Chemical reaction between silver nitrate and potassium chromate
Description
In this experiment students add two aqueous solutions of silver nitrate and potassium chromate and
check the formation of a precipitate.
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 = 33.33
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
H315; H318; H410
3
3
1
H317; H340; H350i; H411
3
3
1
Silver chromate
H272 (category 2); H317; H350i;
H410
3
3
3
Potassium nitrate
H272 (category 3)
1
1
2
Reagents
Silver nitrate (aqueous solution)
Potassium chromate (aqueous solution)
Waste
α
H – Health; E – Environment; P –Physical; - not present.
Table 1. Scores (S) used to construct the Green Star
Green Chemistry Principle
S
Explanation
P1
Prevention
1
Silver chromate, H350i; H410
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
1
None of the raw materials/feedstocks (water excluded) are
renewable
P10
Design for degradation
1
P12
Safer chemistry for accident prevention
1
At least one substance is not degradable to innocuous
products
Silver nitrate, H318
Potassium chromate, H340; H350i
Silver chromate, H272 (category 2); H350i
References
Dias, F. M. L.; Rodrigues, M. M. R. D. Física e Química na Nossa Vida – As nossas atividades – 8ºano,
Porto Editora, Porto, 2010.