Molecular Biology Lab

8/17/2019 Molecular Biology Lab

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Kristin Moser

Pre-Lab No. 2

Solutions, Acids, & Bases

The pH Scale

Group 1

Section B1

Joanne Park !u"ust Tan Jin" #an

$ate% &'(1)(1)



!bstract

The ob*ecti+e o, this eperient is to un/erstan/ olarit0 o, solutions an/ be able to test their

pH +alue. Besi/es testin" aci/s an/ bases bu,,ers ill also be teste/ to /eterine their

e,,ecti+eness on such solutions. ertain coercial antaci/s use/ ,or e/icinal purposes ill be

teste/ to pro+e their e,,ecti+eness.

Materials

• Test tubes

• 3ine"ar

• Ski ilk

• !pple *uice

• Grape,ruit *uice

• Butterilk

• Black co,,ee

• Sprite

• Househol/ bleach

• Miture o, Sprite an/ bakin" so/a

• 1& M h0/rochloric aci/

• &.1 M h0/rochloric aci/

• $istille/ ater

• Tap ater

• Phosphate sul,ur

• Nal

• Brocresol purple in/icator

• pH papers

•

Para,il• Late "lo+es

• !ntaci/

• Pipettes

• Lab oat

• Pen

• Paper



Proce/ure

Measurin" the pH o, li4ui/s%

• Measure the ,olloin" li4ui/s usin" a ,resh pH paper ,or each li4ui/%

o 3ine"ar

o Ski ilk

o !pple *uice

o Grape,ruit *uice

o Butterilk

o Black co,,ee

o Sprite

o Househol/ bleacho Miture o, Sprite an/ bakin" so/a

o 1& M h0/rochloric aci/

o 1.& M h0/rochloric aci/

o $istille/ ater

o Tap ater

• 5se the ,olloin" e4uation to check the easureents o, the h0/rochloric aci/%

Test the abilit0 to o, bu,,ers to stabili6e pH%

• Label ,our test tubes ,or the ,olloin" substances% 7ater &.1 M Nal Ski ilk &.1 M

Phosphate sul,ur.

• !// )L o, each solution into the appropriate test tubes.

•Measure each solution8s pH +alue an/ recor/ it in a table.

• 9i+e /rops o, aci/ shoul/ no be a//e/ to &.1 M Hl. No "entl0 i the solution b0

co+erin" the top o, the test tube ith para,il an/ in+ertin" the tube.

• :etest the pH o, the ne solution.

• :epeat a//in" aci/ to the rest o, the substances an/ test its ne pH.



Test the e,,ecti+eness o, coercial antaci/s%

• $eterine one /ose o, the antaci/ an/ use a ortar an/ pestle to turn the antaci/ into a

po/er.

• $issol+e the antaci/ po/er into 1&&L o, /istille/ ater.

• Place 1&L o, the ater an/ antaci/ solution into a test tube.

• 9our /rops o, brocresol purple in/icator to the test tube.

• Mi the solution "entl0 b0 placin" para,il o+er the top o, the test tube an/ in+ertin" the

tube.

• &.1 M Hl shoul/ no be a//e/ one /rop at a tie to the tube an/ ie/ a,ter e+er0

/rop. $o this until the solution turns 0ello.

Theoretical Pre/ictions

!ll the substances liste/ belo ill ha+e their pH +alue teste/. These are 0 pre/ictions on hat

their pH +alue ill be hen teste/ in the lab. Soe o, these +alues ; recei+e/ ,ro research or

the lab anual.

3ine"ar < = >3o/opich 2&&?@

Ski ilk - A

!pple *uice <

Grape,ruit *uice - 2

Butterilk - A



Black co,,ee- ) >3o/opich 2&&?@.

Sprite - =

Househol/ bleach-12.)

Miture o, Sprite an/ bakin" so/a < ?

1& M h0/rochloric aci/ - 1&

1.& M h0/rochloric aci/ - '

$istille/ ater -? >pH 3alue 2&&'@

Tap ater < A.?

