Significant figures minimization, rounding errors

The values for K, listed here have been calculated from pK, values with more significant figures than shown so as to minimize rounding errors. Values for polyprotic acids—those capable of donating more than one proton—refer to the first deprotonation. 

Note To minimize rounding errors, keep all your numbers in your calculator until the end, then round to the appropriate number of significant figures. 

Note The answers to each step were rounded to the correct number of significant figures. However, the entire number has been kept in the calculator and used throughout the entire calculation to minimize rounding errors. 

Note In the following calculations, the answers that are in parentheses contain too many significant figures, but are the ones used in the progressive calculation in order to minimize rounding errors. 

We can use the ideal gas equation to solve for the concentrations of H2 and I2. We can then solve for the initial rate in terms of H2 and I2 and then convert to the initial rate of formation of HI. We cany an extra significant figure throughout this calculation to minimize rounding errors. 

Step 1 Calculate the initial concentration of NOCl. We carry an extra significant figure throughout this calculation to minimize rounding errors. 

The charges of the M and X ions are -i-3 and -2, respectively (are other values possible ). We first calculate the number of moles of M2X3 that dissolve in 1.0 L of water. We cany an additional significant figure throughout this calculation to minimize rounding errors. 

We can calculate Kp using the following equation. We carry additional significant figures in the calculation to minimize rounding errors when calculating Kp. 

Set up a table that contains the initial concentrations, the change in concentrations, and the equilibrium concentrations. The initial concentration of 12(g) is 0.054 mol/0.48 L = 0.1125 M. The amount of I2 that dissociates is (0.0252)(0.1125 A/) = 0.002835 M. We carry extra significant figures throughout this calculation to minimize rounding errors. 

Step 1 AG° was calculated in part (a). We must calculate Qp. We cany additional significant figures in this calcnlation to minimize rounding errors. 

Remember that we keep extra significant figures until the end of a multi-step problem to minimize rounding error. [W Section 1.5]... 

---