BTEC Level 3 Applied Science Assignment 2A: Titration & Colorimetry

Assignment 2A: Titration




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DATE: ________________

,Determining the concentration of Sodium Hydroxide by Titration
Risk Assessment
Risk Nature Precaution
Na 2 CO 3 solution Eye irritant Safety glasses
≥ 0.8 mol/dm
−3 (CLEAPPS, 2017) (CLEAPPS, 2017)
Hazcard 95a
HCl<2.7 mol /dm−3 Skin and eye irritant  Safety glasses
(CLEAPPS, 2017)  Lab coat
Hazcard 47A  Wash skin (if coming
into contact)
(CLEAPPS, 2017)
Methyl Orange Indicator  Flammable (including  No naked flames
vapours)  Safety glasses
Hazcard 32  Eye irritant  Small quantities
 Toxic if inhaled  Ventilation
 Skin burns  Wash skin (if coming
(CLEAPPS, 2017) into contact
(CLEAPPS, 2017)
Sodium hydroxide  Eye damage  Eye protection
−3
≥ 0.125 mol/dm  Harmful if infected in (CLEAPPS, 2017)
open skin
(CLEAPPS, 2017)


Results – data and calculations
Preparing a sodium carbonate (primary) standard
Mass of sodium carbonate used was 1.43g
M r of Na 2 CO 3
=( 22.990 ×2 ) +12.011+ ( 15.999 ×3 )
= 105.988

Moles of sodium carbonate used.
mass
moles=
Mr

1.43
¿
105.988
¿ 0.013492 mol

Calculating concentration of sodium carbonate used.

3 ÷1000
3
250.00 cm →
0.25000 dm

, moles
concentration=
volume
0.013492
¿
0.25
¿ 0.053968 mol /dm−3
¿ 0.054 mol /dm−3
Titration 1: hydrochloric acid and sodium carbonate (primary standard)

Titration 1 results table:
HCl Titre (cm 3) 1 2 3 4
Initial Reading 13.95 20.00 15.40 11.50
Final Reading 39.80 45.90 41.60 37.90
Volume of HCl 25.85 25.90 26.20 26.40
used (cm 3)
Volume of HCl 0.02585 0.0259 0.0262 0.0264
used (dm 3)


Balanced equation for reaction between HCl and Na 2 CO 3:

Na 2 CO 3 +2 HCl → 2 NaCl+ H 2 O+ CO2
Reaction ratio: 1 : 2

Calculating the concentration of HCl :

Na 2 CO 3 concentration is 0.054mol /dm−3
3 ÷1000
Volume of solution made is 25.00 cm →
0.02500 dm 3
3 ÷1000
HCl volume is 26.00 cm →
0.26000 dm
3




number of moles of Na2 CO 3=concentration of Na2 CO3 × volume of Na 2 CO 3
¿ 0.054 × 0.02
¿ 1.35 ×10−3 mol

number of moles of HCl=number of moles of Na 2 CO 3 × reactionratio
−3
¿ 1.35 ×10 ×2
−3
¿ 2.7 ×10 mol

number of moles of HCl
concentration of HCl=
volume of HCl used
−3
2.7 ×10
¿
0.026