ​copper(II)​ ​sulfate​ ​had​ ​been​ ​formed.
a. 0.00921 : 0.0472 = 1 : x
0.0472 = 0.00921 · x
0.0472 ÷ 0.00921 = x
x = 5.12
5.12​ ​moles​ ​of​ ​water​ ​would​ ​have​ ​been​ ​driven​ ​off.
6. Determine​ ​the​ ​formula​ ​for​ ​hydrated​ ​copper(II)​ ​sulfate.
a. CuSO​4 · 5.12H​2​O​ ​ ≈ ​ ​CuSO​4 · 5H​2​O

Percentage​ ​error​ ​calculation:

-​ ​ 5.12−5
5
· 100% = 2.4%
Conclusion:

My​ ​research​ ​question​ ​was​ ​what​ ​the​ ​effect​ ​of​ ​the​ ​mass​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​on
the​ ​mass​ ​of​ ​water​ ​lost​ ​during​ ​the​ ​decomposition​ ​process​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate
measured​ ​in​ ​grams( ± 0.01 g)​ ​is​ ​when​ ​the​ ​heating​ ​temperature(same​ ​burner,​ ​same​ ​heating
power),​ ​the​ ​crucible​ ​are​ ​kept​ ​constant​ ​and​ ​for​ ​each​ ​trial​ ​the​ ​crystal​ ​had​ ​enough​ ​time​ ​to​ ​be​ ​fully
decomposed.​ ​My​ ​hypothesis​ ​was​ ​that​ ​if​ ​the​ ​mass​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​increases,​ ​then
the​ ​mass​ ​of​ ​water​ ​lost​ ​during​ ​the​ ​decomposition​ ​process​ ​would​ ​increase​ ​as​ ​well,​ ​due​ ​to​ ​the​ ​law
of​ ​definite​ ​proportions.​ ​My​ ​hypothesis​ ​was​ ​not​ ​so​ ​supported​ ​with​ ​the​ ​data​ ​I​ ​currently​ ​have,
since​ ​I​ ​have​ ​only​ ​done​ ​one​ ​trial.​ ​But​ ​theoretically​,​ ​my​ ​hypothesis​ ​to​ ​the​ ​research​ ​question
would​ ​be​ ​supported​ ​due​ ​to​ ​the​ ​law​ ​of​ ​definite​ ​proportions​.​ ​The​ ​Law​ ​of​ ​Definite​ ​Proportions​ ​is
a​ ​rule​ ​that​ ​states​ ​that​ ​a​ ​hydrate​ ​always​ ​contains​ ​the​ ​same​ ​exact​ ​proportion​ ​of​ ​salt​ ​and​ ​water​ ​by
mass(Law​ ​of​ ​definite​ ​proportions​ ​|​ ​Chemistry).​ ​ ​For​ ​this​ ​experiment,​ ​I​ ​only​ ​did​ ​one​ ​trial​ ​using
2.32​ ​grams​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate.​ ​According​ ​to​ ​the​ ​data​ ​that​ ​I​ ​gathered,​ ​hydrated
copper(II)​ ​sulfate​ ​weighed​ ​less​ ​after​ ​the​ ​decomposition,​ ​becoming​ ​anhydrous​ ​copper(II)​ ​sulfate.
Before​ ​the​ ​heating​ ​process,​ ​CuSO​4​·xH​2​O​ ​without​ ​the​ ​crucible​ ​weighed​ ​2.32​ ​g,​ ​and​ ​after​ ​the
reaction,​ ​CuSO​4​​ ​weighed​ ​1.47​ ​g.​ ​This​ ​means​ ​that​ ​0.86​ ​g​ ​of​ ​water​ ​was​ ​“burned​ ​off”​ ​after​ ​the
decomposition.​ ​So​ ​the​ ​conclusion​ ​that​ ​can​ ​be​ ​drawn​ ​from​ ​this​ ​experiment​ ​would​ ​be​ ​that​ ​water
was​ ​lost​ ​after​ ​the​ ​decomposition​ ​due​ ​to​ ​the​ ​heat,​ ​resulting​ ​in​ ​the​ ​loss​ ​of​ ​mass.

