Evaluation of purity with its uncertainty value in high purity lead stick by conventional and electro-gravimetric methods

Table 6 Uncertainty in atomic mass of lead Metal

Element	Atomic mass of lead (g)	Uncertainty in weight (g)	Distribution	Standard uncertainty	Combined standard uncertainty
Pb	207.19	0.1	Rectangular	0.1/√3=0.05773	0.0578 (PbSO₄)
S	32.065	0.005	Rectangular	0.005/√3=0.00289^#
O^#	15.9994	0.0003	Rectangular	0.0003/√3=0.00017^# =0.00017*4=0.00068
O^#	15.9994	0.0003	Rectangular	0.0003/√3=0.00017^# =0.00017*2=0.00034	0.0577 (PbO)

In gravimetry lead obtained in the form of PbSO₄/ PbO_2;
O^# four atoms of oxygen have been considered in combined uncertainty for PbSO₄ and two atoms have been considered for PbO.

ISSN: 2661-801X