Propagation of error: Consider the dissociation of acetic acid in aqueous solution: CH_3COOH + H_2O doubleheadarrow CH_3COO^- + H_3O^+ The expression of the Ka is: K_a = [CH_3COOH^-][H_3O^+]/[CH_3COOH] Calculate the error on the value of Ka using the following concentrations and corresponding errors: [CH_3COO^-] = 1.3420 times 10^-3 plusminus 0.0005 times 10^-3 [H_3O^+] = 1.3420 times 10^-3 plusminus 0.0001 times 10^-3 [CH_3COOH] = 0.10000 plusminus 0.0002 times 10^-3 Methods and significance: Small amounts of lead in adults are not thought to be harmful. However, even low levels of lead can be dangerous to infants and children. It can cause lead poisoning that leads to problems in mental development An original method (M1) for determination of lead (Pb) in blood provides a standard deviation of 0.25 mu g/dL with 11 trials (n=l1). A second method (M2) shows a standard deviation of 0.15 mu g/dL also with 11 trials. Is method M2 significantly more precise than the original method (M1) at the 95% level? (i.e. are the standard deviations significantly different at the 95% level?) Are the standard deviations significantly different if the method M2 used 21 trials (i.e. N=21); Are results of "a" and "b", when combined, logical? Explain. The means of blood lead levels found in a child suspected to be exposed to lead using the two methods are: 39.75 mu g/dL using Ml (N=l1) and 37.25 mu g/dL using M2 (N=l1) Are the two means significantly different at the 95% confidence level? Would the conclusion be the same if method M2 used 21 trials? Explain.