Evaluation:

After​ ​calculating​ ​the​ ​number​ ​of​ ​moles​ ​of​ ​anhydrous​ ​copper(II)​ ​sulfate​ ​formed​ ​and​ ​the
number​ ​of​ ​moles​ ​of​ ​water​ ​driven​ ​off,​ ​I​ ​was​ ​able​ ​to​ ​calculate​ ​how​ ​many​ ​moles​ ​of​ ​water​ ​would
have​ ​been​ ​driven​ ​off​ ​if​ ​one​ ​mole​ ​of​ ​anhydrous​ ​copper(II)​ ​sulfate​ ​had​ ​been​ ​formed.​ ​The​ ​result​ ​I
got​ ​from​ ​this​ ​would​ ​be​ ​the​ ​value​ ​of​ ​coefficient(x)​ ​in​ ​CuSO​4​·xH​2​O.​ ​The​ ​number​ ​that​ ​I​ ​got​ ​was
5.12,​ ​meaning​ ​that​ ​5.12​ ​moles​ ​of​ ​water​ ​would​ ​have​ ​driven​ ​off.​ ​So​ ​my​ ​final​ ​formula​ ​would​ ​be
CuSO​4​·5.12H​2​O.​ ​If​ ​I​ ​round​ ​it​ ​off​ ​to​ ​one​ ​significant​ ​figure,​ ​it​ ​would​ ​be​ ​approximately
CuSO​4​·5H​2​O,​ ​which​ ​is​ ​the​ ​correct​ ​formula​ ​for​ ​copper(II)​ ​sulfate​ ​pentahydrate​(Pubchem)​.​ ​Even
though​ ​the​ ​value​ ​is​ ​approximately​ ​the​ ​same​ ​as​ ​the​ ​theoretical​ ​value,​ ​there​ ​still​ ​is​ ​an​ ​error​ ​range
of​ ​0.12​ ​moles.

When​ ​I​ ​calculated​ ​my​ ​percentage​ ​error,​ ​I​ ​got​ ​2.4%.​ ​By​ ​looking​ ​at​ ​this,​ ​I​ ​would​ ​conclude
that​ ​my​ ​data​ ​were​ ​accurate.​ ​The​ ​reason​ ​why​ ​the​ ​percentage​ ​error​ ​was​ ​not​ ​0%​ ​would​ ​be​ ​because
some​ ​of​ ​the​ ​crystal​ ​might​ ​have​ ​been​ ​removed​ ​or​ ​added​ ​when​ ​it​ ​was​ ​stirred,​ ​to​ ​break​ ​down
small​ ​clods,​ ​by​ ​a​ ​wooden​ ​stick.​ ​Some​ ​crystals​ ​could​ ​have​ ​stuck​ ​to​ ​the​ ​stick​ ​and​ ​therefore
removed​ ​from​ ​the​ ​crucible,​ ​and​ ​those​ ​removed​ ​crystals​ ​might​ ​have​ ​been​ ​re-added​ ​to​ ​the
crystals​ ​in​ ​the​ ​crucible​ ​later​ ​when​ ​it​ ​was​ ​stirred​ ​again,​ ​making​ ​the​ ​mass​ ​not​ ​constant.​ ​The
uncertainty​ ​values​ ​of​ ​CuSO​4​·XH​2​O,​ ​CuSO​4​​ ​and​ ​H​2​O​ ​lost​ ​after​ ​heating​ ​were​ ​0.004g,​ ​0.007g,
and​ ​0.012g.​ ​The​ ​values​ ​are​ ​generally​ ​low,​ ​which​ ​make​ ​my​ ​data​ ​highly​ ​credible.

The​ ​strength​ ​of​ ​my​ ​investigation​ ​was​ ​that​ ​when​ ​I​ ​measured​ ​the​ ​mass​ ​of​ ​the​ ​crystal​ ​twice,
I​ ​got​ ​the​ ​same​ ​value,​ ​39.51​ ​g,​ ​for​ ​both,​ ​meaning​ ​the​ ​hydrated​ ​copper(II)​ ​sulfate​ ​was​ ​fully
decomposed​ ​and​ ​H​2​O​ ​was​ ​evaporated​ ​fully.​ ​Another​ ​strength​ ​could​ ​be​ ​that​ ​I​ ​have​ ​a​ ​low
percentage​ ​error​ ​of​ ​2.4%,​ ​which​ ​means​ ​that​ ​this​ ​experiment​ ​was​ ​pretty​ ​successful​ ​and​ ​that​ ​the
procedures​ ​I​ ​used​ ​are​ ​reliable​ ​and​ ​approvable.​ ​One​ ​limitation​ ​would​ ​be​ ​that​ ​the​ ​strength​ ​of​ ​fire
was​ ​not​ ​consistent.​ ​The​ ​fire​ ​kept​ ​dying​ ​out​ ​so​ ​we​ ​had​ ​to​ ​light​ ​the​ ​fire​ ​again​ ​several​ ​times,​ ​and
even​ ​when​ ​we​ ​lighted​ ​successfully,​ ​it​ ​was​ ​hard​ ​to​ ​adjust​ ​the​ ​level/strength​ ​of​ ​the​ ​fire.​ ​When​ ​I
was​ ​turning​ ​the​ ​valve,​ ​it​ ​was​ ​difficult​ ​to​ ​adjust​ ​it​ ​to​ ​a​ ​proper​ ​extent;​ ​the​ ​fire​ ​was​ ​either​ ​too​ ​weak
or​ ​too​ ​strong.​ ​Due​ ​to​ ​this,​ ​the​ ​water​ ​of​ ​crystallisation​ ​might​ ​not​ ​have​ ​been​ ​driven​ ​off​ ​steadily.
Another​ ​limitation​ ​was​ ​that​ ​I​ ​was​ ​able​ ​to​ ​do​ ​only​ ​one​ ​trial,​ ​so​ ​I​ ​couldn’t​ ​really​ ​find​ ​out​ ​if​ ​the
mass​ ​of​ ​hydrated​ ​copper(II)​ ​sulfate​ ​has​ ​effect​ ​on​ ​the​ ​mass​ ​of​ ​water​ ​lost​ ​through​ ​decomposition.

