Answer to Question #160999 in General Chemistry for Arvin Shopon

Question

WORK 7. APPLICATION OF THE IDEAL GAS STATE EQUATION WORKING INSTRUCTIONS

OBJECTIVES OF THE WORK 

• Determine the cracking pressure of popcorn by applying the state equation of ideal gas.

• Determine the water content of popcorn as a percentage by mass.

• Consider the sources of error of the experimental method.

 

PERFORMANCE OF WORK

 

Materials and equipment required

- maize grains

- cooking oil

- conical flask (100 ml)

- measuring glass (10 ml)

- hot plate

- Analytical balance

Do this

1. Place cooking oil on the bottom of the conical flask so that the bottom of the bottle is covered. Weigh the total mass of the bottle and oil.

 

2. Weigh 15 corn kernels.

 

3. Add the weighed corn grains to the bottle and heat the bottle until all the grains are

cracked. Be careful not to burn the grains! Cool the bottle and reweigh it.

 

4. While waiting for the bottle to cool, take 15 grains of corn and determine their volume by adding 5.0 ml of water to a 10 ml beaker and adding the grains to the beaker.

 

PROCESSING, INTERPRETATION, AND CONCLUSIONS

1. Table all weighing results.

 

2. Calculate the mass of evaporated water and solve the mass percentage of water in the grains. Express the result to two significant figures.

 

3. Calculate the amount of evaporated water.

 

4. Solve the water vapor pressure inside the grains at the moment of cracking using the ideal gas space equation. Assume that the volume of water vapor is the same as the measured volume of the grains and that the grains crack at a temperature of 180 °C. Round the answer to the nearest two significant digits.

 

5. Consider which factors (mention two) contribute to the calculated pressure not being correct. Justify whether the calculated pressure is too low or too high due to the factors you mentioned.

Answer 1

If the kernel is heated to a high enough temperature, this water will transform into steam. ... As the popcorn is heated, the water turns into steam, which builds pressure inside the kernel. When the hull can no longer contain the pressure — POP! — the kernel explodes and a fluffy new piece of popcorn is born.