Gravimetric Analysis Quiz

What is the principle of gravimetric analysis?

• Measures the quantity of an analyte using temperature

• Measures the quantity of an analyte using density

• Measures the quantity of an analyte using weight

• Measures the quantity of an analyte using volume

Answer explanation

Gravimetric analysis is a technique in analytical chemistry that determines the quantity of an analyte (the substance being measured) by measuring its mass. The process typically involves converting the analyte into a stable, pure compound of known composition that can be easily weighed. The principle behind this method is that the mass of the resulting compound is directly related to the amount of the original analyte present in the sample. By carefully measuring this mass, the concentration of the analyte can be accurately calculated.

What are the applications of gravimetric analysis?

• Calculating the density of a liquid

• Measuring the volume of a gas

• Determining the color of a compound

• Monitoring lead levels in water

Answer explanation

Gravimetric analysis is used to monitor lead levels in water by measuring the mass of a precipitate formed when lead reacts with a specific reagent. The process involves filtering, drying, and weighing the precipitate to determine the concentration of lead, making it a precise and reliable method for detecting and quantifying lead contamination in water.

What is the distinction between volumetric and gravimetric analysis?

• Volumetric measures weight, gravimetric measures volume

• Volumetric measures density, gravimetric measures temperature

• Volumetric measures volume, gravimetric measures weight

• Volumetric measures temperature, gravimetric measures density

Answer explanation

The distinction between volumetric and gravimetric analysis is as follows:

• Volumetric Analysis involves measuring the volume of a solution to determine the concentration of a substance.

• Gravimetric Analysis involves measuring the weight of a substance to determine its quantity.

In summary, volumetric analysis is based on volume measurements, while gravimetric analysis is based on weight measurements.

What are the two essential kinds of gravimetric techniques?

• Volatilization and Precipitation

• Volatilization and Thermogravimetric

• Thermogravimetric and Electrogravimetry

• Precipitation and Electrogravimetry

Answer explanation

The two essential types of gravimetric techniques are volatilization and precipitation.

• Volatilization involves converting a substance into a gas, which is then collected and weighed to determine the amount of the analyte in the original sample.

• Precipitation involves forming an insoluble compound (precipitate) from the analyte, which is then filtered, dried, and weighed to determine its quantity.

These techniques are fundamental in gravimetric analysis for quantifying the amount of a substance based on its mass.

What are the steps commonly followed in gravimetric analysis?

• Adding a precipitating agent to the solution

• Weighing the isolated constituent

• Heating the sample in an oven

• Mixing two unknown compounds

Answer explanation

In gravimetric analysis, the primary steps typically followed are:

1. Preparation of Sample: The sample is prepared by dissolving it in a suitable solvent, usually through heating or other chemical reactions.

2. Precipitation: The target constituent in the sample is precipitated by adding a reagent that reacts with it to form an insoluble compound.

3. Filtration: The precipitate is separated from the solution by filtration.

4. Washing: The precipitate is washed to remove impurities or any adhering ions.

5. Drying or Ignition: The washed precipitate is dried (or ignited if necessary) to remove moisture or convert it into a more stable form.

6. Weighing: The dried precipitate is accurately weighed. This step involves determining the mass of the isolated constituent, which is then used to calculate its amount or concentration in the original sample.

Summary: Gravimetric analysis involves preparing the sample, precipitating and isolating the target constituent, and accurately weighing the dried precipitate to determine the concentration of the constituent in the sample.

What is the advantage of the gravimetric method?

• Precise and accurate

• Requires expensive apparatus

• Provides room for instrumental error

• Fast and efficient

Answer explanation

The gravimetric method's main advantage is its high precision and accuracy in measuring the mass of a substance. This method is highly reliable because it directly measures the mass, minimizing errors associated with other methods. The results are consistent and reproducible, making it a preferred choice for quantitative analysis in various scientific fields.

What is the disadvantage of the gravimetric method?

• Simple and straightforward

• Low accuracy

• Time-consuming

• Does not require calibration

Answer explanation

The gravimetric method, which involves measuring the mass of a substance to determine its concentration or amount, can be disadvantageous due to being time-consuming. This is because it requires multiple steps, including the precise measurement of masses, filtration, drying, and sometimes heating, all of which take considerable time to complete.

What is the basis of gravimetric analysis?

• Measurement of temperature

• Measurement of density

• Measurement of volume

• Measurement of weight

Answer explanation

Gravimetric analysis is based on the measurement of weight. It involves determining the quantity of an analyte by isolating it in a pure, stable form and then measuring its mass. This method relies on the accurate weighing of the substance to quantify the amount of analyte in a sample.

Which type of gravimetric analysis involves isolating components by heating or chemically decomposing the sample?

• Thermogravimetric

• Volatilization Gravimetry

• Precipitation Gravimetry

• Electrogravimetry

Answer explanation

Volatilization gravimetry is a type of gravimetric analysis where components are isolated by heating or chemically decomposing the sample. This process involves the conversion of a sample component into a volatile form, which is then separated from the non-volatile residues. By measuring the mass of the volatile component lost during heating or decomposition, the amount of that component in the original sample can be determined.

What is the most commonly used method for isolating the desired constituent from a solution of a sample?

• Filtration

• Distillation

• Evaporation

• Precipitation

Answer explanation

The most commonly used method for isolating a desired constituent from a solution is precipitation.

Precipitation is a process where a substance is separated from a solution by forming a solid, known as a precipitate. This occurs when the concentration of the substance in the solution exceeds its solubility, causing it to form a solid phase that can be easily separated by filtration or centrifugation. Precipitation is widely used because it is often simple, cost-effective, and efficient for separating and purifying specific components from complex mixtures.