given the mass of a popcorn kernel. told the % water in kernel, given temperature of water vapor and pressure. find many mL of water vapor is there...i know you use PV=nRT but i cant find out what an example of this problem would look like
I would expect that you had mass of popcorn and % water, that will give you the mass of water when it pops.And if the temperature is up around 100 C, which I assume it will be to pop, then all of it will be in the vapor phase and you don't need PV = nRT
To solve this problem, we can use the ideal gas law equation PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
In this case, you are given the mass of the popcorn kernel, the percentage of water in the kernel, the temperature of the water vapor, and the pressure. Let's break down the steps to solve this problem:
1. Determine the number of moles of water:
First, we need to calculate the number of moles of water in the popcorn kernel. To do this, we will need the molecular weight of water, which is approximately 18 g/mol.
Number of moles of water = (mass of popcorn kernel in grams) x (% water in kernel / 100) / (molecular weight of water)
For example, if the mass of the popcorn kernel is 10 grams and the percentage of water in the kernel is 10%:
Number of moles of water = 10 g x (10% / 100) / 18 g/mol = 0.0556 mol
2. Convert the temperature to Kelvin:
You mentioned that you have the temperature of the water vapor. To use the ideal gas law, you need to convert the temperature to Kelvin. Kelvin is the absolute temperature scale, and it is obtained by adding 273.15 to the temperature in Celsius.
For example, if the temperature of the water vapor is 25 degrees Celsius:
Temperature in Kelvin = 25 + 273.15 = 298.15 K
3. Solve for volume:
Now that we have the number of moles of water (n), the temperature (T), and the pressure (P), we can solve for the volume (V) using the ideal gas law equation.
V = (n x R x T) / P
The ideal gas constant (R) is approximately 0.0821 L·atm/(mol·K).
For example, if the pressure is 1 atm:
V = (0.0556 mol x 0.0821 L·atm/(mol·K) x 298.15 K) / 1 atm = 1.38 L
4. Convert volume to mL:
Finally, if you want the volume in milliliters, you can convert it by multiplying the volume in liters by 1000.
For example,
Volume in mL = 1.38 L x 1000 mL/L = 1380 mL
Therefore, in this example, there would be approximately 1380 mL of water vapor present.