Tutorial Questions

Question

• Q1. What is analytical chemistry?
• Q2. Distinguish between qualitative analysis and quantitative
analysis. Give examples of each analysis.
• Q3. Outline the steps commonly employed in an analytical
procedure. Briefly describe each step.
• Q4. Distinguish between analyse, determine, sample matrix,
and analyte.
• Q5. Define accuracy and give an example.
• Q6. Define precision and give an example.
• Q7. What is percentage error and give an example.
• Q8. Differentiate between a random error and systematic
error

Answer 1

• Q1. Analytical chemistry is the branch of chemistry that deals with the identification and measurement of the chemical composition of substances.

• Q2. Qualitative analysis involves identifying the components of a sample without measuring their amounts, while quantitative analysis involves determining the amount of each component present in a sample. An example of qualitative analysis would be identifying the presence of a specific metal ion in a solution, while an example of quantitative analysis would be measuring the concentration of that metal ion in the solution.

• Q3. The steps commonly employed in an analytical procedure include sample collection, sample preparation, analysis, and data interpretation. Sample collection involves obtaining a representative sample, sample preparation involves manipulating the sample to make it suitable for analysis, analysis involves using analytical techniques to measure the sample, and data interpretation involves analyzing and drawing conclusions from the data obtained.

• Q4. Analyze refers to the process of determining the composition of a sample, determine refers to finding the quantity of a component in a sample, sample matrix refers to the material in which the analyte is present, and analyte refers to the substance being analyzed.

• Q5. Accuracy refers to how close a measured value is to the true value. For example, if a laboratory experiment determines the true value of a substance as 10 grams, and a measurement is made with a result of 9.8 grams, the measurement is considered accurate.

• Q6. Precision refers to the reproducibility of the results obtained from multiple measurements of the same sample. For example, if multiple measurements of the same sample all give results of 9.8 grams, the measurements are considered precise.

• Q7. Percentage error is a measure of the accuracy of a measurement and is calculated by dividing the absolute error by the true value and multiplying by 100%. For example, if the true value of a substance is 10 grams and a measurement results in 9.5 grams, the percentage error would be 5%.

• Q8. A random error is an error that occurs randomly and can be positive or negative, resulting in fluctuations in measurements. A systematic error is a consistent error that occurs in the same direction each time a measurement is made, resulting in consistently inaccurate results.