Chemical reaction between bleach and lemon juice
Description
In this experiment students add lemon juice to bleach (previously added phenolphthalein) observing
color changes.
Safety
See hazards in Table 1.
Greenness assessment
For the assessment Green Star (GS) was used, results in Fig. 1.
3
P12
P1
2
P5
1
0
P10
P6
P7
GSAI = 41.67
Figure 1. Greenness assessment (GS)
Construction of GS
In Table 1 are presented the hazard codes and the classification of hazards and in Table 2 the
components and punctuations to construct the GS.
Table 1. Hazards of materials usedα
Score: hazards to...
Reagents
Hazard codes
H
E
P
Reagents
Lemon juiceb,c
-
1
1
1
Bleachc,d
-
2
1
1
H225; H341; H350
3
1
3
Water
-
1
1
1
Sodium citrate
-
1
1
1
3
3
3
Phenolphtalein
Waste
H270; H315; H319; H331;
H335; H400
α
H – Health; E – Environment; P –Physical; - not present.
Chlorine
b
Renewable
Degradable to innocuous products
d
Without SDS, moderate hazard considered to health based on the label
c
Table 1. Scores (S) used to construct the Green Star
Green Chemistry Principle
S
Explanation
P1
Prevention
1
Chlorine, H331; H400
P5
Safer solvents and auxiliary substances
3
No solvents or auxiliary substances
P6
Increase energy efficiency
3
Room temperature and pressure
P7
Use renewable feedstocks
2
At least one raw materials/feedstocks (water excluded) is
renewable
P10
Design for degradation
1
At least one substance is not degradable to innocuous
products
P12
Safer chemistry for accident prevention
1
Chlorine, H270; H331
Pnenolphtalein, H225; H341; H350
References
Fiolhais, C.; Morais, C.; Paiva, J.; Costa S.; Gil, V. 8 CFQ - Sustentabilidade na Terra, Texto Editora,
Lisboa, 2007.