Question No.1. Student X decided to perform a science experiment, where she want

Question

Question No.1. Student X decided to perform a science experiment, where she wanted to determine the pressure within the classroom. She took a balloon and inflated it to 1.50L (at 19 degrees celsius), and then heated up the balloon to 22 degrees celsius. The balloon grew to a size of 1.9 L after heated. When released outside, the pressure in the balloon was 103 kPa. What was the original pressure of the balloon, when still inside? Show all work (Formal method).

Question No.2. Place one big marshmallow on the plate and put it in the microwave oven on (High), then allow it to run for about 45 seconds...What happened to the marshmallow as the time grew closer and closer to 45 seconds...explain your results

Explanation / Answer

First lets convert your figures to standard metric units - always do this first - celsius, Litres, etc. BAD BAD BAD (most of the time).

Metric Units:
Pressure = pascals, Pa
Temperature = kelvin, K
Volume = metres cubed, m^3

To get the temperature in kelvin (for any temperature) we simply add 273 degrees to the number in celsius - i.e. at 19 degree C (the initial temperature) this is 273 + 19 degree kelvin = 292 degrees kelvin.

If you do this for the final temperature (22 degrees C) you will get 295 degrees kelvin. Now you have finished converting temperature.

Pressure. This is easy. The units kPa mean kilo-pascals (kilo meaning 1000), therefore the pressure we have in the question (103 kPa) is just 103,000 Pa. Now you have finished converting pressure.

Volume. This is also relatively easy. 1000 L = 1 m^3, therefore if you divide your units of volume, which in this case is litres, by 1000 you will get your units in m^3. So the initial volume of the balloon is 1.5 L, this is actually 0.0015 m^3. And if you do the same calculation, the final volume of the balloon is 0.0019 m^3.

Once you have done this you can use the ideal gas law:

PV = nRT

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