Analytical Chemistry Quiz & Flashcards: Lecture Notes

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Questions and Answers

What is the first step in the analytical process?

Define the problem (correct)

Prepare the sample for analysis

Select a method

Obtain a representative sample

What is the term for the process of collecting a small mass of material?

Analysis

Sampling (correct)

Measurement

Preparation

What is the difference between accuracy and precision?

Accuracy is how close to each other, precision is how close to the true value

Accuracy is how close to the true value, precision is how close to each other (correct)

Accuracy is a measure of systematic error, precision is a measure of random error

Accuracy is a measure of random error, precision is a measure of systematic error

What is the unit of the numerator in molarity?

moles of solute Signup and view all the answers

What type of error occurs when something is intrinsically wrong in the measurement?

Systematic error Signup and view all the answers

What is the formula for relative error?

(Absolute Error / True Value) x 100 Signup and view all the answers

What is the unit of the denominator in molality?

kilograms of solvent Signup and view all the answers

What is the percentage of sodium hydroxide in a solution if 25g of sodium hydroxide is dissolved in 100g of solution?

25% by mass Signup and view all the answers

What is the strategy for converting between concentration units?

g -> mol -> atoms Signup and view all the answers

What is the volume of hydrochloric acid in a solution if it is 75% by volume?

75 mL of HCl per 100 mL of solution Signup and view all the answers

What is the concentration of a 35% w/v HCl solution?

35 g of HCl in 100 mL of water Signup and view all the answers

Which of the following concentration units is temperature-independent?

Molality Signup and view all the answers

What is the minimum amount of energy required for a chemical reaction to occur?

Activation energy Signup and view all the answers

What is the term for the process where a solution contains more of the dissolved salt than it can hold?

Supersaturation Signup and view all the answers

What is the principle that states that a chemical reaction will shift in a direction to counteract any changes made to the system?

Le Chatelier's Principle Signup and view all the answers

What is the term for the highest potential energy point in a chemical reaction?

Transition State Signup and view all the answers

What is the process called when a precipitate is contaminated by other substances during its formation?

Coprecipitation Signup and view all the answers

What is the type of reaction that occurs only with the substance of interest?

Specific Reaction Signup and view all the answers

Study Notes

Analytical Process and Measurement Concepts

The first step in the analytical process is defining the problem or question to be resolved, setting the framework for investigation.
The process of collecting a small mass of material is referred to as sampling, crucial for representative analysis.
Accuracy refers to how close a measured value is to the true value, whereas precision reflects the reproducibility of measurements, regardless of their closeness to the true value.

Concentration Units and Solutions

The unit of the numerator in molarity is moles, signifying the amount of solute in a given volume of solution.
The unit of the denominator in molality is kilograms of solvent, representing the mass of the solvent in which the solute is dissolved.
To calculate the percentage of sodium hydroxide in a solution where 25g sodium hydroxide is dissolved in 100g of solution, use the formula: (mass of solute/mass of solution) x 100, resulting in 25%.

Conversion and Concentration Calculations

A strategy for converting between concentration units often involves using conversion factors that relate moles, volume, and mass.
For a hydrochloric acid solution that is 75% by volume, the volume of hydrochloric acid can be determined based on the total volume of the solution.
The concentration of a 35% w/v (weight/volume) HCl solution would be calculated as grams of HCl per 100 mL of solution, yielding concentration data for practical applications.

Chemical Reaction Principles

A temperature-independent concentration unit is molality, which is defined by the amount of solute in relation to the mass of the solvent.
The minimum amount of energy required for a chemical reaction to occur is known as the activation energy, a key concept in thermodynamics.
A solution that contains more dissolved salt than it can hold is termed supersaturated, indicative of dynamic balance in solutions.
Le Chatelier's principle states that a chemical reaction will adjust in response to changes in concentration, temperature, or pressure to restore equilibrium.

Energy and Reaction Mechanisms

The term for the highest potential energy point in a chemical reaction is the transition state, representing a critical moment in the transformation of reactants to products.
The process where a precipitate becomes contaminated by other substances during its formation is known as coprecipitation, affecting purity and outcome.
A reaction that occurs only with the substance of interest is known as a selective reaction, emphasizing specificity in chemical processes.

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Description

Test your knowledge of analytical chemistry with this quiz covering the introduction to analytical chemistry, methods of analysis, experimental error, and steps in the analytical process. Learn about chemical characterization of matter, qualitative and quantitative analysis, and more.