Sampling And Evaluation Of Experimental Data, Exercises of Analytical Chemistry

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iii) Student 2. The (^) data In the set (^) are close to true (^) value each other I (^) from (^) increasing (

1. Data (^) (rearrange) = 490.00, 500.10,^ 510.50,^ 750. questionable detal^ neighbour 21 +288 = 8utlier - closest (^) neighbor (a) jauh (^) Range (w) x=490.98, (^) 50010, 510.50, 700.20 (^) Outlier:750. 9.2 10.4^ 239.^ ①(a) :(750.28-510.55) (750,20-49890) (^) range = 0. ↑Data ①table at^ 95% =0.829^ N^ =^4 Stable & (^) cal, the (^) value 750.20 (^) must (^) be rejected i) Accuracy is (^) how close (^) a (^) measured value is to the actual (^) (true) value (^) which is (^) believed to (^) be (^) correct ii) MEAN Student X:(515.50)^ +^ (478.58)

• (530.10) + (420.65) 4 :482. StudentX:(508.18)^ +^ (550.20)^ +^ (490-90)^ +^ (518.50) 4 :562. Student I:(600.48)^ +^ (610.50)^ +^ (590.80)^ +^ (600.0) 4 :600. The true^ value is (^) 500mg, (^) therefore student X (^) has the most accurate (^) result.

T-test (^) for (^) comparing Experimental Mean (^) with (^) the value i) Mean^ =^ 3.56^ +^ 2.^

• 2.73 + 1.85 + 2. 2 b = 2. ii) -1 - x t = spool) /Ni^ +N.^ ( N, xNc = 2.93- 3.25 t (^) table at 95% (L(DOF = 9-2) = 2. 0.095). (^) a) I test^ >^ t^ table 5.82 >^ 2. 28 =0.32 There^ is^ a^ significant difference^ between 10.095 x (^) 0.67002) the two (^) data, so^ the second data^ may notcome^ from^ the^ same (^) green tea^ extract. = 8.

· (^) If fest 12,^ tcre=reject = (^) 5.02 · Inest < (^) terce:accept

Iii (^) ) No (^) the (^) patient may not^ have jaundice since bilirubin (^) reading is (^) within normal range i (^) ) × suspect = ◦^ ' 92 Ii^ ) Mean =^ 2-^16 3 = ◦^ '^72 Q test =^ ✗ suspect

• (^) ✗ neighbor ✗ (^) mga -^ ✗^ min^ S =^ 0.1868 =^ 0- = (^) 0.92-0- (^991) ,^ , 2=2- 0-92 -^ 0- 99-91.^ ,^ 2=3- = (^0) - 0- = (^) 0- (^991). Confidence^ limit^ (^ CL^ )^ =^ 0.72+1-2.50×0.19^ /^ CIJ^ ) at 951 ,^ i^ Q (^) table a (^) 0-97 = 0-72 I^ 0- Q test <^ Q^ table^ confidence Interval^ ICI^ ) at^991. =^ 0-442-1- Value (^) 0.92 Should be accepted 99-9 (^) /◦ CL = 0.72+1-3.29×0.19 11533 = (^) 0.72 1- (^) 1- 0- 61 at^ 99.91. i (^) 0-359-1-

Two students, A and B were asked to determine the molar concentration of an iodine solution. The results obtained are as summarized in the following table. The actual concentration of the solution is 0. 240 M. Student Mean (M) Standard deviation (M) A 0.235 0. B 0.251 0. By comparing the data, determine and give a reason which student’s results is: i) more accurate. i) more precise. i. (^) Student A Is^ more^ accurate^ because^ the mean is^ closer^ to the true^ value^. i (^) student B is more (^) precise because^ the^ standard deviation is lower

Perform Q test to the following data set at 90 % confidence level and then determine the mean and standard deviation.

43. 2 42. 9 43. 6 45. 3 43. 4 Mean =^ (^ 43-2^ +^ 42-9^ +^ 43.^

• (^) 43-4 ) ① exp : (^) 145-3-43. 4 145.3-42-9 )^ : 43. =

s = ~ (43.2-43.3)^ '

• (^) (42-9-43-3) ≥
• (^) (43.6-43-3) ≥
• (^) (43.4-43.3) ' ! (^) table = 0.642 (4-1) = (^) 0- ① exp

① (^) table , outlier 145.3^ ) is (^) rejected

I known 7 ⑧ therefore^ choose^ & (^) in table If unknown Mean, (^) X = (54.0 + 53.

• 54.3) t =n-^1 Data = (^) 5+ . 90%confidence^ limitof the mean = (^) x (^) = 20 refer I (^) to 0 mean -^ - G = 54.25I(1.69x0.83) Iy, Data = (^) 57.25 1088 confidenceinternal (^0) 54.25 + (^) 0.60 = · (^) 54.27 - 0.60 = i. ?to?

Interference = (^) chemical species other^ than^ the^ analyte that^ causes^ a^ systematic error (^) in an analysis (^) by enhancing the (^) analytical signal of the analyte

• Masking
• (^) Distillation
• (^) Extraction
• Precipitation & filtration
• (^) Ion exchange

chromatography

• (^) Immobilize (^) Interference ie (^) interference becomes non reactive complex
• (^) Differences In (^) Volatility of (^) cpds
• (^) Differences in (^) solubility in 2 Immiscible (^) liquids
• (^) Differences in^ solubility of (^) cpds formed
• (^) Differences in^ stability of^ reactants^ with^ ion^ exchange resin
• Differences in (^) rate (^) of movement (^) of solute through (^) stationary phase Random (^) errors result (^) from uncontrollable variables in^ an (^) experiment systematic error are^ those which can be^ ascribed to^ a (^) particular cause and can^ usually be determined (^).