Since broocresol purple is use/ to /etect aci/s ; think that the solution a/e ith the antaci/

ill pro+e ine,,ecti+e >National enter ,or Biotechnolo"0 ;n,[email protected] broocresol purple

ill ake the solution turn 0ello there,ore /etectin" the presence o, an aci/. This ill sho

ho coercial antaci/s /o not ork as ell as e a0 think.

Lab Cuestions

1

2)" o, sucrose



2)" o, calciu chlori/e

)" o, calciu chlori/e

2

1.A2) " o, Nal

1.A2)" o, Nal

?A" o, sucrose



.&?A" o, sucrose

12.=2" o, calciu chlori/e

." o, calciu chlori/e

AD." o, su"ar

.&?= oles o, su"ar. &.&&&1A M solution.



.22 oles o, calciu chlori/e. .&&& M solution.

)&&L o, sucrose solution

=

12) L o, sul,uric aci/.



2&L stock solution E D& L ater.

=&&L o, ater

7ork ite/

3o/opich $.S. Introduction to Cellular and Molecular Biology Lab. Ne-#ork% McGra-Hill

2&&? p. 2&.

PH 3alue o, oon Substances. >2&&'@. :etrie+e/ Septeber 1) 2&1).

National enter ,or Biotechnolo"0 ;n,oration. Pubhe opoun/ $atabaseF ;$D2?=

>:etrie+e/ Sept. 1) 2&1)@.

Kristin Moser

Post-Lab No. 2

Solutions, Acids, & Bases

The pH ScaleGroup 1

Section B1

Joanne Park ubair Hale



$ate% &'(22(1)

;n-lass Proce/ure

9or the ,irst part o, the eperient /i,,erent solutions ere teste/ to /eterine their pH

+alue. These solutions ere ,oun/ in correspon/in"l0 labelle/ beakers. eraic palettes ith

three ros an/ ,our coluns ere han/e/ out. Stras ere use/ throu"h capillar0 action to place

three saples o, each solution in one colun. Since each "roup as "i+en to ceraic platters

enou"h ,or ei"ht solutions this as repeate/ three ties. ;n the ,irst ro a hal, o, a blue litus

paper as place/. ;n the secon/ ro a hal, o, a re/ litus paper as place/. ;n the thir/ ro a



hal, o, a pH strip as place/. !n0 chan"e in color ,or either litus paper as recor/e/ in a table

>,oun/ in results@. Net the pH strips color as teste/ a"ainst the ke0 on the pH strip container.

The secon/ part o, the eperient re4uire/ /istille/ ater &.1M Nal ski ilk an/

&.1M phosphate bu,,er o, ) L +olue each to be put in separate test tubes. The initial pH o, the

solutions as taken usin" a pH strip an/ recor/e/. Ten /rops o, aci/ as a//e/ to each solution

an/ ie/. The pH a,ter as taken usin" a pH strip an/ recor/e/.

;n the thir/ an/ ,inal part o, the eperient the e,,ecti+eness o, certain coercial

antaci/s ere teste/. 9i+e L o, rea/0-a/e solutions o, !lka-Selt6er hite Tus an/ bakin"

so/a ere a//e/ to separate test tubes. 9our /rops o, brocresol purple in/icator as a//e/ to

each test tube an/ ie/. The initial colors o, the solutions ere note/. Then aci/ as a//e/ one

/rop at a tie an/ ie/ a,ter e+er0 /rop until the solution turne/ 0ello or 1&& /rops as

reache/. The nuber o, /rops as recor/e/.

:esults

Proce/ure 1%

T% Theoretical B% Be,ore !% !,ter N!% Not a+ailable

Iperiental

:ea"ent

Blue Litus Paper

>chan"es i, aci/ic@

:e/ Litus Paper

>chan"es i, basic@

pH strip

Pre/ictions(:esults T B ! T B ! T B !

3ine"ar N! Blue :e/ N! :e/ :e/ = & A-?

