Question

3. (10 pts) A solution is prepared by dissolving 0.8434 (+/-0.0005) g of Pb(NO3)2 8 0.8434 (+/- 0.0005) g of Pb(NO3)2 (FM 331.111 +/- 0.009) in 250.0 (+/- 0.1) mL. Find the molarity and its uncertainty with an appropria number of significant figures.

Answer 1

Solution :- Calculation of Molarity CC) and uncertainity of Molarity. Molarity is calculated as - C=ņ i no no. of moles V = volume of solution in Liteve J Colemany [ na ] CS m n may Mola may M. V m: 0.824349, M = 331.111 , V= 250 ml C = 0.8434 x 1000 = 331-111 X250 843:4 8277.75 moll? = 0.0102887 molti It is assumed that the uncertainties of mass, Molar. mass and volume are not correlated. Hence, the uncertainity of the molarity can be calculated as - (wc )* = (4.com) * + (ance) + (cm3)? aco - Alucas), (ugoy lacusa uco a pouco*(41 CV]*C

LUCO) 7 3.51457x167 + 0.00738 X107 + 1.6X167 x 0.010288 5.12195 xio7 x 0.0102887 0.512195 X106 x 0.0102887 0.715678 X0.0102887 X10-3 0.00000736 mol L. 0.000007 molt ~ Hence, the Molarity of the solution is 0.0102887 molt and uncertainty in molarity is 0.000007 molt Pie C = 0.0102887 0.0.000007) moll'.