So​ ​one​ ​area​ ​where​ ​I​ ​can​ ​improve​ ​my​ ​experiment​ ​would​ ​be​ ​the​ ​number​ ​of​ ​trials;​ ​If​ ​I​ ​were
to​ ​do​ ​this​ ​experiment​ ​again,​ ​I​ ​would​ ​do​ ​more​ ​than​ ​one​ ​trial​ ​so​ ​I​ ​can​ ​figure​ ​out​ ​the​ ​answer​ ​for​ ​the
research​ ​question​ ​experimentally​.​ ​Another​ ​point​ ​where​ ​I​ ​could​ ​improve​ ​on​ ​is​ ​about​ ​time.​ ​For​ ​this
experiment,​ ​I​ ​did​ ​not​ ​measure​ ​for​ ​how​ ​long​ ​I​ ​heated​ ​the​ ​crucible;​ ​instead​ ​of​ ​timing​ ​during​ ​the
heating​ ​process​ ​using​ ​a​ ​stopwatch,​ ​I​ ​just​ ​waited​ ​until​ ​the​ ​color​ ​of​ ​the​ ​copper(II)​ ​sulfate​ ​went
greyish​ ​white.​ ​Even​ ​though​ ​the​ ​procedure​ ​did​ ​not​ ​say​ ​anything​ ​about​ ​measuring​ ​time​ ​and​ ​it​ ​only
said​ ​“heat​ ​until​ ​the​ ​color​ ​of​ ​the​ ​crystal​ ​fades​ ​to​ ​greyish​ ​white”,​ ​I​ ​think​ ​it​ ​would​ ​have​ ​been​ ​useful
to​ ​record​ ​the​ ​time.​ ​Involving​ ​time​ ​could​ ​lead​ ​to​ ​a​ ​possible​ ​extension​ ​to​ ​this​ ​investigation.​ ​If​ ​I
measured​ ​time,​ ​I​ ​could​ ​even​ ​have​ ​calculated​ ​how​ ​long​ ​it​ ​takes​ ​to​ ​fully​ ​decompose​ ​a​ ​hydrated
copper(II)​ ​sulfate​ ​crystal​ ​depending​ ​on​ ​the​ ​mass.​ ​This​ ​relates​ ​back​ ​to​ ​having​ ​more​ ​than​ ​one​ ​trial;
I​ ​can​ ​do​ ​various​ ​trials,​ ​time​ ​each,​ ​and​ ​find​ ​the​ ​correlation​ ​between​ ​the​ ​time​ ​taken​ ​to​ ​become
anhydrous​ ​copper(II)​ ​sulfate​ ​and​ ​the​ ​mass​ ​of​ ​crystals.​ ​And​ ​then​ ​I​ ​could​ ​also​ ​have​ ​create​ ​a​ ​general
formula/equation​ ​that​ ​shows​ ​the​ ​correlation.
 Works​ ​Cited

“BBC​ ​-​ ​GCSE​ ​Bitesize:​ ​Reversible​ ​Reactions.”​ ​N.p.,​ ​n.d.​ ​Web.​ ​29​ ​Oct.​ ​2017.

“Hydrate​ ​|​ ​Chemical​ ​Compound.”​ ​Encyclopedia​ ​Britannica​.​ ​N.p.,​ ​n.d.​ ​Web.​ ​29​ ​Oct.​ ​2017.

“Law​ ​of​ ​Definite​ ​Proportions​ ​|​ ​Chemistry.”​ ​Encyclopedia​ ​Britannica​.​ ​N.p.,​ ​n.d.​ ​Web.​ ​29​ ​Oct.

2017.

Pubchem.​ ​“Copper(II)​ ​Sulfate​ ​Pentahydrate.”​ ​N.p.,​ ​n.d.​ ​Web.​ ​30​ ​Oct.​ ​2017.