To measure Ca in breakfast cereal, 0.521 6 g of crushed Cheerios was ashed in a crucible at 600C in air for 2 h.32 The residue was dissolved in 6 M HCl, quantitatively transferred to a volumetric flask, and diluted to 100.0 mL. Then 5.00-mL aliquots were transferred to 50-mL volumetric flasks. Each was treated with standard (containing 20 micrograms/ml ), diluted to volume with H2O , and analyzed by flame atomic absorption. Construct a standard addition graph and use the method of least squares to find the x-intercept and its uncertainty. Find wt% Ca in Cheerios and its uncertainty. Ca2+ Standard Absorbance (mL)
0 0.151
1 0. 0.185
3.0 0.247
5.0 0.300
8.0 0.388
10.0 0.445
15 0.572
20 0.723