Ski Milk N! Blue Blue N! :e/ :e/ A & ?-D

!pple Juice N! Blue :e/ N! :e/ :e/ & A-?

Grape,ruit Juice N! Blue :e/ N! :e/ :e/ 2 & A-?

ranberr0- N! Blue :e/ N! :e/ :e/ N! & )-A



poe"ranate Juice

Butterilk N! Blue :e/ N! :e/ :e/ A & A-?

Black o,,ee N! Blue Blue N! :e/ :e/ ) & A-?

Black Tea N! Blue Blue N! :e/ :e/ N! & A-?

Green Tea N! Blue Blue N! :e/ :e/ N! & A-?

Sprite N! Blue :e/ N! :e/ :e/ = & )-AHousehol/ Bleach N! Blue N! N! :e/ N! 12.) & N!

Miture o, bakin"

so/a an/ Sprite

N! Blue Blue N! :e/ Blue ? & '-1&

Bakin" So/a N! Blue Blue N! :e/ Blue N! & '-1&

1& M Hl N! Blue :e/ N! :e/ :e/ 1& & -)

1.& M Hl N! Blue :e/ N! :e/ :e/ ' & -)

.&1 M Hl N! Blue :e/ N! :e/ Blue N! & )-A

$istille/ 7ater N! Blue Blue N! :e/ :e/ ? & A-?

Tap 7ater N! Blue Blue N! :e/ :e/ A.? & A-?

Proce/ure 2%

;nitial pH pH a,ter aci/

$istille/ 7ater ? =-

&.1M Nal A-? =-

Ski Milk A-? )-A

&.1M Phosphate Bu,,er A-? A-?

Proce/ure =%

Solution Nuber o, $rops o, !ci/

!lka-Selt6er )

7hite Tus '

Bakin" So/a 1&&

Lab Photos%

Proce/ure 1

Figure 1: Procedure 1: Cronberry-pomegranate juice, buttermilk, cofee, and black tea

Figure 2: Procedure 1: Green tea, Sprite, 01!bleac", Sprite and baking #oda



Proce/ure 2%

Figure $: Procedure 1: %ap &ater and di#tilled &ater Figure ': Procedure 1: (aking #oda, 10m) *Cl,01 m) *Cl, and 001 m) *Cl

Figure +: Procedure 1: inegar, #kim milk, apple juice,and graperuit juice



Proce/ure =%

Lab Notes%

pH after

acid: 0.1

phospha

pH after

acid: WaterInitial pH:

0.1M

phosphate

Initial pH:

Skim milkInitial pH:

0.1M NaClInitial pH:

Water pH after

acid: Skim

milk

pH after

acid: 0.1M

NaCl

Figure .: Procedure ': (aking #odaater 100 drop# o acid

Figure /: Procedure ': lka-#elteater + drop# o acid

Figure : Procedure ': %um# ater 3drop# o acid

ums solution

initial color

!akin" soda

solution initiacolor

lka$selt%er

olution initial

olor



onclusion

9or proce/ure 1 o, the eperient un,ortunatel0 not an0 pre/ictions ere a/e to

copare the results to. But the pre/ictions that ere a/e /i/ not pro+e correct. !ccor/in" to

3o/opich the pH o, +ine"ar shoul/ ha+e been aroun/ = >2&&?@. Base/ on proce/ure 1 o, the

eperient +ine"ar /i/ turn blue litus paper re/ pro+in" it as an aci/F hoe+er the pH

shoe/ a color close to oran"e in/icatin" a pH in the ran"e o, A-?. !nother stran"e result that

occurre/ as that &.&1M o, Hl turne/ blue litus paper re/ an/ re/ litus paper blue. !s an

aci/ &.&1M o, Hl as suppose/ to turn blue litus paper re/ but not suppose/ to turn re/

litus paper blue. Base/ on The pH Scale it akes sense that &.&1M o, Hl is sli"htl0 ore

basic than .1M or 1.&M o, Hl >Tun" 2&1=@. ;t has a saller concentration o, HE as the

olarit0 /ecreases. !lso the househol/ bleach as unable to "et accurate results because o,

bleach8s capabilit0 to reo+e color ,ro solutions. 7hen blue litus paper re/ litus paper

an/ the pH strip ere place/ in the househol/ bleach the color as reo+e/ an/ the papers

appeare/ hite.

