Unit 4 AP Chemistry Gravimetric Analysis

What does the TARE button do?

• resets the reading to zero

• doubles the previous reading

• gives an average of the previous two readings

• makes the reading more accurate and precise

Weighing by difference is the same thing as weighing accurately approximately.

• TRUE

• FALSE

Weigh accurately and approximately 5 g to four significant figures. Check all the correct recorded readings.

• 5 g

• 5.000 g

• 5.011 g

• 5.014 g

• 5.00

Name this technique: Heating a substance, allowing it to cool in a desiccator, weighing it and repeating the steps until no further changes in mass observed.

• Weighing boat analysis

• Weighing by difference

• Weighing accurately and approximately

• Heating to constant mass

Why is a desiccator used in gravimetric analysis?

• to prevent reabsorption of water

• to heat up the sample

• to weigh the sample precisely and accurately

• to remove all moisture from a wet sample

Gravimetric analysis is used to determine the mass of an element or compound in a substance.

• TRUE

• FALSE

In gravimetric analysis, a substance is converted into another substance of known chemical composition, which can be readily isolated and purified. Check the possible ways of obtaining the new substance. (There are two).

• precipitation

• volatilisation

• oxidation

• reduction

• Cannibalization

In precipitation conversion, why is the filtrate tested?

• To check if reaction has gone to completion.

• To check for presence of water.

• To check for impurities.

• To check for presence of volatile substances.

In _________ conversion the substance is heated and any volatile products (often water) are evaporated. The substance is heated to constant mass and the final mass recorded.

• volatilisation

• precipitation

• volumetric

• extraction

• catholic

Tags

NGSS.HS-PS3-4