Determination of Moisture Content

ACTIVITY 1

Application of Statistical Concepts in the Determination of Weight Variation in Samples

Objective: To apply statistical concepts in analytical chemistry

Procedure:

1. Prepare 10 samples. Handle them with forceps to ensure that there will be no fingerprints on the samples. Use a watch glass as a sample container.

2. Take the weights of the 10 samples.

3. Record all the weights of the samples.

Data:

Group 1 | Group 2 | Group 3 | Group 4 |

Sample | Mass (g) | Sample | Mass (g) | Sample | Mass (g) | Sample | Mass (g) |

1 | 2.4532 | 1 | 2.5673 | 1 | 3.2871 | 1 | 2.6452 |

2 | 2.5387 | 2 | 3.4512 | 2 | 3.0021 | 2 | 2.7418 |

3 | 3.0062 | 3 | 2.4221 | 3 | 2.9752 | 3 | 2.9891 |

4 | 2.3537 | 4 | 2.3316 | 4 | 2.8641 | 4 | 2.2211 |

5 | 2.4531 | 5 | 2.5312 | 5 | 2.1198 | 5 | 2.1209 |

6 | 2.5376 | 6 | 2.5555 | 6 | 2.3510 | 6 | 2.3518 |

7 | 2.6429 | 7 | 2.5016 | 7 | 2.5301 | 7 | 2.7790 |

8 | 2.2910 | 8 | 2.4124 | 8 | 2.0021 | 8 | 2.8610 |

9 | 2.5111 | 9 | 2.3213 | 9 | 2.4156 | 9 | 2.6519 |

10 | 2.3728 | 10 | 2.1278 | 10 | 2.7498 | 10 | 2.5616 |

Calculations:

1. Divide the samples into the following data sets:

Data Set 1: Samples 1 to 6

Data Set 2: Samples 1 to 10

2. Perform the Q-test (at 95% confidence level) for the highest and lowest values of both data sets.

3. Calculate the following parameters for both data sets:

a. Mean

b. Standard deviation

c. Relative standard deviation (in ppt)

d. Range

e. Relative range (in ppt)

f. Confidence limits (95% confidence level)

g. Pooled standard deviation*

Discussion:

Discuss:

1. The significance of standard deviation

2. The significance of confidence limits

3. The significance of Q-test

4. How the statistical parameters calculated from data set 1 compare to those obtained from data set 2

5. The significance of pooled standard deviation*

6. How the mean of your group correlate to those obtained by...