Hi! I need help with my Chem homework.
"When acetylene, C2H2, burns, how many liters of O2 at STp are used for every mole of acetylene burned?"
(Balanced equation: 2 C2H2 + 5 O2 --> 4 CO2 + 2 H2O)
To determine how many liters of O2 at STP (Standard Temperature and Pressure) are used for every mole of acetylene burned, we can examine the balanced chemical equation:
2 C2H2 + 5 O2 → 4 CO2 + 2 H2O
From the balanced equation, we see that 5 moles of O2 are required to burn 2 moles of acetylene.
Now, we need to convert moles of O2 to liters at STP. At STP, 1 mole of any gas occupies a volume of 22.4 liters. Therefore, we can set up a conversion factor:
5 moles O2 = 22.4 liters O2
So, for every mole of acetylene burned, 5 moles of O2 (or 22.4 liters at STP) are required.
To find out how many liters of O2 at STP (Standard Temperature and Pressure) are used for every mole of acetylene burned, we need to use the balanced chemical equation and the ideal gas law.
The balanced equation tells us that for every 2 moles of acetylene (C2H2) burned, we need 5 moles of O2. However, we want to find the volume of O2, not the number of moles.
To convert from moles to liters at STP, we need to use the ideal gas law equation PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the ideal gas constant, and T is temperature.
At STP, the temperature is 273.15 K and the pressure is 1 atm. The ideal gas constant, R, is 0.0821 L·atm/mol·K.
First, we need to convert the given number of moles of O2 to liters.
Using the balanced equation, we know that for every 5 moles of O2, we need 2 moles of acetylene burned.
So, if we have 5 moles of O2, we have 2 moles of acetylene burned.
Using the ideal gas law equation, we can rearrange it to solve for V (volume):
V = nRT / P
Plugging in the values, we get:
V = (2 mol) * (0.0821 L·atm/mol·K) * (273.15 K) / (1 atm)
Calculating this, we get:
V = 44.8 L
Therefore, when acetylene burns, 44.8 liters of O2 at STP are used for every mole of acetylene burned.