Question

I need help finding how to do the calculations for these tables. If you could show me how to do the 1st determination/ trial 1 for each of them, I can figure out how to do the second and third determinations/trials. If you could also show me how to do the standard deviations, that'd be much appreciated. Thank you!

TABLE 8.3 volume at 1st Determination | 26.30 mL 13.15 mL 2nd Determination 3rd Determination 26.40 ml 26.40 mL 13.20 mL 13.20 ml volume at half equivalence point K, (acid equilibrium constant) average standard deviation C. CONCENTRATION OF THE UNKNOWN ACID TABLE 8.4 Trial 1 Trial 2 Trial 3 volume of unknown acid 25.0 mL 25.0mL 25.0mL average molarity of NaOH mL of NaOH at equivalence point molarity of unknown acid average molarity standard deviation

Answer 1

At half equivalence point [salt] = [acid ] .. - pt=pkat logi.. pit=pka But hert tone is given. So it is not possible to determine the pra value Once you find the prea value you can use the following equation to find ka': ; pka — — w, yo Ka orka=10-pka] But from te geven information here it ñ not possible to find Kahere. Standard deviation calculation : Suppose we have a set of data - 10, 12, 13, 1, g. to calmelate standard devodevision deviation of those- i) we need to take their average (10+12+ Bt+8 = 54 = 1008 2. Then for each number subtract the average value and square the result: (10-10:8) = 0.64 (12-10-8) = 1:44 (13-2008) V=4.82 (11-1018) V=0.04001 18-10.8) ¥ 7.84 oj Vz0.04.. I 3. Add up all the values and then device by total numbers 1 : Sum=(0.647144+4.84 +0.04 +7.84) = 14.80 I Now mean of the squared differences = 14.80 = 2.96. 4. Take the to square root of that value.

. Standard deviation = 12.96 = 117205 Once you have the ka values you can determine- by following to way shoron here C. concentration of unknown (in molarity) has to determine by using vis, z82.52 relation. where v = volume of Unknown acid (25.0ml here) Si= concentration of unknown acid whe needs to be determined. V2= Volume of the base solution S2= concentration of base solution. In aced base titration when one quantity is required to find out, the other quantity should be Known. Therefore to find out concentration of aced here the volume and concentration of base solution must be known. Otherwise it is difficult to find out the value of concentration of acid . Once you known the concentration of acid the base, the volume of the the base (Naot here) will be determined from titration Putting this values in Visi= V232 relation you can find out concentration of unknown acid (S.). from there you can find out average molarity and standard deviation . of the these values It is not possible to determine the quantities asked here . M .