;n proce/ure 2 the reason there as such a stron" chan"e in pH ith both the /istille/

ater an/ the Nal solution is because both contain H2 olecules hich ill /issociate an/

increase its HE concentration ith the a//e/ HE concentration ,ro the Hl. Since the ain *ob



o, a bu,,er is to ,in/ an e4uilibriu beteen the HE an/ H- concentration it akes sense that

the &.1M phosphate bu,,er as una,,ecte/ b0 the a//ition o, Hl. The pH +alue reaine/

relati+el0 the sae there,ore the bu,,er /i/ its *ob ell.

;n proce/ure = the !lka-selt6er pro+e/ least e,,ecti+e hen onl0 a,ter ) /rops /i/ the

solution turn 0ello. The hite Tus as the secon/ least e,,ecti+e ith onl0 ' /rops until it

turn 0ello. The bakin" so/a as the ost e,,ecti+e antaci/. !,ter 1&& /rops >hich as the

aiu alloe/@ the bakin" so/a still /i/ not turn 0ello.

Sources o, Irror

7hile testin" the pH +alue o, bleach in proce/ure 1 the results ere inconclusi+e because the

bleach bleache/ the paper hite. This coul/ not ha+e been a+oi/e/ because the eperient

re4uire/ the use o, a pH strip an/ litus paper not a pH eter.

7hen Hl as a//e/ to /istille/ ater &.1M Nal phosphate bu,,er an/ ski ilk 1& /rops

ere suppose/ to be a//e/. ! /rop is not a speci,ic easureent an/ coul/ +ar0 per person so

there as probabl0 a sall +ariation in the aount o, aci/ a//e/ to each test tube. ;, this

eperient as ore precise this a0 ske the results but it shoul/n8t ha+e ha/ an0 e,,ect on

the pH +alues recor/e/ in the en/.

Lab Cuestions

A



Bakin" so/a neutrali6es the ost aci/ an/ !lka-selt6er neutrali6es the least.

This 4uestion can8t be ansere/ because the nuber o, tablets use/ is unclear. Solutions use/

ere pre-a/e.

Tus < calciu carbonate

!lka-selt6er- !nh0/rous citric aci/ aspirin so/iu bicarbonate

Bakin" so/a- so/iu bicarbonate

;t appears that !lka-selt6er an/ bakin" so/a ill ork better as antaci/s because the0 contain

H- in their olecular structure hich is knon as the basic olecule. ;t also sees like Tus

oul/n8t ork e,,ecti+el0 unless it coes in contact ith ater because than the o0"ens ,ro

the calciu carbonate can bon/ ith the h0/ro"ens ,ro ater to ,or H-.

?

!lka-selt6er per,ore/ orse than epecte/. ;t as the eakest o, the antaci/s. The Tus

solution hoe+er per,ore/ as epecte/ because it as /issol+e/ in ater hich a/e it ore

e,,ecti+e. The bakin" so/a as the ost e,,ecti+e.

7hen /issol+e/ in ater these pro/ucts break apart ater to create a lar"e concentration o, H-

olecules hich balances out the lar"e aount o, HE olecules in the aci/.



7ork ite/

asi/0 :. 9re0 :. >1'''@. Bloo/ Seat an/ Bu,,ers% PH :e"ulation $urin" Iercise. :etrie+e/

Septeber 21 2&1).

Tun" I. Tsao S. Sin"h $. Gorle0 P. >2&1= ctober 2@. The pH Scale. :etrie+e/

Septeber 21 2&1).

3o/opich $.S. Introduction to Cellular and Molecular Biology Lab. Ne-#ork% McGra-Hill

2&&? p. 2&.

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Molecular Biology Lab